Menthol

What it is

Menthol is a monoterpene alcohol with a cooling smell and taste. The medicinally active isomer is l-menthol, which is described as presenting "the characteristic peppermint scent" and as being "responsible for the cooling sensation when applied to nasal mucosal surfaces because of stimulation of trigeminal cold receptors". In the United States it is one of only two ingredients the FDA's over-the-counter antitussive monograph allows for topical use, alongside camphor, and it is also permitted in lozenges.

What the research says

Menthol's best-documented effect is on sensation rather than on airflow: the human studies here found it made the nose feel clearer while measured nasal airflow, nasal resistance and upper airway resistance showed no change - though each of those studies was small, and some used an aromatic comparator rather than an inert placebo, so they are failures to detect a change rather than proof of none. Randomised challenge studies do show menthol raises the cough threshold to inhaled irritants, and a randomised trial in COPD found inhaled menthol lowered breathlessness ratings during exercise without changing ventilation or endurance time. Topically it reduced some specific pains in small trials, and a meta-analysis found a small performance benefit during exercise driven by perceived cooling, with core temperature unchanged. Against that, laboratory work on airway cells at electronic-cigarette concentrations and a survey of cough-drop users raise questions about heavy or repeated exposure.

Evidence grade: Disputed.

How it works

Drug class: Monoterpene alcohol used as an over-the-counter topical antitussive (cough suppressant), external analgesic / counterirritant and lozenge; an agonist of the cold-sensing TRPM8 ion channel

Menthol switches on TRPM8, the cold-sensing ion channel in sensory nerve endings, which is why it feels cold without lowering temperature. Work in guinea pigs localises its cough-suppressing action to TRPM8-bearing trigeminal nerve endings in the nose: menthol vapour applied to the upper airway suppressed cough triggered in the windpipe, while menthol put directly on the windpipe did nothing, so the effect is a reflex started in the nose rather than a local action on the airway. (Source 1)

What it is used for

• Randomised challenge studies show menthol raises the amount of inhaled irritant needed to provoke a cough, in adults and in people with chronic cough. But in the one study here that counted actual coughs in children, the reduction after menthol was no different from the reduction after the comparator, which was eucalyptus oil rather than an inert placebo. The vapour-rub trial that found a benefit tested a camphor-menthol-eucalyptus mixture, not menthol alone. Evidence: limited. (Source 2)
• This is the clearest does-not-support position for menthol. The four human studies cited here measured nasal airflow, nasal resistance or upper airway resistance objectively and none of them detected a change, while subjective ratings of nasal patency improved; all four were small, and three had no control group or an active aromatic comparator, so they are failures to detect a change rather than proof of none. Menthol is not among the nasal decongestant active ingredients the US monograph lists; it is listed as a topical antitussive. Evidence: not-supported. (Source 3)
• Approved as an external analgesic. One small randomised trial found 30% topical menthol reduced propofol injection pain; an uncontrolled retrospective chart review in refractory neuropathic pain found 12 of 21 patients met a permissive response threshold on cream titrated to 10%. There is no large randomised trial of menthol alone for musculoskeletal pain in the literature we reached, and the bibliometric survey of this literature found only 15 clinically relevant human papers in one PubMed search covering 2010 to 2022. Evidence: limited. (Source 4)
• Off-label. A randomised crossover trial in 20 people with COPD found menthol added to the breathing circuit lowered breathlessness ratings during cycling, while exercise endurance time and the ventilatory and neuromuscular measurements showed no difference. With 20 patients that is a failure to detect a difference rather than a demonstration of none, and the authors conclude only that menthol "may be useful" in selected patients. Evidence: limited. (Source 5)
• Off-label. A 2026 systematic review and three-level meta-analysis of 16 studies and 191 participants found a small performance benefit and clear reductions in thermal sensation and perceived exertion, with core temperature unchanged; the effect was not statistically significant in hot conditions. Evidence: limited. (Source 6)

Interactions

• Warfarin (case reports): A 2005 case report describes the INR falling in a man on warfarin who had been using menthol cough drops, with the warfarin dose returned to its previous amount after he stopped them; a 2010 report describes a second, separate case. The 2005 report does not say how many drops a day he used. The proposed mechanism is an effect of menthol on cytochrome P450 enzymes and on drug absorption, which was not demonstrated in either patient. This is case-report evidence only. (Source 7)
• Alcohol (theoretical): We found no clinical trial, pharmacokinetic study or case report of an interaction between topical or inhaled menthol and alcohol. The literature on this route is small: one PubMed search covering 2010 to 2022 retrieved 103 records on topical camphor- and menthol-containing agents, of which 15 were clinically relevant human papers, after excluding non-human studies, misuse and ingestion reports and intraoral, intranasal and ophthalmic products. (Source 8)
• Tobacco smoke and e-cigarette aerosol (clinical trial): Several of the menthol studies themselves raise this. Because menthol blunts the cough reflex and the sensation of irritation, the authors of the chronic-cough challenge study argue it could conceal the natural irritation of smoking. In cultured human airway cells, menthol at electronic-cigarette strengths impaired mucociliary clearance through TRPM8. (Source 9)
• Camphor and eucalyptus oil in the same product (label): Menthol is usually sold in combination in US cough rubs: the leading label combines menthol 2.6% with camphor (synthetic) 4.8% and eucalyptus oil 1.2%. The vapour-rub trial and the ferret airway study therefore tested a mixture, and no human trial isolates menthol's own contribution to that product's effect. (Source 10)
• Dietary supplements (theoretical): We found no human study of an interaction between menthol and any dietary supplement. The nearest documented interaction is the warfarin case-report pair, which concerns a prescription drug, not a supplement; the proposed cytochrome P450 mechanism in those reports is the only route by which a supplement interaction would be expected, and it has not been tested. (Source 11)

