Pseudoephedrine hydrochloride

What it is

Pseudoephedrine hydrochloride is a salt of pseudoephedrine, a stereoisomer of ephedrine. It is an indirect-acting sympathomimetic: rather than stimulating adrenergic receptors itself, it makes nerve endings release noradrenaline, which constricts the blood vessels in the swollen nasal lining and so opens the airway. It is sold over the counter as 30, 60 and 120 mg tablets alone and inside dozens of antihistamine and analgesic combinations, and in the United States it sits behind the pharmacy counter because it can be converted into methamphetamine.

What the research says

It does open a blocked nose, and the effect is real but small. Objective measurements of nasal airway resistance improved against placebo after a single 60 mg dose, and in a paediatric trial it beat placebo over the first 8 hours on day 1 but only numerically on day 2. Cochrane's review of antihistamine-decongestant combinations for the common cold found a worthwhile-looking number needed to treat of about 4 for a global response, while concluding that the effect on individual symptoms is probably too small to be clinically relevant. Against that: a meta-analysis found it raises systolic blood pressure by about 1 mmHg and heart rate by about 3 beats a minute, it causes insomnia in around 6% against 1% on placebo, and there is a case literature of ischaemic colitis, stroke and the reversible brain syndromes PRES and RCVS that led European regulators to restrict it in 2024.

Evidence grade: Limited evidence.

How it works

Drug class: Indirect-acting sympathomimetic amine (oral nasal decongestant)

Pseudoephedrine does not act on adrenergic receptors directly. It enters sympathetic nerve endings and makes them release their stored noradrenaline, which then constricts blood vessels. In the nose this shrinks the engorged mucosa and lowers airway resistance; elsewhere in the body the same mechanism is what raises heart rate and blood pressure a little and can constrict vessels in the gut and brain. Animal work shows it also binds the noradrenaline transporter with affinity comparable to cocaine's, while having at least 200-fold lower affinity for dopamine and serotonin transporters. (Source 1)

What it is used for

• A 238-patient placebo-controlled trial using objective posterior rhinomanometry found a single 60 mg dose significantly lowered nasal airway resistance and subjective congestion on day 1; after three days of repeated dosing the objective measure still favoured pseudoephedrine but the subjective visual analogue scores no longer differed. The effect is genuine and modest. Evidence: limited. (Source 2)
• A manufacturer-supported multicentre randomised trial of 30 mg tablets found pseudoephedrine superior to placebo over the first 8 hours on day 1, with a least-squares mean difference of 1.2 on the congestion severity score (P = .029); day-2 secondary endpoints were only numerically favourable. Somnolence was commoner on drug. Single-ingredient 60 mg labels nonetheless say not for children under 12. Evidence: limited. (Source 3)
• In an 874-patient placebo-controlled trial of a loratadine-pseudoephedrine combination against each component alone, the combination beat placebo on composite symptom scores and beat loratadine alone on nasal stuffiness, confirming that the decongestant is what relieves blockage. Insomnia and nervousness were significantly commoner in the pseudoephedrine-containing arms. Evidence: established. (Source 4)
• Cochrane pooled six trials of antihistamine-decongestant combinations and found an odds ratio of treatment failure of 0.31 with a number needed to treat of about 4, moderate certainty, yet concluded the effect on individual symptoms is probably too small to be clinically relevant and that there is no evidence of effectiveness in young children. Evidence: disputed. (Source 5)
• This is not a therapeutic use. Monkey self-administration work shows pseudoephedrine functions as a weak positive reinforcer, 10- to 33-fold less potent than cocaine, suggesting relatively low abuse potential in itself. Its larger role is as a chemical precursor: controls on pseudoephedrine supply were followed by large, sustained falls in the estimated number of US methamphetamine users. Evidence: not-supported. (Source 6)

Interactions

• Monoamine oxidase inhibitors (label): This is the interaction both the prescription and the over-the-counter labels treat as absolute. MAO inhibitors increase the effect of indirect sympathomimetics like pseudoephedrine, and the combination can cause a hypertensive crisis. The restriction extends 14 days past stopping the MAO inhibitor. (Source 7)
• Antihypertensive medicines that act on sympathetic activity (label): Because pseudoephedrine releases noradrenaline, it can work against blood-pressure drugs that reduce sympathetic activity and blunt their effect. (Source 7)
• Other sympathomimetic amines (including other decongestants and stimulants) (label): Stacking pseudoephedrine with another sympathomimetic adds cardiovascular effects, which the label warns may be harmful. (Source 7)
• Alcohol and other central nervous system depressants (label): The prescription combination's label says alcohol and other CNS depressants add to the reduction in alertness and impairment of performance, and should be avoided. That warning attaches to the antihistamine in the product rather than to pseudoephedrine, which is stimulating rather than sedating. (Source 7)
• Caffeine, and bitter orange (p-synephrine) stimulant supplements (clinical trial): Caffeine on its own raised systolic blood pressure in a placebo-controlled crossover study, while p-synephrine from bitter orange did not, and adding p-synephrine to caffeine did not make the blood pressure or heart rate response worse. There is no equivalent controlled study of pseudoephedrine plus caffeine or plus bitter orange, so stacking pseudoephedrine with stimulant supplements remains theoretical rather than measured. (Source 8)
• Severe or uncontrolled high blood pressure, and severe kidney disease (conditions rather than drugs, but the key co-exposure) (label): European regulators made these absolute contraindications in 2024 because they are risk factors for the PRES and RCVS brain syndromes seen with pseudoephedrine. (Source 9)
• Thyroid disease, heart disease, high blood pressure, diabetes and prostatic enlargement (label): The over-the-counter label tells people with any of these to ask a doctor before use, because pseudoephedrine's sympathomimetic action can worsen each of them. (Source 10)

