Doxazosin

What it is

Doxazosin is a quinazoline-derived medicine that blocks alpha-1 adrenergic receptors, the switches that noradrenaline uses to tighten smooth muscle in blood vessels, the prostate and the bladder neck. Blocking them relaxes that muscle, which lowers blood pressure and eases the outflow obstruction of an enlarged prostate. It is taken once a day as tablets, with a long elimination half-life of about 22 hours, and is cleared mainly by the liver through CYP3A4. It is approved both for the symptoms of benign prostatic hyperplasia and for high blood pressure.

What the research says

Doxazosin works for prostate symptoms and lowers blood pressure, but the outcome evidence splits sharply between those two uses. In MTOPS, 3,047 men followed a mean 4.5 years, doxazosin cut the risk of overall clinical progression of benign prostatic hyperplasia by 39%, although it did not reduce acute urinary retention or the need for invasive treatment. In hypertension the drug lowers blood pressure by roughly 10/8 mmHg standing, yet ALLHAT compared it head to head against a cheap diuretic in 24,335 high-risk patients and the doxazosin arm was stopped early: heart failure was doubled and combined cardiovascular disease was 25% higher, with no difference in heart attack or total death. Off-label, a meta-analysis supports it for passing small distal ureteral stones in adults but not in children. Its common harms are dose-related dizziness, fatigue and postural low blood pressure, with syncope, falls and intraoperative floppy iris syndrome in cataract surgery as the notable serious ones.

Evidence grade: Disputed.

How it works

Drug class: Selective alpha-1 adrenergic receptor antagonist (quinazoline alpha-blocker)

Noradrenaline tightens smooth muscle by acting on alpha-1 receptors. Doxazosin sits on those receptors and blocks it. In the walls of arteries that means the vessels relax and blood pressure falls. In the prostate and bladder neck, where alpha-1 receptors are densely packed in the prostatic stroma, it means the muscular squeeze that narrows the urethra eases, so urine flows more freely without the prostate itself getting smaller. That is why it treats the symptoms of an enlarged prostate quickly but does nothing about the gland's size. (Source 1)

What it is used for

• In the 3,047-man MTOPS trial over a mean 4.5 years, doxazosin reduced overall clinical progression by 39% versus placebo and improved symptom scores. It did not reduce acute urinary retention or the need for invasive therapy, which finasteride and the combination did. Evidence: established. (Source 2)
• Doxazosin lowers blood pressure by about 10/8 mmHg standing, but in ALLHAT its arm was terminated early on the data review committee's recommendation: compared with chlorthalidone, heart failure was doubled and combined cardiovascular disease 25% higher, with no difference in fatal coronary disease, heart attack or total mortality. Evidence: disputed. (Source 3)
• A meta-analysis of 12 studies and 836 participants found doxazosin increased the stone expulsion rate (RR 1.64) and shortened expulsion time versus conventional care in adults with distal stones under 10 mm, with no clear difference from tamsulosin. It showed no benefit in people under 16. Evidence: limited. (Source 4)
• A 2026 review of the literature describes it as limited and heterogeneous, with randomised trials producing mixed results because of small samples and comorbidity. The review's authors call for larger trials and position psychotherapy as the better-evidenced treatment. Evidence: unknown. (Source 5)

Interactions

• Sildenafil, tadalafil, vardenafil and other PDE-5 inhibitors (label): Both lower blood pressure, and together they lower it more, which can cause dizziness or fainting. This is the interaction most likely to matter to a man taking doxazosin for prostate symptoms. (Source 6)
• Strong CYP3A inhibitors, and in theory grapefruit juice (label): Doxazosin is broken down mainly by the liver enzyme CYP3A4, so drugs that strongly block that enzyme raise doxazosin levels and the chance of low blood pressure. Grapefruit juice inhibits the same enzyme in the gut wall, so the same direction of effect is plausible for grapefruit, but the label names only strong inhibitors and no grapefruit study of doxazosin was found in the sources read here. For grapefruit this is theory. (Source 6)
• Food and meal timing (pharmacokinetic study): Taking doxazosin with food slightly reduces how high and how much drug reaches the blood, but a crossover study in twelve people found the difference too small to matter. Evening dosing gave slightly higher exposure than morning dosing in a separate crossover study. (Source 1)
• Alcohol (theoretical): No specific alcohol pharmacokinetic study of doxazosin was found in the sources read here, and the US label's interactions section names only CYP3A inhibitors and PDE-5 inhibitors. The mechanistic concern is the same one the label describes for other blood-pressure lowering combinations: alcohol causes blood vessels to dilate, which could add to doxazosin's postural blood-pressure drop and its documented potential for fainting. Treat this as theory plus a known postural-hypotension risk, not a measured interaction. (Source 6)
• Supplements marketed for prostate health, such as saw palmetto (theoretical): No pharmacokinetic or clinical interaction study between doxazosin and a specific dietary supplement was found in the sources read here. The relevant pharmacological route would be anything that inhibits CYP3A4, since that is doxazosin's main elimination pathway, or anything that lowers blood pressure further. Both are inferences from the label's own statements rather than measured interactions. (Source 6)