Stopping it

• No dependence or withdrawal syndrome for menthol is described in the literature we searched. What is documented is that stopping heavy cough-drop use changed a measurable outcome: in the 2010 warfarin case report the INR rose from 1.6 to 2.9 within five days of the drops being stopped. (Source 11)
• In the earlier, separate 2005 case report the warfarin dose was put back to its previous amount after the menthol cough drops were stopped and the INR stayed stable. That report records no number of drops a day. (Source 7)
• A survey of cough-drop users found heavier daily menthol intake associated with worse cough, and the authors recommend asking about cough-drop use in people whose cough persists - which implies reducing intake rather than tapering a drug. This is an association in a cross-sectional survey, not a withdrawal study. (Source 12)

What goes wrong

In a survey of primary-care patients with cough, higher daily menthol intake from cough drops was independently associated with worse cough severity. (Source 12)

• Survey study, Very low certainty.
• Size: 548 surveys analysed; 363 (66.2%) reported using cough drops, of whom the source reports 269 as menthol users and prints that as 90%.
• Who: adolescent and adult outpatients attending five Wisconsin primary care clinics for acute or subacute cough.
• How long: cross-sectional survey, April 2016 to May 2017.
• Result: Cough severity correlated with average menthol dose per drop (R = 0.19; P = .007), number of drops per day (R = 0.2; P = .002) and total daily menthol (R = 0.21; P = .001), still significant (P = .003) after adjusting for age, sex, smoking, season and site. These correlations are very weak - an R of about 0.2 is around 4% of the variation. The abstract's own univariate comparison of menthol against non-menthol drops found no difference in severity (P = .65) or duration (P = .17). This is an association, not a demonstration of cause, and the survey cannot rule out the reverse explanation, that a worse or longer cough leads people to eat more cough drops.
• Funding: not stated.

Limit of this finding: The source prints an arithmetic impossibility: 269 of 363 cough-drop users is 74.1%, not the 90% it states; for 269 to be 90% the denominator would have to be about 299. The 66.2% of 548 is sound. The figure is quoted as the source printed it and should not be read as 90% of the 363.

However, significant independent associations were found between cough severity and 1) average menthol dose per cough drop (R = 0.19; P = .007), 2) number of cough drops consumed daily (R = 0.2; P = .002) and 3) total amount of menthol consumed per day (R = 0.21; P = .001) that remained significant (P = .003) after controlling for age, sex, smoking status, season, and clinic site.

In cultured human airway cells, nebulised menthol slowed cilia, thickened mucus and raised inflammatory gene expression through TRPM8, impairing mucociliary clearance. (Source 13)

• Lab study in cells, Very low certainty.
• Size: air-liquid interface cultures of primary human airway epithelial cells.
• Who: cell culture, menthol at e-cigarette concentrations.
• How long: 24 hours.
• Result: Basolateral menthol 1 mM significantly decreased ciliary beat frequency and airway surface liquid volume at 24 h; nebulised menthol reduced ciliary beat frequency, increased mucus concentration and reduced mucociliary transport, and raised MUC5AC, IL1B and TNFA; a TRPM8 antagonist blocked these effects.
• Funding: grant-supported (grants list present)

Nebulized menthol further increased the expression of mucin 5AC (MUC5AC) and mRNA expression of the inflammatory cytokines IL1B and TNFA. Menthol activated TRPM8, and the effects of menthol on MCC and inflammation could be blocked by a specific TRPM8 antagonist.

In ferret airway, a menthol-containing vapour rub increased mucin secretion and slowed the cilia in excised tissue, and raised mucus transport velocity in airways already inflamed with endotoxin; this is animal and tissue work on the combination product. (Source 14)

• Animal study, Very low certainty.
• Size: tracheas from 15 healthy ferrets plus anaesthetised ferrets.
• Who: ferret trachea, prompted by a toddler who developed respiratory distress after the rub was applied under her nose.
• How long: acute exposure.
• Result: Mucin secretion +63% versus controls in vitro (p < 0.01); ciliary beat frequency -35% (p < 0.05); mucociliary transport velocity +34% in endotoxin-inflamed airways (p = 0.002). The authors' harm inference is explicitly conditional: the pattern resembles irritant exposure and "may lead to" mucus obstruction of small airways and increased nasal resistance, neither of which was measured.
• Funding: not stated.