Stopping it

• There is no withdrawal syndrome or taper described for oral pseudoephedrine in the labels or the literature we searched. Stopping is framed in terms of symptoms and duration: the label says to stop and see a doctor if nervousness, dizziness or sleeplessness occur, or if symptoms do not improve within 7 days. (Source 10)
• Where harm has occurred, stopping is the treatment. In the ischaemic colitis series all four women recovered after stopping pseudoephedrine and none relapsed over 8 to 12 months of follow-up. (Source 11)
• European regulators instruct immediate stopping, not tapering, if symptoms of PRES or RCVS appear, and report that most cases resolved after the medicine was stopped. The wording quoted is from the section EMA addressed to patients; the parallel section for healthcare professionals says the same thing in clinician-directed words. (Source 12)

What goes wrong

A meta-analysis of 24 placebo-controlled trials found oral pseudoephedrine raises systolic blood pressure by about 1 mmHg and heart rate by about 3 beats per minute, with no effect on diastolic pressure. (Source 13)

• Meta-analysis, Moderate certainty.
• Size: 24 trials with extractable vital sign information, 45 treatment arms, 1285 patients.
• Who: adults given oral pseudoephedrine in randomised placebo-controlled trials, including a subgroup with controlled hypertension.
• How long: varied; shorter duration of use was associated with greater systolic rises.
• Result: Systolic BP +0.99 mmHg (95% CI 0.08 to 1.90); heart rate +2.83 beats/min (95% CI 2.0 to 3.6); diastolic BP +0.63 mmHg (95% CI -0.10 to 1.35), not significant. In people with controlled hypertension the systolic rise was 1.20 mmHg (95% CI 0.56 to 1.84). Higher doses and immediate-release preparations gave greater rises.
• Funding: not stated.

Limit of this finding: A 1 mmHg average rise is not clinically meaningful for most people; the numbers matter because they are small, which argues against the common blanket warning, while leaving open the question of rare susceptible individuals.

Pseudoephedrine caused a small but significant increase in SBP (0.99, mm Hg; 95% CI, 0.08 to 1.90) and HR (2.83 beats/min; 95% CI, 2.0 to 3.6), with no effect on DBP (0.63 mm Hg, 95% CI, -0.10 to 1.35). The effect in patients with controlled hypertension demonstrated an SBP increase of similar magnitude (1.20 mm Hg; 95% CI, 0.56 to 1.84 mm Hg).

In the pooled controlled trials on a prescription label, pseudoephedrine alone caused insomnia in 6% of recipients against 1% on placebo, nervousness in 4% against 1%, and dry mouth in 5% against 2%. (Source 14)

• Randomized trial, Moderate certainty.
• Size: 887 patients on pseudoephedrine and 1767 on placebo across 33 controlled and 15 uncontrolled US studies.
• Who: patients treated for allergic rhinitis, mostly for less than 90 days.
• How long: one day to one year, mostly under 90 days.
• Result: Insomnia 6% versus 1% placebo, nervousness 4% versus 1%, dry mouth 5% versus 2%, somnolence 8% versus 6%, dizziness 3% versus 2%; the label marks insomnia, nervousness, somnolence and dry mouth as statistically higher than placebo at p ≤ 0.05.
• Funding: industry (manufacturer's label)

Limit of this finding: The table's restored caption says the numbers are the percentage of patients reporting, not counts of patients: 'Headache 18' means 18 per cent. They are spontaneously reported events pooled across 33 controlled and 15 uncontrolled studies on the manufacturer's label, and only events above 1 per cent in the combination arm were tabulated, so this is not a complete adverse-effect profile.

TABLE 1 ADVERSE EVENTS REPORTED IN CLINICAL TRIALS* (PERCENT OF PATIENTS REPORTING)† Controlled Studies Placebo (N = 1767) Acrivastine (N = 1935) Pseudoephedrine (N = 887) Acrivastine plus Pseudoephedrine (N = 1650) *Includes all events regardless of casual relationship to treatment. †Includes all adverse events with a reported frequency of > 1% for the acrivastine plus pseudoephedrine treatment group. ‡SEMPREX-D demonstrates a statistically higher frequency of events than placebo, p ≤ 0.05. CNS Somnolence‡ 6 12 8 12 Headache 18 19 19 19 Dizziness 2 3 3 3 Nervousness‡ 1 2 4 3 Insomnia‡ 1 1 6 4 MISCELLANEOUS Nausea 2 3 3 2 Dry Mouth‡ 2 3 5 7

After reviewing all available data including post-marketing reports, the European Medicines Agency concluded in January 2024 that pseudoephedrine is associated with the rare brain syndromes PRES and RCVS, and restricted its use. (Source 9)

• Official position, Certainty not rated.
• Size: not stated; the agency describes few reported cases.
• Who: users of pseudoephedrine-containing medicines across the European Union.
• How long: procedure started 9 February 2023, PRAC recommendation 30 November 2023, CHMP opinion 25 January 2024, European Commission decisions March 2024.
• Result: No fatal cases of PRES or RCVS were reported and most resolved after the medicine was stopped. The medicines must not be used in severe or uncontrolled hypertension or severe acute or chronic kidney disease or renal failure.
• Funding: not applicable (regulatory review)

Limit of this finding: This is a regulator's position with a date, derived largely from spontaneous reports, not a controlled study, and the agency itself notes the cases were few. The wording quoted here is from the page's section written for healthcare professionals, which calls PRES and RCVS 'serious conditions'; the section EMA wrote for patients calls them 'rare conditions'. Both are the agency's own words about the same two syndromes: serious if they happen, rarely reported.