Stopping it

• There is no withdrawal syndrome described for doxazosin and no taper is specified. What the label does record is that the first-dose blood-pressure effect returns after a break: if the drug has been stopped for several days, it has to be restarted at the starting dose rather than the previous one. (Source 6)
• Stopping doxazosin in men on combined prostate treatment led a minority back to it. In a randomised multicentre study, 31.0% of men who stopped the alpha-blocker after two years of combination therapy resumed combination treatment within 12 months, versus 51.3% of those who stopped the 5-alpha-reductase inhibitor. (Source 7)
• Among those who did go back on it, the median time off the alpha-blocker was about five months, and the trial's overall conclusion was that stopping either drug allowed prostate disease to progress. (Source 7)
• The largest reason doxazosin has been stopped at scale was not patient tolerance but an outcome result: an independent data review committee recommended ending its ALLHAT arm after the interim comparison with chlorthalidone. (Source 3)

What goes wrong

The doxazosin arm of ALLHAT was stopped early after an interim analysis comparing it with chlorthalidone. (Source 3)

• Randomized trial, High certainty.
• Size: 24,335 patients (9,067 doxazosin, 15,268 chlorthalidone)
• Who: Patients aged 55 or over with hypertension and at least one other coronary heart disease risk factor, 625 centres in the US and Canada.
• How long: Median follow-up 3.3 years against a planned 4 to 8 years.
• Result: An independent data review committee recommended discontinuing the doxazosin arm in January 2000.
• Funding: not stated in the abstract (NIH-sponsored ALLHAT Collaborative Research Group)

In January 2000, after an interim analysis, an independent data review committee recommended discontinuing the doxazosin treatment arm based on comparisons with chlorthalidone.

Compared with chlorthalidone, doxazosin doubled the risk of heart failure in high-risk hypertensive patients. (Source 3)

• Randomized trial, High certainty.
• Size: 24,335 patients.
• Who: As above.
• How long: Median 3.3 years.
• Result: Heart failure 4-year rates 8.13% with doxazosin vs 4.45% with chlorthalidone (RR 2.04, 95% CI 1.79 to 2.32; P<.001), an absolute difference of 3.68 percentage points over four years, about one extra heart failure event for every 27 people treated for four years.
• Funding: not stated in the abstract.

Considered separately, CHF risk was doubled (4-year rates, 8.13% vs 4.45%; RR, 2.04; 95% CI, 1.79-2.32; P<.001)

Doxazosin also carried a higher risk of stroke and of combined cardiovascular disease than chlorthalidone. (Source 3)

• Randomized trial, High certainty.
• Size: 24,335 patients.
• Who: As above.
• How long: Median 3.3 years.
• Result: Stroke RR 1.19 (95% CI 1.01 to 1.40; P=.04); combined CVD 4-year rates 25.45% vs 21.76% (RR 1.25, 95% CI 1.17 to 1.33; P<.001), an absolute difference of 3.69 percentage points over four years.
• Funding: not stated in the abstract.

The doxazosin arm, compared with the chlorthalidone arm, had a higher risk of stroke (RR, 1.19; 95% CI, 1.01-1.40; P=.04) and combined CVD (4-year rates, 25.45% vs 21.76%; RR, 1.25; 95% CI, 1.17-1.33; P<.001).