¹ Mucin secretion was increased by 63% over the controls in the VVR in vitro group (p < 0.01). CBF was decreased by 35% (p < 0.05) in the VVR group.

A case report describes the INR falling in a man taking warfarin while using 8 to 10 menthol cough drops a day, and rising again within five days of stopping them; its authors note it is the second such case report published. (Source 11)

• Case report, Very low certainty.
• Size: 1 patient (46-year-old man)
• Who: an adult on warfarin for venous thromboembolism using 8 to 10 menthol cough drops a day.
• How long: several weeks.
• Result: INR fell from 2.6 to 1.6 and stayed there for 3 weeks despite warfarin increases; five days after the cough drops were stopped the INR rose from 1.6 to 2.9, and the weekly warfarin dose was eventually reduced from 50 mg to 40 mg. The Naranjo scale rated the reaction probable. The report says only that this is the second published case of a warfarin-menthol interaction; it gives no dose, direction or outcome for the earlier one.
• Funding: not stated.

Five days after discontinuing the cough drops, his INR increased from 1.6 to 2.9. Over the subsequent 5 weeks, his INR was stabilized at a much lower weekly warfarin dose of 40 mg.

The monograph requires menthol ointments to carry an external-use-only warning and, in bold, a warning not to heat or microwave the product or add it to hot water because it may splatter and cause burns. (Source 15)

• Official position, Certainty not rated.
• Size: not applicable.
• Who: US over-the-counter products containing menthol.
• How long: text as printed in the 2024 CFR edition.
• Result: The same warnings apply to camphor and menthol ointments alike, and the monograph requires the directions to open with a bold cross-reference to them.
• Funding: not applicable.

“For external use only. Do not take by mouth or place in nostrils.”

What the evidence supports

Inhaling menthol vapour significantly raised the capsaicin cough threshold in adults, while a bitter substance given as a mouth rinse did not, which the authors offer as a demonstration of specificity. (Source 2)

• Randomized trial, Low certainty.
• Size: not stated in the abstract; three small within-subject crossover experiments.
• Who: adults undergoing single-inhalation capsaicin cough challenge in a laboratory; the abstract does not state how many, and the menthol experiment was a within-subject crossover rather than a parallel-group trial.
• How long: acute, within-session.
• Result: Rinsing with sucrose and inhaling menthol vapour both significantly increased measured cough thresholds; sucrose octaacetate, given as a bitter mouth rinse, produced a non-significant decrease.
• Funding: listed as Research Support, Non-U.S. Gov't and Research Support, N.I.H., Extramural.

Limit of this finding: The quotation keeps the source's own misspelling of sucrose octaacetate as "sucrose octaacete"; that is how the abstract prints it and it has not been corrected. Note also that the bitter control was a mouth rinse while menthol was inhaled vapour, so it does not control for the inhaled route.

Rinsing with sucrose and inhaling menthol vapor significantly increased measured cough thresholds. Rinsing with sucrose octaacete caused a non-significant decrease in cough thresholds, an important demonstration of specificity.

In patients with chronic cough, nebulised 1% menthol raised the capsaicin cough threshold compared with placebo, and peak inspiratory flow fell after placebo but not after either menthol strength. (Source 9)

• Randomized trial, Low certainty.
• Size: 14 patients with chronic cough and 15 control subjects.
• Who: adults with chronic cough and airway sensitivity to environmental irritants, plus healthy controls.
• How long: three visits in a randomised, double-blind order; a crossover challenge study.
• Result: After 1% menthol, patients' cough thresholds were significantly higher than after placebo (P < 0.02) and than after 0.5% menthol (P < 0.05). Peak inspiratory flows were reduced after placebo but not after 0.5% or 1% menthol; forced inspiratory flow at 50% was lowered after placebo and after 0.5% menthol (P < 0.05) but not after 1% menthol.
• Funding: listed as Research Support, Non-U.S. Gov't.

After inhalation of 1% menthol, the patients' cough thresholds were significantly higher (P < 0.02) compared to after placebo inhalation and to after 0.5% menthol inhalation (P < 0.05).

In a four-arm randomised trial, 30% topical menthol reduced the incidence of propofol injection pain compared with its solvent. (Source 4)

• Randomized trial, Low certainty.
• Size: 120 patients randomised to four groups.
• Who: patients receiving intravenous propofol.
• How long: single application 15 minutes before injection.
• Result: Pain incidence 13% with menthol versus 40% with solvent, P = .020; pain intensity also lower, P = .021. Skin cooling alone gave 27% versus 52%, P = .049.
• Funding: not stated.

The incidence of propofol injection-induced pain in the menthol group was significantly lower than that in the solvent group (13% vs 40%, P = .020). The pain intensity in the menthol group was lower than that in the solvent group (P = .021).