An EMA review has found that pseudoephedrine-containing medicines are associated with risks of posterior reversible encephalopathy syndrome (PRES) and reversible cerebral vasoconstriction syndrome (RCVS), serious conditions affecting the cerebral blood vessels. This follows an evaluation of all available data including few reported cases of these conditions. There were no fatal cases of PRES or RCVS reported, and most of the cases resolved following discontinuation of the medicine and appropriate treatment.

A man with no known systemic disease had a generalised tonic-clonic seizure after two doses of a paracetamol-pseudoephedrine product, with MRI changes diagnostic of posterior reversible encephalopathy syndrome. (Source 15)

• Case report, Very low certainty.
• Size: 1 patient.
• Who: a 56-year-old man with no known systemic disease taking oral paracetamol plus pseudoephedrine hydrochloride for cold symptoms.
• How long: seizure after the second dose.
• Result: bilateral cortical and subcortical hyperintensities in the posterior hemispheres and cerebellar hemispheres on FLAIR MRI, consistent with PRES.
• Funding: none declared.

Limit of this finding: A single case. The report also states that the patient was diagnosed with hypertension and diabetes during follow-up, so he was not in fact free of PRES risk factors, which weakens the attribution. The report is internally inconsistent on this point: it introduces the patient as having no known systemic disease and then records hypertension diagnosed during follow-up.

A 56-year-old man with no known systemic disease with generalized tonic clonic seizure was evaluated. He had oral paracetamol + pseudoephedrine HCl for runny nose, sore throat, and headache. After the second dosage, he had a seizure while sleeping. In flair sequence of magnetic resonance imaging, bilateral cortical and subcortical hyperintensities were observed in the posterior parts of the hemispheres and the cerebellar hemispheres, which demonstrated PRES.

Four women developed ischaemic colitis in the watershed area of the splenic flexure while taking pseudoephedrine, and all recovered after stopping it with no relapse over 8 to 12 months. (Source 16)

• Case series, Very low certainty.
• Size: 4 women aged 37 to 50.
• Who: women presenting with sudden colicky abdominal pain followed by rectal bleeding; two had no significant past medical history.
• How long: daily use for about a week in three patients, chronic use for 6 months in the fourth; follow-up 8 to 12 months.
• Result: colonoscopy showed colitis primarily affecting the splenic flexure watershed area in all four, with biopsies consistent with ischaemic injury; all responded to stopping pseudoephedrine and none relapsed.
• Funding: not stated.

Limit of this finding: Four cases cannot give a rate, and the authors' proposed mechanism involving oestrogen in perimenopausal women is speculation stated as a possibility.

We reviewed the cases of four women (ages, 37-50 yr) who presented with the sudden onset of colicky abdominal pain followed by hematochezia. Three patients had used medicine containing pseudoephedrine daily for approximately 1 wk before admission. The fourth patient had used pseudoephedrine chronically for 6 months. Two patients had no significant past medical history. One woman had presented 6 months earlier with ischemic colitis while taking both pseudoephedrine and hormone replacement therapy. This time she presented with ischemic colitis while not taking hormone replacement therapy, but still taking decongestants. Another woman had a history of ulcerative colitis, which had been quiescent for 10 yr. One patient had been a smoker; however, like the other patients she had no evidence of systemic vascular disease. On colonoscopy, all four patients had colitis, primarily affecting the splenic flexure in the anatomical watershed area. Other causes of segmental colitis, including infectious colitides, pseudomembranous colitis, and Crohn's disease, were not evident. Colonoscopic biopsies were consistent with ischemic injury.

A further published case describes pseudoephedrine-induced ischaemic colitis in a healthy woman with no risk factors, and reviews the earlier cases. (Source 17)

• Case report, Very low certainty.
• Size: 1 patient.
• Who: a healthy woman with no risk factors for ischaemic colitis.
• How long: not stated in the abstract.
• Result: no rate; the case adds to a number of previously described cases with pseudoephedrine as the culprit agent.
• Funding: not stated.

Limit of this finding: A case report with a narrative literature review; it cannot give an incidence.

Ischemic colitis due to medications is common, and a number of cases have been described with pseudoephedrine as the culprit agent. We present here an interesting case of a healthy female with no risk factors who developed pseudoephedrine induced ischemic colitis.

In men without urinary symptoms, one week of pseudoephedrine measurably worsened prostate symptom scores in those aged 50 and over, but not in younger men. (Source 18)

• Cohort study, Low certainty.
• Size: 131 men, mean age 42.0 ± 14.3 years.
• Who: men with nasal congestion requiring pseudoephedrine who denied any urinary problem.
• How long: 1 week.
• Result: Across the whole group the International Prostate Symptom Score rose only slightly (total from 6.49 to 6.77). In men aged 50 and over the total rose from 9.95 to 11.45, the voiding subscore from 5.38 to 6.07 and the storage subscore from 4.57 to 5.38, all significant; in men under 50 no score differed significantly.
• Funding: not stated.

Limit of this finding: A single-arm before-and-after study with no control group, so some of the change could be regression or illness effects rather than the drug.

In patients aged ≥50 years, the IPSS-T, IPSS-V, and IPSS-S scores significantly increased after the pseudoephedrine treatment (IPSS-T increased from 9.95 to 11.45, IPSS-V from 5.38 to 6.07, and IPSS-S 4.57 to 5.38), whereas the quality of life due to urinary symptom score nonsignificantly decreased from 2.71 to 2.48 (P=0.057). In patients aged <50 years, all scores did not significantly differ.