The heart failure excess with doxazosin was at least as large in people with diabetes or newly found glucose disorders, despite doxazosin lowering their glucose. (Source 8)

• Randomized trial, Moderate certainty.
• Size: 8,749 with known diabetes and 1,690 with a newly diagnosed glucose disorder, within ALLHAT.
• Who: ALLHAT participants aged over 55 with hypertension and glucose disorders.
• How long: Within the ALLHAT follow-up.
• Result: Heart failure RR 1.85 (95% CI 1.56 to 2.19) in known diabetes; RR 1.63 (95% CI 1.05 to 2.55) in newly diagnosed glucose disorder, despite lower follow-up glucose on doxazosin. No difference in MI or all-cause mortality.
• Funding: not stated in the abstract.

This difference was due primarily to an increased heart failure risk in those treated with doxazosin (relative risk, 1.85; 95% confidence interval, 1.56-2.19) in the known diabetes mellitus group

In the benign prostatic hyperplasia registration trials, dizziness and fatigue were markedly more common on doxazosin than on placebo. (Source 9)

• Official position, Moderate certainty.
• Size: 665 doxazosin vs 300 placebo, within 965 BPH patients across seven placebo-controlled trials.
• Who: Patients with benign prostatic hyperplasia in seven placebo-controlled trials.
• How long: Trial durations as submitted for registration.
• Result: Dizziness 15.6% vs 9.0% placebo; fatigue 8.0% vs 1.7%; somnolence 3.0% vs 1.0%; hypotension 1.7% vs 0%; oedema 2.7% vs 0.7%; dyspnoea 2.6% vs 0.3%.
• Funding: industry data submitted for registration.

Limit of this finding: These rates are from the label's benign prostatic hyperplasia trials only, and the label reports different rates for people treated for high blood pressure. The label also contradicts itself about which table is which: the sentence introducing these figures points to 'Table 2', but the table that actually carries them is headed 'Table 1'. Read the numbers from the table that names BPH patients and the N=665 and N=300 columns, and do not rely on the label's table numbering.

NERVOUS SYSTEM DISORDERS Dizziness * 15.6% 9.0% Somnolence 3.0% 1.0%

In older women, starting an alpha-blocker was associated with more hospitalisations for low blood pressure and fainting than other blood-pressure drugs. (Source 10)

• Cohort study, Low certainty.
• Size: 14,106 women dispensed an alpha-blocker matched to 14,106 on other blood-pressure drugs, from 734,907 eligible.
• Who: Women aged 66 or over in Ontario, Canada, 1995 to 2015; mean age 75.7.
• How long: Median follow-up 1 year.
• Result: Composite of hypotension-related hospitalisation 95.7 vs 79.8 per 1,000 person-years (incident rate ratio 1.20, 95% CI 1.10 to 1.30); hypotension HR 1.71 (95% CI 1.33 to 2.20); syncope HR 1.44 (95% CI 1.18 to 1.75); no difference in falls, fractures, cardiac events or mortality.
• Funding: not stated in the abstract.

The risk was higher for hypotension (hazard ratio, 1.71; 95% CI, 1.33-2.20) and syncope (hazard ratio, 1.44; 95% CI, 1.18-1.75) with no difference in falls, fractures, adverse cardiac events, or all-cause mortality.

Alpha-blocker use was the strongest medication-related predictor of intraoperative floppy iris syndrome during cataract surgery. (Source 11)

• Cohort study, Low certainty.
• Size: 1,722 patients.
• Who: Patients aged 40 to 90 undergoing phacoemulsification cataract surgery at a tertiary centre, March 2024 to April 2025.
• How long: Prospective over the surgical episode.
• Result: Intraoperative floppy iris syndrome in 223 patients (13.0%, 95% CI 11.4 to 14.6); alpha-blocker use adjusted odds ratio 11.3 (95% CI 6.1 to 20.7)
• Funding: not stated in the abstract.

Multivariable analysis identified significant risk factors: alpha-blocker use (Adjusted odds ratio (AOR)=11.3; 95%CI: 6.1-20.7)

Hip fracture was about twice as likely in the 30 days after an alpha-blocker was dispensed to older women as in a control window. (Source 12)

• Case-control study, Very low certainty.
• Size: 287,383 subjects; 170 hip fractures in the hazard period and 79 in the control period.
• Who: Korean women prescribed an alpha-blocker for voiding dysfunction, 2008 to 2012; mean age 65.1.
• How long: 30-day hazard period after dispensing versus a 30-day control period 360 days earlier.
• Result: Hip fractures 763.4 vs 348.5 per 100,000 person-years; hazard ratio 2.19 (95% CI 1.74 to 2.77)
• Funding: not stated in the abstract.