In an uncontrolled, retrospective, multicentre chart review of refractory localised neuropathic pain, 12 of 21 patients met a permissive response threshold on compounded menthol cream titrated to 10%. (Source 16)

• Case series, Very low certainty.
• Size: 21 patients analysed (76% women; 71% with chemotherapy-induced peripheral neuropathy)
• Who: adults in two French pain centres with localised neuropathic pain, baseline pain above 4/10 and prior treatment failure; a retrospective chart review with no control arm, which the authors themselves call exploratory.
• How long: titration from 1% to 10% over approximately 60 days.
• Result: Mean pain intensity fell from 6.83 at baseline to 4.82 at 10%, with significant improvement from 3% onward; 12 of 21 (57%) met the response criterion at 10%, defined permissively as a 30% or greater fall in pain score and/or 30% or greater self-reported relief. Adverse effects were mostly mild, transient and local. No control group, no blinding, retrospective data, and the authors call for randomised placebo-controlled trials.
• Funding: not stated.

Mean pain intensity decreased from 6.83 at baseline to 4.82 at 10%, with significant improvement from 3% onward. At 10%, 12/21 patients met the response criterion.

In guinea pigs, menthol suppressed cough only when given as vapour to the nose, not when applied to the windpipe, indicating the antitussive effect is a nasal reflex. (Source 1)

• Animal study, Very low certainty.
• Size: conscious and anaesthetised guinea pigs (number not stated in the abstract)
• Who: guinea pigs with cough evoked by citric acid on the tracheal mucosa.
• How long: acute.
• Result: Cough was suppressed by menthol only when administered as vapours to the upper airways; menthol on the tracheal mucosa, or as vapour or aerosol to the lower airways, had no effect; the inactive (+)-menthol isomer did not work; TRPM8 was found in nasal trigeminal afferents that do not co-express TRPA1 or TRPV1.
• Funding: grant-supported (grants list present)

In anesthetized guinea pigs, cough evoked by citric acid applied topically to the tracheal mucosa was suppressed by menthol only when it was selectively administered as vapors to the upper airways.

The US FDA's over-the-counter antitussive monograph, as codified in the 2024 Code of Federal Regulations, permits menthol as a topical antitussive at 2.6 to 2.8 percent in an ointment and, separately, at 5 to 10 mg in a lozenge. (Source 17)

• Official position, Certainty not rated.
• Size: not applicable.
• Who: US over-the-counter products.
• How long: monograph first issued 52 FR 30055, Aug. 12, 1987, as amended to 67 FR 4907, Feb. 1, 2002; text as printed in the 2024 CFR edition.
• Result: The ointment contains 2.6 to 2.8 percent menthol, is rubbed on throat and chest and used up to three times daily. The lozenge is a different dosage form with its own directions: it contains 5 to 10 mg menthol, is allowed to dissolve slowly in the mouth, and may be repeated every hour as needed. Both tell children under 2 years to consult or ask a doctor. A further subparagraph sets 3.2 percent menthol for steam inhalation.
• Funding: not applicable.

The product contains 2.6 to 2.8 percent menthol.

What the evidence does not support

In a single-arm before-and-after study of 18 healthy volunteers, menthol inhalation did not produce a detectable change in nasal mucosal temperature or in measured nasal airflow, yet 16 of the 18 said their breathing had improved. (Source 18)

• Case series, Very low certainty.
• Size: 18 healthy volunteers, mean age 30 years.
• Who: healthy adults; no control group, no placebo arm and no randomisation.
• How long: before-and-after measurement around a single inhalation.
• Result: Mean end-inspiratory mucosal temperature 27.7 degrees C (+/-4.0) before and 28.5 degrees C (+/-3.5) after, p > 0.05 - a rise of 0.8 degrees C on the point estimate that did not reach significance; no significant change in rhinomanometry; 16 of 18 reported improved nasal breathing on a visual analogue scale.
• Funding: not stated.

Limit of this finding: This is a failure to detect a change in 18 people, not a demonstration that menthol changes nothing. There was no control group and no power calculation, the dispersion is wide, and the temperature in fact rose slightly on the point estimate.

There were no statistically significant differences between the temperature values before and after menthol inhalation (p > 0.05). In addition, no statistically significant differences between the rhinomanometric values before and after menthol inhalation were observed. Sixteen of the 18 subjects reported an improvement of nasal breathing after menthol inhalation by means of the VAS.

Menthol applied to the palate increased the sensation of nasal airflow without changing measured nasal resistance, and local anaesthesia of the nerve abolished the sensation while leaving the measurement unchanged. (Source 19)

• Case series, Very low certainty.
• Size: not stated in the abstract.
• Who: human volunteers with menthol applied to the palatal mucosa; an uncontrolled within-subject experiment with no randomisation, no placebo and no control group, and the abstract gives no participant count.
• How long: before-and-after within a session.
• Result: Enhanced sensation of airflow with nasal resistance unaffected; after local anaesthesia of the palatine nerve or the nasal mucosa the subjective response was substantially diminished while objective patency still did not change. The authors put their mechanism forward as a suggestion, not a demonstration.
• Funding: not stated.

