Long-acting selective α1-adrenoceptor antagonist
ATC code: C02CA04 (Doxazosin)
A selective postsynaptic α1-adrenoceptor antagonist in vascular smooth muscle, prostate, and bladder neck. Reduces peripheral vascular resistance and BP; relaxes prostatic smooth muscle and improves micturition. Less prostate-selective than tamsulosin and silodosin – more orthostatic hypotension. Half-life 22 hours in extended-release GITS form (Cardura XL) – once-daily dosing.
First line
First-line for symptomatic benign prostatic hyperplasia per EAU 2024 alongside tamsulosin, silodosin, and alfuzosin. Dose 4–8 mg once daily (GITS form). Effective on IPSS and Qmax. In patients with concomitant hypertension, adds antihypertensive effect.
Second line
In hypertension, α-blockers are no longer universal first-line per 2024 after ALLHAT (2000) showed doxazosin inferior to chlorthalidone on heart failure. Used as a fourth drug in resistant hypertension or with concomitant BPH. Dose 4–8 mg once daily.
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
Not recommended
Doxazosin is an alpha-1 blocker used for hypertension (as a non-first-line drug; the ALLHAT 2000 trial showed it underperforms diuretics on hard endpoints) and for benign prostatic hyperplasia. For post-traumatic stress disorder with nightmares, prazosin (a related drug) is used off-label ( 2017 and VA/DoD 2023 guidelines). Doxazosin is not included in that recommendation and is not used for anxiety control outside HTN, BPH, or PTSD. The drug has serious risks: a first-dose phenomenon with severe orthostatic hypotension and syncope (especially in older adults), paradoxical rebound hypertension on abrupt discontinuation, and fall risk. If doxazosin was prescribed for anxiety or nightmares, consider seeking a second opinion.
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Limited data. For pregnancy hypertension, labetalol or methyldopa are preferred.
Not used during lactation.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Doxazosin is evaluated for the following indications with varying evidence strength: Benign prostatic hyperplasia (evidence tier A), Hypertension (evidence tier C), Stress and anxiety (evidence tier F). See the full indication matrix with dosing and citations above on this page.
Common side effects of Doxazosin (≥ 1 in 100): Dizziness, Orthostatic hypotension, Nasal congestion, Fatigue, Ankle edema, Retrograde ejaculation. See the Safety section for uncommon and serious reactions.
FDA category C. Limited data. For pregnancy hypertension, labetalol or methyldopa are preferred.
Not used during lactation.
Doxazosin is contraindicated in: Doxazosin or quinazoline hypersensitivity; Hypotension; Severe hepatic impairment; Pregnancy and lactation; Age under 18. Full list in the Safety section.