The hazard ratio for hip fracture after use of an alpha blocker was 2.19 (95% confidence interval, 1.74-2.77).

The label records a risk of fainting, especially after the first dose or a dose increase, which is why blood pressure is monitored for six hours after each step up. (Source 6)

• Official position, Moderate certainty.
• Size: Not quantified.
• Who: Anyone starting or increasing doxazosin.
• How long: Mainly within hours of a dose, though symptomatic postural hypotension has been reported later.
• Result: Potential for syncope, especially after the initial dose or a dose increase; additive hypotension with PDE-5 inhibitors; intraoperative floppy iris syndrome in cataract surgery.
• Funding: regulatory position.

As with other alpha-blockers, there is a potential for syncope, especially after the initial dose or after an increase in dosage strength.

What the evidence supports

Doxazosin reduced the risk of overall clinical progression of benign prostatic hyperplasia by 39% over a mean 4.5 years. (Source 2)

• Randomized trial, High certainty.
• Size: 3,047 men across four arms (placebo, doxazosin, finasteride, combination)
• Who: Men with benign prostatic hyperplasia.
• How long: Mean follow-up 4.5 years.
• Result: 39% risk reduction in overall clinical progression (P<0.001) versus placebo; combination therapy 66% (P<0.001). Significant symptom-score improvement (P<0.001)
• Funding: not stated in the abstract.

was significantly reduced by doxazosin (39 percent risk reduction, P<0.001) and finasteride (34 percent risk reduction, P=0.002), as compared with placebo

Doxazosin increased the rate at which small stones in the lower ureter passed in adults, pooled across 12 studies. (Source 4)

• Meta-analysis, Low certainty.
• Size: 12 studies, 836 participants.
• Who: People with distal ureteral stones smaller than 10 mm.
• How long: Varied by study.
• Result: Stone expulsion rate RR 1.64 (95% CI 1.32 to 2.04, P<0.00001) versus conventional care; expulsion time WMD -3.97 days (95% CI -5.68 to -2.27). No significant difference from tamsulosin.
• Funding: not stated in the abstract.

The present meta-analysis showed doxazosin could significantly increase SER [RR=1.64,95%CI (1.32, 2.04), P < 0.00001]

What the evidence does not support

Doxazosin did not reduce acute urinary retention or the need for invasive prostate treatment, although finasteride and the combination did. (Source 2)

• Randomized trial, High certainty.
• Size: 3,047 men.
• Who: Men with benign prostatic hyperplasia.
• How long: Mean follow-up 4.5 years.
• Result: Acute urinary retention and need for invasive therapy significantly reduced by combination therapy (P<0.001) and finasteride (P<0.001) but not by doxazosin.
• Funding: not stated in the abstract.

The risks of acute urinary retention and the need for invasive therapy were significantly reduced by combination therapy (P<0.001) and finasteride (P<0.001) but not by doxazosin.

In the same meta-analysis, doxazosin showed no benefit for stone passage in people under 16. (Source 4)

• Meta-analysis, Very low certainty.
• Size: Children subgroup within 12 studies and 836 participants.
• Who: People under 16 with distal ureteral stones under 10 mm.
• How long: Varied by study.
• Result: Stone expulsion rate RR 1.63 (95% CI 0.73 to 3.64), P = 0.23.
• Funding: not stated in the abstract.

In the subgroup analyses, doxazosin showed no benefit in the children subgroup (<16 years old) [RR=1.63,95% CI (0.73,3.64), P =0.23].

Where the evidence is mixed

The excess cardiovascular risk was not seen for heart attack or death: those outcomes did not differ between doxazosin and chlorthalidone. (Source 3)

• Randomized trial, High certainty.
• Size: 24,335 patients; 365 events in the doxazosin arm and 608 in the chlorthalidone arm.
• Who: As above.
• How long: Median 3.3 years.
• Result: Fatal coronary heart disease or non-fatal MI RR 1.03 (95% CI 0.90 to 1.17; P=.71); total mortality 4-year rates 9.62% vs 9.08% (RR 1.03, 95% CI 0.90 to 1.15; P=.56)
• Funding: not stated in the abstract.