L-Menthol stimulation of the palatal mucosa enhanced nasal sensation of airflow but nasal resistance was unaffected. By contrast, L-menthol stimulation after local anesthesia of the palatine nerve or of the nasal mucosa substantially diminished the subjective response of increased nasal patency but without affecting objective nasal patency.

In a randomised, sham-controlled, single-blinded crossover study in 10 healthy young adults, inhaled menthol did not change upper airway resistance. (Source 20)

• Randomized trial, Very low certainty.
• Size: 10 healthy participants (8 female), mean age 21 +/- 1.6 years.
• Who: healthy young adults, semirecumbent quiet breathing.
• How long: single session per condition, crossover, single-blinded.
• Result: Upper airway resistance 3.47 +/- 0.32 cmH2O/L/s with menthol versus 3.27 +/- 0.28 with sham, P = 0.33. The abstract also reports no differences in respiratory frequency, minute ventilation or inspiratory time fraction. There was no sample-size justification, and the participants had no congestion.
• Funding: listed as Research Support, Non-U.S. Gov't.

Limit of this finding: Two cautions. With 10 healthy young people and no power calculation this is an absence of evidence rather than evidence of no effect. And the source prints a resistance unit, cmH2O/L/s, against its respiratory frequency, minute ventilation and inspiratory-time-ratio figures, where it is physically impossible; that is the journal's error, reproduced here unaltered, and only the upper-airway-resistance figures legitimately carry that unit - which is why they are the only ones quoted.

The upper airway resistance was similar during menthol (3.47±0.32 cmH2O⁄L⁄s) and sham (3.27±0.28 cmH2O⁄L⁄s) (P=0.33) inhalation.

Menthol is not among the nasal decongestant active ingredients the US monograph lists, either for oral or for topical use, although the same part of the regulation lists it as a topical antitussive. (Source 21)

• Official position, Certainty not rated.
• Size: not applicable.
• Who: US over-the-counter products.
• How long: text as printed in the 2024 CFR edition; section last amended 71 FR 43362, Aug. 1, 2006.
• Result: The monograph's topical nasal decongestant list is levmetamfetamine, ephedrine and its hydrochloride and sulfate, a reserved entry, naphazoline hydrochloride, oxymetazoline hydrochloride, phenylephrine hydrochloride, propylhexedrine and xylometazoline hydrochloride. Menthol appears nowhere in it.
• Funding: not applicable.

(b) Topical nasal decongestants. (1) Levmetamfetamine. (2) Ephedrine. (3) Ephedrine hydrochloride. (4) Ephedrine sulfate. (5) [Reserved] (6) Naphazoline hydrochloride. (7) Oxymetazoline hydrochloride. (8) Phenylephrine hydrochloride. (9) Propylhexedrine. (10) Xylometazoline hydrochloride.

Where the evidence is mixed

In healthy children, inhaled menthol made the nose feel significantly clearer but changed none of the measured airflows, and the fall in cough count after menthol was no different from the fall after the comparator, which was eucalyptus oil rather than an inert placebo. (Source 3)

• Randomized trial, Low certainty.
• Size: 42 healthy children aged 10 and 11.
• Who: schoolchildren without rhinitis.
• How long: single-blind pseudo-randomised crossover, with baseline and post-inhalation measurements on each of two consecutive days.
• Result: No effect on any spirometric measurement; perception of nasal patency improved (mean difference in log VAS menthol minus placebo -0.207, 95% CI -0.329 to -0.085, where a lower score meant a clearer nose, so the negative number is an improvement as the source describes it); cough count difference versus the comparator -1.71, 95% CI -4.11 to 0.69, that is, not significant.
• Funding: listed as Research Support, Non-U.S. Gov't.

Limit of this finding: Two things the paper's own wording requires. The comparator the source calls "placebo" was eucalyptus oil, itself an aromatic volatile with claimed nasal effects, so a null against it is weaker than a null against an inert control. And the visual-analogue difference is printed as a negative number yet described as an increase in patency, because on that scale a lower score meant a clearer nose; the sign is the source's and has not been altered.

There was no effect of menthol on any of the spirometric measurements. Following menthol, there was a significant increase in the perception of nasal patency (mean difference in log VAS (menthol-placebo) = -0.207, 95%CI -0.329, -0.085). The cough count after menthol inhalation was reduced when compared to baseline but the change was not different from that after placebo (mean difference in cough count (menthol-placebo) = -1.71, 95%CI -4.11, 0.69).