Pseudoephedrine functions as a weak positive reinforcer in monkeys, 10- to 33-fold less potent than cocaine, which the authors read as relatively low abuse potential. (Source 6)

• Animal study, Very low certainty.
• Size: 4 rhesus monkeys for self-administration; 3 for the levorotatory isomer.
• Who: rhesus monkeys, plus in-vitro binding in monkey brain tissue and human dopamine transporter cells.
• How long: not stated.
• Result: Both isomers functioned as positive reinforcers but were 10- to 33-fold less potent than cocaine; affinity for dopamine and serotonin transporters was at least 200-fold lower than cocaine's, while affinity for noradrenaline transporters was comparable.
• Funding: not stated.

Limit of this finding: Monkeys, not people. This cannot be stated as a human finding, and the authors' own reading is that the abuse potential is relatively low. PubMed also renders the paper's stereochemistry in plain ASCII as '+-pseudoephedrine', which reads as 'plus or minus', i.e. the racemic mixture. The paper means the (+) isomer, and the whole point of it is that the two isomers differ.

When made available to rhesus monkeys (n = 4) for self-administration, +-pseudoephedrine functioned as a positive reinforcer in all monkeys, as did (-)-pseudoephedrine in two of three monkeys. Pseudoephedrine isomers were 10- to 33-fold less potent than cocaine.

The over-the-counter label records pseudoephedrine's own position on who should not take it and when to stop, including nervousness, dizziness and sleeplessness as reasons to stop. (Source 10)

• Official position, Certainty not rated.
• Size: not applicable.
• Who: adults and children 12 and over buying the product over the counter.
• How long: not applicable; the label caps use at 7 days before seeing a doctor.
• Result: no rates given on the label.
• Funding: not applicable (manufacturer label)

Ask a doctor before use if you have thyroid disease heart disease high blood pressure diabetes trouble urinating due to an enlarged prostate gland When using this product do not exceed recommended dose. Stop use and ask a doctor if nervousness, dizziness, or sleeplessness occur symptoms do not improve within 7 days or occur with fever

What the evidence supports

In children aged 6 to 11, pseudoephedrine 30 mg beat placebo for nasal congestion over the first 8 hours of day 1, with a difference of 1.2 points on the congestion severity score, but day-2 endpoints were only numerically favourable. (Source 3)

• Randomized trial, Low certainty.
• Size: not stated in the abstract; the adverse-event denominators imply roughly 32 children per arm for sleepiness ratings.
• Who: children aged 6 to 11 years with nasal congestion due to the common cold, multicentre.
• How long: dosing as needed for up to 7 days, with the primary endpoint over 1 to 8 hours on day 1.
• Result: Least squares mean difference between treatment groups 1.2 (P = .029) for the weighted sum of change in instantaneous nasal congestion severity. Somnolence 71.9% on pseudoephedrine versus 63.9% on placebo; insomnia 34.4% versus 38.9%; nervousness 20.0% versus 23.6%.
• Funding: industry-funded: the authors were paid consultants of the Consumer Healthcare Products Association, an employee of the contract research organisation, and an employee of Perrigo Company, which paid for the study on behalf of CHPA.

Limit of this finding: A single trial, funded by the trade association whose members sell the product, with a benefit confined to day 1. The very high somnolence rates in both arms suggest the rating instrument captured ordinary illness, not drug effect. The 71.9 per cent somnolence figure must never be shown on its own: placebo was 63.9 per cent, and insomnia (34.4 against 38.9 per cent) and nervousness (20.0 against 23.6 per cent) were both commoner on placebo than on pseudoephedrine. These were solicited ratings in children with a cold, so most of what they captured was the illness.

Pseudoephedrine was superior to placebo in reducing instantaneous nasal congestion severity in pediatric children over the first 8 hours after dosing on day 1 (least squares mean difference between treatment groups was 1.2; P = .029). Overall, secondary end points associated with nasal congestion were supportive on day 1, whereas secondary end points on day 2 were only numerically favorable.

In an 874-patient trial, a loratadine-pseudoephedrine combination beat placebo in seasonal allergic rhinitis and beat loratadine alone for nasal stuffiness, while insomnia and nervousness were significantly commoner in the pseudoephedrine arms. (Source 4)

• Randomized trial, Moderate certainty.
• Size: 874 patients.
• Who: patients with moderate to severe seasonal allergic rhinitis, multicentre.
• How long: 2 weeks.
• Result: Composite total, total nasal and total nonnasal symptom scores all reduced significantly versus placebo (p < 0.01). The combination was superior to pseudoephedrine alone for nonnasal symptoms (p < 0.01) and superior to loratadine alone for nasal stuffiness at endpoint (p < 0.01). 58% of combination patients were rated good or excellent by physicians. Insomnia and nervousness were significantly commoner with the combination or pseudoephedrine alone than with loratadine or placebo (p ≤ 0.04).
• Funding: industry-funded; the product is identified by its sponsor development code SCH 434 and the author list includes sponsor-affiliated investigators.

SCH 434 QD was consistently superior to placebo in controlling the symptoms of seasonal allergic rhinitis. Composite symptom scores (total, total nasal, and total nonnasal) were reduced significantly in patients treated with SCH 434 QD as compared with placebo (p < 0.01). When compared with its individual components, reductions in mean symptom scores were consistently greater, numerically, in patients treated with SCH 434 QD than in patients who were treated with either loratadine or pseudoephedrine alone. SCH 434 QD was superior to pseudoephedrine in reducing nonnasal symptoms at all time points (p < 0.01), and superior to loratadine in relieving nasal stuffiness at end point (p < 0.01). In the physicians' evaluation of therapeutic response, the SCH 434 QD group had the greatest number of patients with a good or excellent response at end point (58%). All treatments were generally well tolerated with no serious or unusual adverse events. Insomnia and nervousness, adverse events commonly associated with pseudoephedrine, were noted in a significantly greater number of patients treated with SCH 434 QD or pseudoephedrine (p < or = 0.04) as compared with those treated with loratadine or placebo.