Total mortality did not differ between the doxazosin and chlorthalidone arms (4-year rates, 9.62% and 9.08%, respectively; RR, 1.03; 95% CI, 0.90-1.15; P=.56.)

For trauma-related nightmares in PTSD, randomised trials of doxazosin have given mixed results and the evidence base is small. (Source 5)

• Expert review, not systematic, Very low certainty.
• Size: Not pooled; the review describes the literature as limited and heterogeneous.
• Who: Adults with PTSD and trauma-related nightmares, some with alcohol-related comorbidity.
• How long: Varied by study.
• Result: No pooled effect estimate given; the review reports possible reductions in nightmare frequency and intensity but mixed randomised results.
• Funding: not stated in the abstract.

However, randomized controlled trials have produced mixed results due to small sample sizes, population heterogeneity, and comorbidities such as alcohol-related disorders.

Where the research disagrees

Whether doxazosin is an acceptable blood-pressure drug, given that it lowers blood pressure but did worse than a diuretic on cardiovascular outcomes

• ALLHAT Collaborative Research Group (2000), Randomised, double-blind, active-controlled trial, 24,335 patients, median 3.3 years: "Considered separately, CHF risk was doubled (4-year rates, 8.13% vs 4.45%; RR, 2.04; 95% CI, 1.79-2.32; P<.001)" and the arm was terminated early (Source 3)
• US prescribing information for CARDURA (DailyMed, 2023), Regulatory position based on blood pressure as the endpoint rather than cardiovascular events: "CARDURA is indicated for the treatment of hypertension, to lower blood pressure." The label retains the indication and documents a blood-pressure reduction of about 10/8 mmHg standing (Source 6)

Whether the heart failure signal in ALLHAT was real or an artefact of how heart failure was diagnosed

• ALLHAT investigators reporting the heart failure validation exercise (2002), Post-hoc central validation of adjudicated heart failure events within the randomised trial: "Results of the validation process supported findings of increased heart failure in the ALLHAT doxazosin treatment arm compared to the chlorthalidone treatment arm." (Source 13)
• ALLHAT glucose-disorder subgroup report (2004), Pre-specified subgroup analysis of the randomised trial in 8,749 people with diabetes and 1,690 with newly diagnosed glucose disorder: "treatment with doxazosin increases the risk of combined cardiovascular disease and heart failure despite lower glucose levels" (Source 8)

How much

• Reference intake: There is no reference intake for a prescription medicine. Dosing is set by the prescriber. The US label (CARDURA, DailyMed, 2023) starts at 1 mg once daily for both uses and titrates at one- to two-week intervals, with blood pressure monitored for at least six hours after the first dose and each increase. (Source 6)
• Upper limit: The US label (2023) gives a maximum of 8 mg once daily for benign prostatic hyperplasia and up to 16 mg once daily for hypertension. ALLHAT used 2 to 8 mg a day and still found a doubling of heart failure versus chlorthalidone, so the label maximum is not a safety threshold for cardiovascular outcomes. (Source 6)
• Studied: ALLHAT randomised 9,067 participants to doxazosin 2 to 8 mg a day against chlorthalidone 12.5 to 25 mg a day, for a planned 4 to 8 years. (Source 3)
• Studied: MTOPS compared placebo, doxazosin, finasteride and the combination in 3,047 men over a mean 4.5 years. (Source 2)
• Studied: The label's pooled hypertension analysis used 1 to 16 mg once daily in about 300 patients per group. (Source 1)
• Studied: The stone-expulsion meta-analysis pooled 12 studies of doxazosin versus conventional care or tamsulosin in 836 people with distal stones under 10 mm. (Source 4)

A common belief, and what the research shows

The belief: A drug that lowers blood pressure must reduce heart attacks and strokes, so any blood-pressure pill is as good as another.