In a randomised crossover trial in COPD, inhaled menthol lowered breathlessness ratings during cycling but left endurance time, ventilation and neuromuscular measures unchanged. (Source 5)

• Randomized trial, Low certainty.
• Size: 20 patients with COPD (60% male; mean age 68 +/- 6 years; FEV1 47% +/- 17% predicted)
• Who: people with COPD performing constant-load cycle exercise to exhaustion.
• How long: two exercise tests on separate days, counterbalanced order.
• Result: Serial dyspnoea intensity lower with menthol (estimate -0.09 per 10% peak time; 95% CI -0.15 to -0.02; P = .01); endurance time unchanged (delta 0.3 +/- 1.6 minutes; P = .50); 85% reported easier inspiratory airflow with menthol; no differences in ventilatory or neuromuscular parameters.
• Funding: grant-supported (grants list present); registered on ClinicalTrials.gov as NCT05785026, taken from the record's registration field rather than from the held abstract text.

Limit of this finding: In a 20-patient crossover trial, "no differences in ventilatory and neuromuscular parameters" and an unchanged endurance time mean the trial did not detect a difference, not that menthol changes nothing; the authors' own conclusion is hedged, that menthol "may be useful" in selected patients.

Exercise endurance time was unaffected by menthol (Δ 0.3 ± 1.6 minutes with menthol vs placebo; P = .50). A total of 85% reported easier inspiratory airflow with menthol.

A 2026 systematic review and meta-analysis found topical menthol gave a small improvement in exercise performance driven by perceived cooling, with core body temperature unchanged and no significant effect in hot conditions. (Source 6)

• Meta-analysis, Low certainty.
• Size: 16 studies involving 191 participants.
• Who: randomised or controlled trials of acute topical menthol during exercise.
• How long: acute application during single exercise bouts.
• Result: Performance g = 0.27, p = 0.02; thermal sensation g = -0.74; perceived exertion g = -0.35; thermal comfort g = 0.34; core body temperature unchanged; effects in environments at or above 30 degrees C were smaller and not statistically significant.
• Funding: not stated.

Topical menthol produced a small but significant improvement in exercise performance (g = 0.27, p = 0.02). Thermal sensation (g = -0.74) and perceived exertion (g = -0.35) were reduced, with a small improvement in thermal comfort (g = 0.34), whereas core body temperature was unchanged.

Where the research disagrees

Whether menthol actually opens the nose or only makes it feel open

• Lindemann and colleagues, who measured nasal mucosal temperature and airflow directly, single-arm before-and-after rhinomanometry and thermocouple measurement in 18 healthy volunteers, with no control group, placebo or randomisation; three other studies in this entry reach the same conclusion by spirometry in 42 children, by rhinometry after palatal application and by upper airway resistance measurement in a randomised sham-controlled crossover: "Menthol inhalation does not have an effect on nasal mucosal temperature and nasal airflow. The subjective impression of an improved nasal airflow supports the fact that menthol leads to a direct stimulation of cold receptors modulating the cool sensation, entailing the subjective feeling of a clear and wide nose." (Source 18)
• The same literature on the subjective side, single-blind pseudo-randomised crossover trial in 42 healthy children: "Menthol has no effect on objective measures of flow but significantly increases the perception of nasal patency." (Source 3)

Whether menthol helps a cough or can make it worse

• Investigators of capsaicin cough-challenge trials, randomised double-blind crossover challenge study in 14 patients with chronic cough and 15 controls: "In patients with chronic cough, pre-inhalation of menthol reduces cough sensitivity to inhaled capsaicin and influences inspiratory flows. The findings may provide scientific support for the common practice of using menthol as a reliever for variant airway discomfort." (Source 9)
• Primary-care investigators who surveyed cough-drop users, cross-sectional survey of 548 patients, with adjusted correlations only, no randomisation and no control for reverse causation: "Cough severity in some individuals may be negatively influenced by the amount of menthol consumed via cough drops." (Source 12)
• Investigators who counted coughs rather than thresholds in children, single-blind pseudo-randomised crossover trial in 42 healthy children with citric-acid cough challenge: "The cough count after menthol inhalation was reduced when compared to baseline but the change was not different from that after placebo (mean difference in cough count (menthol-placebo) = -1.71, 95%CI -4.11, 0.69)." (Source 3)

How much

• Reference intake: There is no prescriber-set dose: this is an over-the-counter product whose amount is fixed by the Drug Facts label. The US FDA monograph position, as printed in 21 CFR 341.74(d)(2)(ii) in the 2024 Code of Federal Regulations, is that a menthol ointment for cough contains 2.6 to 2.8 percent menthol, is rubbed on the throat and chest in a thick layer, used up to three times daily, and is not for children under 2 years without a doctor. (Source 17)
• Upper limit: There is no systemic daily maximum for the topical route. The marketed US label for the leading product states menthol 2.6%, directs that it not be used in children under 2 years, and for the muscle-and-joint use says to apply to the affected area not more than 3 to 4 times daily. (Source 10)
• Studied: The chronic cough trial gave 1 mL of nebulised menthol solution at 0.5% or 1%, against a placebo of saline with 0.05% menthol. (Source 9)
• Studied: The neuropathic pain series used pharmacy-compounded menthol cream titrated from 1% to 10% over about 60 days. (Source 16)
• Studied: The propofol-pain trial applied 30% menthol to the forearm 15 minutes before injection. (Source 4)
• Studied: The airway cell-culture harm study used menthol at 1 mM basolaterally and nebulised menthol onto the apical surface, concentrations the authors chose to simulate electronic-cigarette exposure. (Source 13)
• Studied: The monograph's lozenge subparagraph sets 5 to 10 mg menthol per lozenge, allowed to dissolve slowly in the mouth and repeatable every hour as needed; this is a regulatory position, not a trial dose. (Source 17)

A common belief, and what the research shows

The belief: Menthol clears a blocked nose.