What the evidence does not support

The same Cochrane review's overall conclusion is that the benefit is small, must be weighed against adverse effects, and is unproven in young children. (Source 19)

• Systematic review, Low certainty.
• Size: 30 studies, 6304 participants.
• Who: children and adults with the common cold.
• How long: 3 to 10 days.
• Result: no clinically relevant effect on individual symptoms; no evidence of effectiveness in young children.
• Funding: independent.

Limit of this finding: The review's conclusion pulls in two directions in its own words: it says the data are scarce and the effect on individual symptoms is probably too small to be clinically relevant, and then that the combinations have 'some general benefit in adults and older children'. Neither sentence should be quoted without the other. Its closing remark about the US FDA concerns phenylpropanolamine in 2005 and is a historical note inside the review, not a current regulatory position.

Based on these scarce data, the effect on individual symptoms is probably too small to be clinically relevant. The current evidence suggests that antihistamine-analgesic-decongestant combinations have some general benefit in adults and older children. These benefits must be weighed against the risk of adverse effects. There is no evidence of effectiveness in young children.

A journal review of common cold treatment states that current products may reduce the severity of some but not all symptoms and usually do not shorten the episode, and that phenylephrine's ineffectiveness means it will have to leave the monograph. (Source 20)

• Expert review, not systematic, Low certainty.
• Size: not applicable.
• Who: people with the common cold.
• How long: not applicable.
• Result: no effect sizes given; the review's position is that existing products do not shorten a cold.
• Funding: both authors declared travel support from Sen-Jam Pharmaceutical and the senior author declared consultancy for several companies including Red Bull and Sen-Jam Pharmaceutical.

Limit of this finding: A narrative review with declared commercial interests in common cold product development, so its framing of an unmet need should be read with that in mind.

The current products marketed for treating the common cold may reduce the severity of some (but not all) common cold symptoms, but they usually do not shorten the common cold episode.

Where the evidence is mixed

In a placebo-controlled trial using objective rhinomanometry, a single 60 mg dose of pseudoephedrine significantly lowered nasal airway resistance, but by day 3 the subjective congestion scores no longer differed from placebo. (Source 2)

• Randomized trial, Moderate certainty.
• Size: 238 patients.
• Who: patients with nasal congestion from acute upper respiratory tract infection, mean age 20 years, at a single centre.
• How long: 3 study days.
• Result: Day 1 nasal airway resistance area under the curve 0-3 h p = 0.006 and 0-4 h p = 0.001 in favour of pseudoephedrine; day 3 NAR AUC p < 0.001; day 1 subjective visual analogue scale AUC 0-3 h p = 0.029 and 0-4 h p = 0.021, but on day 3 the subjective differences were not significant. Heart rate averaged 2 to 4 beats per minute higher than placebo.
• Funding: not stated; two authors were affiliated with the product sponsor in the published author list.

Limit of this finding: The trial reports p-values rather than between-group effect sizes for the airway resistance outcome, so the size of the benefit a person would feel cannot be read off it.

After a single dose on day 1 the pseudoephedrine group had a statistically significant lower area under the NAR curve than placebo (p = 0.006) for the primary efficacy variable area under the NAR curve from 0-3 hours (NAR AUC 0-3h), and similarly for the secondary efficacy variable NAR AUC 0-4h (p = 0.001). On day three after multiple doses, the pseudoephedrine group had a statistically significant lower NAR AUC 0-3h and AUC 0-4h than placebo (p < 0.001), On day 1, the pseudoephedrine group had significantly lower subjective scores for congestion than placebo visual analog scale (VAS) AUC 0-3h (p = 0.029) and similarly for VAS AUC 0-4h (p = 0.021). On day 3, the differences in subjective scores were not significantly different.

The trial's own conclusion notes that multiple-dose efficacy was supported by the objective measure but not by the subjective day-3 scores. (Source 21)

• Randomized trial, Moderate certainty.
• Size: 238 patients.
• Who: patients with upper respiratory tract infection and nasal congestion.
• How long: 3 days.
• Result: single-dose superiority on both objective and subjective measures; multiple-dose support from objective measures and from the three-day summary score, but not from the day-3 visual analogue scores.
• Funding: not stated.

Support for the decongestant efficacy of multiple doses of pseudoephedrine is provided by objective measures on day 3 and subjective measures made over three days, but not by the VAS scores on day 3.

Cochrane found antihistamine-decongestant combinations gave a global benefit over control with a number needed to treat of about 4, while judging the effect on individual symptoms probably too small to be clinically relevant. (Source 5)

• Systematic review, Moderate certainty.
• Size: 14 trials of antihistamine-decongestant with 1298 participants; 565 participants in the pooled global-effectiveness analysis.
• Who: children and adults with the common cold.
• How long: final evaluation at 3 to 10 days.
• Result: Odds ratio of treatment failure 0.31 (95% CI 0.20 to 0.48), moderate certainty; number needed to treat for an additional beneficial outcome 3.9 (95% CI 3.03 to 5.2). On the final evaluation day 55% of the placebo group had a favourable response compared with 70% on active treatment, an absolute difference of 15 percentage points.
• Funding: independent (review authors declared no conflict of interest)

Limit of this finding: The review's own arithmetic does not hold in two places and we have kept its wording rather than correct it. It prints the control-arm adverse-effect rate as '100/423 (13%)' when 100 of 423 is 23.6 per cent, so the percentage understates the fraction printed beside it. Its two numbers needed to treat also do not follow from its own response rates and read as though they had been swapped: 70 against 55 per cent is a 15-point difference, which gives about 7, not the 3.9 printed, while 70 against 43 per cent gives about 4, not the 6.67 printed. Read the fractions and the percentage-point differences, not the derived figures.