What the research shows: Doxazosin is the clearest counter-example in the hypertension literature. It does lower blood pressure, by "about 10/8 mmHg compared to placebo in the standing position", and yet when tested head to head against a cheap diuretic in 24,335 high-risk patients, "The doxazosin arm, compared with the chlorthalidone arm, had a higher risk of stroke (RR, 1.19; 95% CI, 1.01-1.40; P=.04) and combined CVD (4-year rates, 25.45% vs 21.76%; RR, 1.25; 95% CI, 1.17-1.33; P<.001)." The arm was stopped early. Blood pressure is a surrogate; outcome trials are what settle the question. A second misconception runs the other way: ALLHAT did not show doxazosin kills people, because "Total mortality did not differ between the doxazosin and chlorthalidone arms (4-year rates, 9.62% and 9.08%, respectively; RR, 1.03; 95% CI, 0.90-1.15; P=.56.)"

Questions and answers

What is it?

Doxazosin is a prescription tablet, not a nutrient, taken once a day. It belongs to the alpha-blocker family and is approved both for the urinary symptoms of an enlarged prostate and for high blood pressure. It stays in the body a long time, with an elimination half-life of about 22 hours, which is why one daily dose works. (Source 6)

What does it do in the body?

Noradrenaline normally tightens smooth muscle by acting on alpha-1 receptors. Doxazosin blocks those receptors. In blood vessels this lets them relax, so blood pressure falls. In the prostate and bladder neck, where alpha-1 receptors are densely packed, it relaxes the muscular squeeze that narrows the urethra, so urine flows more easily. It does not shrink the prostate, which is why it eases symptoms quickly but does not change the gland itself. (Source 1)

Is it good or bad for you?

It depends which problem it is being used for. For prostate symptoms the long-term randomised evidence is good: a 39% reduction in clinical progression over a mean 4.5 years in 3,047 men. For high blood pressure the same drug looked worse than a cheap diuretic when tested on outcomes rather than blood pressure numbers, with heart failure doubled and the trial arm stopped early. Its everyday harms are dizziness in about one in six and fatigue in about one in twelve, both more than placebo, plus a risk of fainting after the first dose or a dose increase. (Source 3)

How do you get more of it?

Doxazosin is prescription-only and there is no food or supplement source. Trials have used 1 to 16 mg once daily: ALLHAT used 2 to 8 mg a day in 9,067 people, MTOPS titrated it in men with prostate disease, and the stone-passage studies typically used 4 to 8 mg a day. The label starts everyone at 1 mg once daily and titrates upward at one- to two-week intervals. None of that is advice aimed at any reader. (Source 6)

If it is harmful, what reduces it?

Doxazosin is cleared by the liver, mainly through the CYP3A4 enzyme, with an elimination half-life of about 22 hours, so it takes several days to leave the body completely after the last dose. There is no antidote and no taper schedule. Because the first-dose blood-pressure effect returns, the label requires restarting at the initial dose after a break of several days rather than resuming the old dose. (Source 6)

Why might someone be low in it or missing it?

Nobody is deficient in doxazosin; the body does not make it. Reasons someone who might benefit is not on it include the ALLHAT result steering prescribers towards diuretics and other classes for blood pressure, intolerance of dizziness, fatigue or postural symptoms, which caused discontinuation in about 2% in the hypertension trials, and the risk of complications during cataract surgery. Effects also fade if doses are missed, because the postural blood-pressure effect resets after a break. (Source 14)

Which whole foods contain it or feed it?

No whole food contains doxazosin. Food matters only in that taking the tablet with a meal slightly lowers peak blood levels, by 18%, and total exposure by 12%, which the label judges not clinically significant. Grapefruit juice inhibits CYP3A4, the enzyme that clears doxazosin, so in theory it could raise levels, but no grapefruit study of doxazosin was found in the sources read here. (Source 1)

What happens if you do not have it?

Without an alpha-blocker, men with benign prostatic hyperplasia have more clinical progression: in MTOPS, the placebo group's risk of progression was 39% higher than the doxazosin group's. In the randomised discontinuation study, stopping the alpha-blocker after two years of combination therapy led 31.0% of men back onto combination treatment within a year, and the authors concluded prostate disease progressed after stopping either drug. For high blood pressure, the ALLHAT comparison suggests nothing is lost and possibly something gained by using a diuretic instead. (Source 7)

How can you test for it?