What the research shows: It changes the sensation, not the airflow. Measured with a thermocouple and rhinomanometry, "no statistically significant differences between the rhinomanometric values before and after menthol inhalation were observed" while "Sixteen of the 18 subjects reported an improvement of nasal breathing after menthol inhalation by means of the VAS." The children's trial reached the same conclusion: "Menthol has no effect on objective measures of flow but significantly increases the perception of nasal patency." A randomised, sham-controlled, single-blinded crossover in 10 healthy adults measuring upper airway resistance also found "Inhalation of menthol does not alter upper airway resistance in awake human subjects."

Questions and answers

What is it?

Menthol is a monoterpene alcohol - the cooling compound of mint. The form used medicinally is l-menthol, which carries the peppermint smell and produces the cold feeling by stimulating trigeminal cold receptors rather than by lowering any temperature. (Source 18)

What does it do in the body?

Menthol switches on TRPM8, the cold-sensing channel in sensory nerves, so it feels cold without making anything colder. Animal work places its cough-suppressing action in TRPM8-bearing nerve endings in the nose: menthol vapour to the nose suppressed cough triggered in the windpipe, while menthol placed on the windpipe itself did nothing. In other words it works through a reflex from the nose, not by acting on the lungs. (Source 1)

Is it good or bad for you?

Both, depending on the amount and the route. At the strengths in ointments and lozenges it raises the cough threshold in randomised challenge studies and reduces some pains, and a meta-analysis found a small exercise benefit from perceived cooling. At much higher exposures it looks harmful: at e-cigarette concentrations in cultured human airway cells it slowed cilia, thickened mucus and raised inflammatory genes, and heavier daily cough-drop menthol was associated with worse cough in a survey. (Source 13)

How do you get more of it?

Menthol is a medicine, not a nutrient, so there is no reason to seek more of it. The US monograph describes two dosage forms: an ointment at 2.6 to 2.8 percent rubbed on throat and chest up to three times daily, and a lozenge containing 5 to 10 mg that is allowed to dissolve slowly in the mouth and may be repeated every hour as needed. Trials have also used nebulised solutions at 0.5% and 1% and compounded creams up to 10%. These are descriptions of what exists and what has been studied, not recommendations. (Source 17)

If it is harmful, what reduces it?

Where menthol itself appears to be doing harm, the published response is to reduce or stop the exposure rather than to treat it. The authors of the cough-drop survey advise taking a history of cough-drop use in people whose cough persists, and call for research into the mechanism. There is no antidote and nothing to taper. (Source 12)

Why might someone be low in it or missing it?

Does not apply: menthol is not a nutrient and there is no deficiency state. What does vary between people is how much of its effect they feel, and that effect is subjective - the same literature reports an increased sense of nasal airflow without objectively measurable change. In one study the subjective increase in nasal patency after oral menthol depended on the person's sense of smell, with little or no effect in those with poorer olfactory function. (Source 22)

Which whole foods contain it or feed it?

Mint plants are the natural source of menthol, and the medicinal compound is described as a natural herbal compound whose l-isomer carries the peppermint scent. But food amounts of mint are not the same as the concentrations used in rubs, lozenges or trial creams, and no study in this literature tests dietary mint against a medicinal menthol product. (Source 18)

What happens if you do not have it?

Nothing happens; there is no menthol deficiency. Not using menthol means forgoing a sensory effect whose measured benefit is narrow. In the COPD trial, breathlessness ratings improved and 85% said inspiratory airflow felt easier, yet exercise endurance time was unchanged and the ventilatory and neuromuscular measurements showed no difference - with 20 patients, that is a failure to detect a difference rather than proof there is none. (Source 5)

How can you test for it?

There is no clinical test for a person's menthol status, and none would be meaningful. What the research literature measures instead is menthol's effect: the capsaicin or citric-acid cough challenge used to find a cough threshold, rhinomanometry or spirometry for airflow, and a visual analogue scale for the feeling of a clear nose. Those are research tools for studying the drug, not diagnostic tests, and they are not standardised for clinical use. (Source 3)

We searched: Europe PMC searches for menthol with nasal patency and airflow, menthol with cough, menthol with airway and infant, and menthol pharmacokinetics; no validated clinical assay for menthol exposure or status appeared.