The odds ratio (OR) of treatment failure was 0.31 (95% confidence interval (CI) 0.20 to 0.48; moderate certainty evidence); number needed to treat for an additional beneficial outcome (NNTB) 3.9 (95% CI 3.03 to 5.2). On the final evaluation day (follow-up: 3 to 10 days), 55% of participants in the placebo group had a favourable response compared to 70% on active treatment.

In 2024 the US FDA proposed removing oral phenylephrine from the over-the-counter monograph because it is not effective, which leaves pseudoephedrine as the only oral decongestant with monograph standing. (Source 22)

• Official position, Certainty not rated.
• Size: not applicable.
• Who: US over-the-counter nasal decongestant products.
• How long: proposed order published 8 November 2024, 89 FR 88787.
• Result: the proposed order would remove orally administered phenylephrine hydrochloride and phenylephrine bitartrate as nasal decongestant active ingredients.
• Funding: not applicable (regulatory position)

Limit of this finding: This is a dated proposal about a different drug. It raises, rather than settles, the question of how robust the evidence base for the whole oral decongestant class is, since pseudoephedrine's own trials are mostly small, short and sponsor-run.

This proposed order, if finalized, will amend Final Administrative Order OTC000026, to remove orally administered phenylephrine hydrochloride and phenylephrine bitartrate in an effervescent dosage as nasal decongestant active ingredients because they are not effective.

An independent systematic review of four randomised trials found oral phenylephrine no more effective than placebo for nasal congestion in adults, the comparison against which pseudoephedrine's modest effect should be read. (Source 23)

• Systematic review, Low certainty.
• Size: four articles meeting inclusion criteria.
• Who: adults with nasal congestion in trials published in English between 1998 and 2023.
• How long: varied.
• Result: The findings consistently indicated phenylephrine was not more effective than placebo; safety assessments showed no life-threatening adverse events, with headaches and mild discomfort the common side effects.
• Funding: independent (authors declared no competing interests)

Limit of this finding: Only four trials, and the review is about phenylephrine, not pseudoephedrine. It is included here because it is the evidence behind the regulatory position that reframed the oral decongestant class.

We identified four articles that met the criteria. These studies exhibited varied designs and populations. The findings consistently indicated that phenylephrine was not more effective than a placebo in relieving nasal congestion.

Controls on pseudoephedrine supply were followed by large and sustained falls in the estimated number of US methamphetamine users. (Source 24)

• Survey study, Low certainty.
• Size: National Survey on Drug Use and Health, n = 723,283 respondents, 52 quarterly time points.
• Who: the US civilian non-institutionalised population, 2002 to 2014.
• How long: 2002 to 2014, with the intervention in March 2007.
• Result: Past-year methamphetamine user numbers fell by 494,440 (-35%; P < 0.01; 95% CI -771,897 to -216,982) and past-month by 277,380 (-45%; P < 0.05; CI -554,073 to -686) from the time a Mexican chemical company accused of illicitly importing pseudoephedrine was closed. Heroin and marijuana comparison series changed little.
• Funding: not stated.

Limit of this finding: An interrupted time-series on survey estimates. It shows association with a policy date, not causation, and it is about diversion of the chemical rather than about medical use.

Downward shifts in methamphetamine users started at the time of the chemical company closure. Past-year and past-month methamphetamine series levels decreased by 494 440 (-35%) [P < 0.01; 95% confidence interval (CI) = -771 897, -216 982] and 277 380 (-45%) (P < 0.05; CI = -554 073, -686), respectively-partial recovery possibly occurred in 2013.

Where the research disagrees

Whether oral pseudoephedrine produces a clinically meaningful improvement in cold symptoms

• De Sutter, Eriksson and van Driel, Cochrane review 2022, systematic review of 30 trials in 6304 participants with GRADE certainty ratings: Based on these scarce data, the effect on individual symptoms is probably too small to be clinically relevant. (Source 19)
• Eccles and colleagues, placebo-controlled rhinomanometry trial, single-centre randomised placebo-controlled trial with objective nasal airway resistance measurement: The results from the laboratory study on day 1 demonstrate by both objective and subjective measures of nasal congestion that a single dose of 60 mg pseudoephedrine is superior to placebo treatment. (Source 21)

Whether pseudoephedrine's cardiovascular effect is large enough to matter

• Salerno, Jackson and Berbano, meta-analysis of 24 randomised trials, meta-analysis of 45 treatment arms in 1285 adults: Pseudoephedrine caused a small but significant increase in SBP (0.99, mm Hg; 95% CI, 0.08 to 1.90) and HR (2.83 beats/min; 95% CI, 2.0 to 3.6), with no effect on DBP (Source 13)
• The over-the-counter label, effective September 2026, regulatory position under the US over-the-counter monograph: Ask a doctor before use if you have thyroid disease heart disease high blood pressure diabetes (Source 10)

How much

• Reference intake: There is no reference intake for a medicine. The over-the-counter label records a position of one 60 mg tablet every 4 to 6 hours for adults and children 12 and over, and says children under 12 should not use it. (Source 25)
• Upper limit: The same over-the-counter label's ceiling is 4 tablets in 24 hours, which is 240 mg of pseudoephedrine hydrochloride a day. That is the labelled maximum under the US over-the-counter monograph, not a toxicological upper limit derived from study of pseudoephedrine, and no body we could reach has set an acceptable daily intake for it. (Source 25)
• Studied: The rhinomanometry trial gave a single 60 mg dose on day 1 and multiple doses to day 3 in 238 patients with a cold. (Source 2)
• Studied: The paediatric trial gave pseudoephedrine hydrochloride 30 mg tablets to children aged 6 to 11, as needed for up to 7 days. (Source 3)
• Studied: The allergic rhinitis trial gave 120 mg of pseudoephedrine sulfate every 12 hours as the comparator arm, and 240 mg in an extended-release core once daily in the combination arm. (Source 4)
• Studied: The meta-analysis of blood pressure effects pooled 45 treatment arms in 1285 adults, and found higher doses and immediate-release preparations gave greater blood pressure rises. (Source 13)

A common belief, and what the research shows

The belief: Pseudoephedrine is dangerous for anyone with high blood pressure because it sends blood pressure up sharply.