There is no blood test for doxazosin levels in routine care. What is monitored is the effect: the label requires blood pressure to be measured for at least six hours after the first dose and after each increase, because that is when postural hypotension and fainting are most likely, and routine blood-pressure monitoring in men taking it for prostate symptoms. Prostate symptom scores and urinary flow rate are the measures used in trials to judge benefit. Before cataract surgery, telling the surgeon about current or past alpha-blocker use matters more than any test, because alpha-blocker exposure raised the odds of intraoperative floppy iris syndrome more than eleven-fold in one prospective cohort. (Source 6)

References

1. DailyMed, U.S. National Library of Medicine (Viatris Specialty LLC). CARDURA (doxazosin) tablets: mechanism of action, pharmacokinetics and clinical studies. 2023. Read the source
2. The New England Journal of Medicine (abstract read via Europe PMC REST). The long-term effect of doxazosin, finasteride, and combination therapy on the clinical progression of benign prostatic hyperplasia. 2003. PMID 14681504, DOI 10.1056/NEJMoa030656. Read the source
3. JAMA (abstract read via Europe PMC REST). Major cardiovascular events in hypertensive patients randomized to doxazosin vs chlorthalidone: the antihypertensive and lipid-lowering treatment to prevent heart attack trial (ALLHAT). 2000. PMID 10789664. Read the source
4. Urology Journal (abstract read via Europe PMC REST). Efficacy and Safety of Doxazosin in Medical Expulsive Therapy for Distal Ureteral Stones: A Systematic Review and Meta-analysis. 2020. PMID 32869260, DOI 10.22037/uj.v16i7.5958. Read the source
5. L'Encephale (abstract read via Europe PMC REST). Management of trauma-related nightmares in PTSD: Can doxazosin serve as a pragmatic alternative to prazosin?. 2026. PMID 41839711, DOI 10.1016/j.encep.2026.01.004. Read the source
6. DailyMed, U.S. National Library of Medicine (Viatris Specialty LLC). CARDURA (doxazosin) tablets: indications, dosage, warnings, mechanism and drug interactions. 2023. Read the source
7. Urology (abstract read via Europe PMC REST). Progression of lower urinary tract symptoms after discontinuation of 1 medication from 2-year combined alpha-blocker and 5-alpha-reductase inhibitor therapy for benign prostatic hyperplasia in men--a randomized multicenter study. 2014. PMID 24332123, DOI 10.1016/j.urology.2013.09.036. Read the source
8. Journal of Clinical Hypertension (abstract read via Europe PMC REST). Cardiovascular outcomes using doxazosin vs. chlorthalidone for the treatment of hypertension in older adults with and without glucose disorders: a report from the ALLHAT study. 2004. PMID 15010644, DOI 10.1111/j.1524-6175.2004.03216.x. Read the source
9. DailyMed, U.S. National Library of Medicine (Viatris Specialty LLC). CARDURA (doxazosin) tablets: ADVERSE REACTIONS, Clinical Trials Experience - Benign Prostatic Hyperplasia (BPH). 2023. Read the source
10. Hypertension (abstract read via Europe PMC REST). Alpha-Blocker Use and the Risk of Hypotension and Hypotension-Related Clinical Events in Women of Advanced Age. 2019. PMID 31327266, DOI 10.1161/HYPERTENSIONAHA.119.13289. Read the source
11. International Ophthalmology (abstract read via Europe PMC REST). Intraoperative floppy iris syndrome in cataract surgery: effects of opium use. 2026. PMID 42627429, DOI 10.1007/s10792-026-04174-9. Read the source
12. Lower Urinary Tract Symptoms (abstract read via Europe PMC REST). Risk for Hip Fracture due to Alpha Blocker Treatment in Korean Women: National Health Insurance Database Study. 2018. PMID 27990752, DOI 10.1111/luts.12157. Read the source
13. Current Controlled Trials in Cardiovascular Medicine (abstract read via Europe PMC REST). Validation of Heart Failure Events in the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) Participants Assigned to Doxazosin and Chlorthalidone. 2002. PMID 12459039, DOI 10.1186/1468-6708-3-10. Read the source
14. DailyMed, U.S. National Library of Medicine (Viatris Specialty LLC). CARDURA (doxazosin) tablets: ADVERSE REACTIONS, Clinical Trials Experience - Hypertension. 2023. Read the source