References

1. Journal of applied physiology (Bethesda, Md. : 1985). The role of trigeminal nasal TRPM8-expressing afferent neurons in the antitussive effects of menthol. 2013. PMID 23640596, DOI 10.1152/japplphysiol.01144.2012. Read the source
2. Pulmonary pharmacology & therapeutics. Sweet taste and menthol increase cough reflex thresholds. 2012. PMID 22465565, DOI 10.1016/j.pupt.2012.03.005. Read the source
3. Pediatric pulmonology. Does inhaling menthol affect nasal patency or cough?. 2008. PMID 18435479, DOI 10.1002/ppul.20797. Read the source
4. Medicine. Skin cooling and topical application of menthol can reduce propofol injection-induced pain, a randomized trial. 2025. PMID 40527818, DOI 10.1097/md.0000000000042809. Read the source
5. Chest. Inhaled Menthol for Dyspnea Relief During Cycle Exercise in COPD: A Randomized Trial (abstract; the section headings are Europe PMC's Title Case rendering, not the publisher's, which sets them in capitals; the NLM-indexed trial-registration block, which the indexer split into a spurious 'Clinicaltrials' section, is not held). 2025. PMID 40088943, DOI 10.1016/j.chest.2025.03.002. Read the source
6. Journal of thermal biology. Acute topical menthol application and exercise performance: A systematic review and meta-analysis of perceptual and physiological responses. 2026. PMID 42385298, DOI 10.1016/j.jtherbio.2026.104529. Read the source
7. The Annals of pharmacotherapy. Possible warfarin interaction with menthol cough drops. 2005. PMID 15644472, DOI 10.1345/aph.1e537. Read the source
8. Cureus. Looking Back to Move Forward: The Current State of Research on the Clinical Applications of Camphor- and Menthol-Containing Agents. 2023. PMID 37546095, DOI 10.7759/cureus.41426. Read the source
9. Respiratory medicine. Inhalation of menthol reduces capsaicin cough sensitivity and influences inspiratory flows in chronic cough. 2013. PMID 23266255, DOI 10.1016/j.rmed.2012.11.017. Read the source
10. DailyMed (US National Library of Medicine); labeler Procter & Gamble, Cincinnati OH; NDC 58933-544. VICKS VAPORUB (camphor (synthetic), eucalyptus oil, and menthol) ointment - US Drug Facts label, sections Active ingredients through Other information, including the Purpose section whose heading the labeler mis-typed as "Inactive ingredients Purpose". 2026. Read the source
11. Pharmacotherapy. Probable warfarin interaction with menthol cough drops. 2010. PMID 20030479, DOI 10.1592/phco.30.1.110. Read the source
12. Journal of the American Board of Family Medicine : JABFM. Menthol Cough Drops: Cause for Concern?. 2018. PMID 29535234, DOI 10.3122/jabfm.2018.02.170363. Read the source
13. International journal of molecular sciences. Nebulized Menthol Impairs Mucociliary Clearance via TRPM8 and MUC5AC/MUC5B in Primary Airway Epithelial Cells. 2023. PMID 36675209, DOI 10.3390/ijms24021694. Read the source
14. Chest. Vicks VapoRub induces mucin secretion, decreases ciliary beat frequency, and increases tracheal mucus transport in the ferret trachea. 2009. PMID 19136404, DOI 10.1378/chest.08-0095. Read the source
15. US Government Publishing Office, Code of Federal Regulations. 21 CFR 341.74(c)(5) Warnings for topical antitussives containing camphor or menthol - subparagraphs (i)-(vi) and the bullet-symbol footnote, 2024 annual edition. 2024. Read the source
16. Journal of pain & palliative care pharmacotherapy. Topical Menthol Cream for Refractory Localized Neuropathic Pain: A Multicenter Retrospective Study. 2026. PMID 42627361, DOI 10.1080/15360288.2026.2709501. Read the source
17. US Government Publishing Office, Code of Federal Regulations. 21 CFR 341.74(d) Directions for antitussive drug products - paragraph (d) lead-in, (d)(1)(i)-(v) oral antitussives and (d)(2)(i)-(iii) topical antitussives containing camphor or menthol (ointment and lozenge), 2024 annual edition. 2024. Read the source
18. American journal of rhinology. Impact of menthol inhalation on nasal mucosal temperature and nasal patency. 2008. PMID 18702906, DOI 10.2500/ajr.2008.22.3194. Read the source
19. Auris, nasus, larynx. The effect of L-menthol stimulation of the major palatine nerve on subjective and objective nasal patency. 1997. PMID 9134138, DOI 10.1016/s0385-8146(96)00005-3. Read the source
20. Canadian respiratory journal. The effect of inhaled menthol on upper airway resistance in humans: a randomized controlled crossover study. 2013. PMID 23457678, DOI 10.1155/2013/383019. Read the source
21. US Government Publishing Office, Code of Federal Regulations. 21 CFR 341.20 Nasal decongestant active ingredients - whole section, 2024 annual edition. 2024. Read the source
22. Acta oto-laryngologica. Subjective changes in nasal patency after chewing a menthol-containing gum in patients with olfactory loss. 2015. PMID 25622621, DOI 10.3109/00016489.2014.980913. Read the source