What the research shows: The meta-analytic numbers are small: systolic blood pressure rose on average 0.99 mmHg and heart rate 2.83 beats per minute across 24 trials, and in people whose hypertension was already controlled the systolic rise was 1.20 mmHg. That is not a sharp rise. The real signals sit elsewhere and are rarer: European regulators concluded in January 2024 that pseudoephedrine is associated with PRES and RCVS and made severe or uncontrolled hypertension and severe kidney disease absolute contraindications, and there is a case literature of ischaemic colitis and stroke. So the caution is justified for uncontrolled hypertension specifically, not by an average pressure rise of about 1 mmHg.

Questions and answers

What is it?

Pseudoephedrine hydrochloride is a manufactured medicine, a salt of pseudoephedrine, which is a stereoisomer of ephedrine. It is an oral nasal decongestant, sold as 30, 60 and 120 mg tablets on their own and inside many antihistamine and painkiller combinations. In the United States it is kept behind the pharmacy counter because it can be converted into methamphetamine. (Source 25)

What does it do in the body?

It is an indirect sympathomimetic: it makes sympathetic nerve endings release their stored noradrenaline, which constricts blood vessels. In the nose that shrinks the swollen lining and lowers airway resistance, which is why a blocked nose opens. The same mechanism elsewhere is why it nudges up heart rate and blood pressure, can keep people awake, and can constrict vessels in the gut and brain. (Source 1)

Is it good or bad for you?

Useful in small amounts for a short time, and risky in a few specific situations. It genuinely reduces nasal airway resistance, with a modest and short-lived symptomatic benefit. The common unwanted effects are insomnia in about 6% against 1% on placebo, nervousness, and roughly 1 mmHg more systolic pressure and 3 more heartbeats a minute. The serious harms are rare but real: ischaemic colitis, stroke, and the PRES and RCVS brain syndromes, which led European regulators to forbid it outright in severe or uncontrolled hypertension and severe kidney disease. (Source 12)

How do you get more of it?

This question does not apply as it would to a nutrient. Pseudoephedrine is not made by the body and is not needed by it, so there is no reason to seek more. Where it is obtained at all, it is from a pharmacy, and the labelled position is one 60 mg tablet every 4 to 6 hours with no more than 4 tablets in 24 hours for adults and children 12 and over. We record that as a label position, not as advice. (Source 25)

If it is harmful, what reduces it?

Pseudoephedrine is cleared mainly by the kidneys, so it leaves the body on its own within hours and stopping the tablets is what reduces it; people with impaired kidney function accumulate it. There is no antidote. In overdose the recorded picture is sympathomimetic excess, with restlessness, tremor, insomnia, hallucinations, convulsions and, at the extreme, arrhythmias and cardiovascular collapse, managed supportively. (Source 26)

Why might someone be low in it or missing it?

Having none is the normal state. What limits access or use is worth knowing: in the United States it sits behind the pharmacy counter under precursor controls; European regulators now forbid it in severe or uncontrolled hypertension and in severe acute or chronic kidney disease; the over-the-counter label tells people with thyroid disease, heart disease, high blood pressure, diabetes or prostate enlargement to ask a doctor first; and anyone on a monoamine oxidase inhibitor must not take it. (Source 10)

Which whole foods contain it or feed it?

No food contains pseudoephedrine. It occurs naturally in Ephedra species, from which ephedrine-type alkaloids are extracted, but it is not a dietary constituent and pharmaceutical supply is synthetic or extracted for manufacture. Foods and drinks matter in the other direction: caffeine-containing drinks and stimulant supplements such as bitter orange add to the stimulant load, although in a controlled study caffeine alone raised systolic pressure while bitter orange did not. (Source 8)

What happens if you do not have it?

Nothing happens physiologically from never taking it. What you forgo is a modest, short-lived reduction in nasal blockage. In Cochrane's pooled analysis of antihistamine-decongestant combinations, 55% of people on placebo had a favourable response by the final evaluation day against 70% on active treatment, so most people improve anyway and about 1 in 4 of those treated gets a response they would not otherwise have had. Colds resolve without it. (Source 5)

How can you test for it?

There is no test of pseudoephedrine status in healthy people and no reason to measure it in ordinary care. Plasma concentrations can be measured: the prescription label reports a maximum plasma concentration of 1308 ng/mL after a 60 mg dose, from pharmacokinetic screening in clinical trials. Urine testing for pseudoephedrine is used in sport doping control and in forensic toxicology. What is clinically useful instead is monitoring the effects, such as blood pressure, rather than the drug level. (Source 26)

We searched: Europe PMC searches for pseudoephedrine with pharmacokinetics, urine, doping, WADA, threshold and excretion terms; the retrievable studies measured plasma or urine levels for research or doping purposes, not as a clinical test of a patient's status.

References

1. DailyMed, US National Library of Medicine (FDA label). SEMPREX-D (acrivastine and pseudoephedrine hydrochloride) US prescribing information - CLINICAL PHARMACOLOGY. 2008. Read the source
2. American journal of rhinology. Efficacy and safety of single and multiple doses of pseudoephedrine in the treatment of nasal congestion associated with common cold - Results section of the abstract. 2005. PMID 15794071. Read the source
3. Journal of clinical pharmacology. A Multicenter, Randomized, Placebo-Controlled Study of Pseudoephedrine for the Temporary Relief of Nasal Congestion in Children With the Common Cold. 2019. PMID 31274197, DOI 10.1002/jcph.1472. Read the source
4. The Journal of allergy and clinical immunology. Comparative efficacy and safety of a once-daily loratadine-pseudoephedrine combination versus its components alone and placebo in the management of seasonal allergic rhinitis - Results section of the abstract. 1995. PMID 7636050, DOI 10.1016/s0091-6749(95)70001-3. Read the source
5. The Cochrane database of systematic reviews. Oral antihistamine-decongestant-analgesic combinations for the common cold - Main results section of the abstract. 2022. PMID 35060618, DOI 10.1002/14651858.CD004976.pub4. Read the source
6. European journal of pharmacology. Reinforcing effect of pseudoephedrine isomers and the mechanism of action. 2004. PMID 15189772, DOI 10.1016/j.ejphar.2004.04.030. Read the source
7. DailyMed, US National Library of Medicine (FDA label). SEMPREX-D (acrivastine and pseudoephedrine hydrochloride) US prescribing information - Drug Interactions. 2008. Read the source
8. Phytotherapy research : PTR. Acute cardiovascular effects of bitter orange extract (p-synephrine) consumed alone and in combination with caffeine in human subjects: A placebo-controlled, double-blind study. 2018. PMID 29047215, DOI 10.1002/ptr.5953. Read the source
9. European Medicines Agency. Pseudoephedrine-containing medicinal products - referral: outcome of the EU review - Information for healthcare professionals section. 2024. Read the source
10. DailyMed, US National Library of Medicine (FDA OTC monograph label). Pseudoephedrine hydrochloride 60 mg tablet (SudoGest) OTC Drug Facts label - Warnings section in full (Do not use, Ask a doctor before use if you have, When using this product, Stop use and ask a doctor if, pregnancy, keep out of reach of children, overdose). 2026. Read the source
11. The American journal of gastroenterology. Ischemic colitis associated with pseudoephedrine: four cases - Results section of the abstract. 1999. PMID 10484004, DOI 10.1111/j.1572-0241.1999.01369.x. Read the source
12. European Medicines Agency. Pseudoephedrine-containing medicinal products - referral: outcome of the EU review - Information for patients section. 2024. Read the source
13. Archives of internal medicine. Effect of oral pseudoephedrine on blood pressure and heart rate: a meta-analysis. 2005. PMID 16087815, DOI 10.1001/archinte.165.15.1686. Read the source
14. DailyMed, US National Library of Medicine (FDA label). SEMPREX-D (acrivastine and pseudoephedrine hydrochloride) US prescribing information - ADVERSE EXPERIENCES. 2008. Read the source
15. Clinical neuropharmacology. Posterior Reversible Encephalopathy Syndrome Occurred During the Use of Pseudoephedrine: A Case Report - Case presentation section of the abstract. 2022. PMID 36066857, DOI 10.1097/WNF.0000000000000520. Read the source
16. The American journal of gastroenterology. Ischemic colitis associated with pseudoephedrine: four cases - Methods section of the abstract. 1999. PMID 10484004, DOI 10.1111/j.1572-0241.1999.01369.x. Read the source
17. Case reports in gastrointestinal medicine. Pseudoephedrine Induced Ischemic Colitis: A Case Report and Review of Literature. 2018. PMID 30050703, DOI 10.1155/2018/8761314. Read the source
18. Drug design, development and therapy. Voiding dysfunction in patients with nasal congestion treated with pseudoephedrine: a prospective study - Results section of the abstract. 2016. PMID 27486310, DOI 10.2147/DDDT.S108819. Read the source
19. The Cochrane database of systematic reviews. Oral antihistamine-decongestant-analgesic combinations for the common cold - Authors' conclusions section of the abstract. 2022. PMID 35060618, DOI 10.1002/14651858.CD004976.pub4. Read the source
20. The journal of allergy and clinical immunology. Global. The common cold: The need for an effective treatment amid the FDA discussion on oral phenylephrine. 2024. PMID 39253103, DOI 10.1016/j.jacig.2024.100318. Read the source
21. American journal of rhinology. Efficacy and safety of single and multiple doses of pseudoephedrine in the treatment of nasal congestion associated with common cold - Conclusion section of the abstract. 2005. PMID 15794071. Read the source
22. Federal Register (US Food and Drug Administration). Amending Over-the-Counter Monograph M012: Cold, Cough, Allergy, Bronchodilator, and Antiasthmatic Drug Products for Over-the-Counter Human Use (proposed order OTC000036) - abstract. 2024. Read the source
23. Cureus. The Use and Efficacy of Oral Phenylephrine Versus Placebo Treating Nasal Congestion Over the Years on Adults: A Systematic Review. 2023. PMID 38125218, DOI 10.7759/cureus.49074. Read the source
24. Addiction (Abingdon, England). Essential/precursor chemicals and drug consumption: impacts of US sodium permanganate and Mexico pseudoephedrine controls on the numbers of US cocaine and methamphetamine users - Findings section of the abstract. 2016. PMID 27529812, DOI 10.1111/add.13480. Read the source
25. DailyMed, US National Library of Medicine (FDA OTC monograph label). Pseudoephedrine hydrochloride 60 mg tablet (SudoGest) OTC Drug Facts label - Active ingredient, Purpose, Uses and Directions sections, in the label's own order. 2026. Read the source
26. DailyMed, US National Library of Medicine (FDA label). SEMPREX-D (acrivastine and pseudoephedrine hydrochloride) US prescribing information - OVERDOSAGE. 2008. Read the source