Clinical data
dok-SAY-zə-sin OR
Trade namesCardura, Carduran, others
License data
Routes of
By mouth
ATC code
Legal status
Legal status
Pharmacokinetic data
Protein binding98%
Elimination half-life22 hours
  • (RS)-2-[4-(2,3-Dihydro-1,4-benzodioxine-2-carbonyl)piperazin-1-yl]-6,7-dimethoxyquinazolin-4-amine
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.128.642 Edit this at Wikidata
Chemical and physical data
Molar mass451.483 g·mol−1
3D model (JSmol)
ChiralityRacemic mixture
  • O=C(N3CCN(c2nc1cc(OC)c(OC)cc1c(n2)N)CC3)C4Oc5c(OC4)cccc5
  • InChI=1S/C23H25N5O5/c1-30-18-11-14-15(12-19(18)31-2)25-23(26-21(14)24)28-9-7-27(8-10-28)22(29)20-13-32-16-5-3-4-6-17(16)33-20/h3-6,11-12,20H,7-10,13H2,1-2H3,(H2,24,25,26) checkY

Doxazosin, sold under the brand names Cardura among others, is a medication used to treat symptoms of benign prostatic hyperplasia (enlarged prostate), hypertension (high blood pressure), and posttraumatic stress disorder (PTSD).[1][2] For high blood pressure, it is a less preferred option.[2] It is taken by mouth.[2]

Common side effects include dizziness, sleepiness, swelling, nausea, shortness of breath, and abdominal pain.[2] Severe side effects may include low blood pressure with standing, an irregular heart beat, and priapism.[2][3] It is a α1-selective adrenergic blocker in the quinazoline class of compounds.[2]

Doxazosin was patented in 1977 and came into medical use in 1988.[4] It is available as a generic medication.[3] In 2021, it was the 195th most commonly prescribed medication in the United States, with more than 2 million prescriptions.[5][6]

A 2021 study associated doxazosin with decelerated biological aging in humans and confirmed its causal role in longevity in C. elegans.[7]

Medical uses

High blood pressure

Doxazosin is usually added to other antihypertensive therapy such as calcium channel antagonists, diuretics, beta-adrenoreceptor antagonists, angiotensin-converting enzyme inhibitors and angiotensin-2 receptor blockers.[8]

Doxazosin is generally considered to be safe, well tolerated and effective as an add-on (adjunctive) antihypertensive drug.[9]

Like other alpha-1 receptor antagonists, it has a role in the peri-operative management of pheochromocytoma.[10]

Benign prostatic hyperplasia

Doxazosin is considered to be effective in reducing urinary symptom scores and improving peak urinary flow in men with benign prostatic hypertrophy.[11] The bladder neck is densely packed with alpha-1 receptors.

PTSD nightmares and flashbacks

Sympatholytic drugs, including prazosin and doxazosin, are used for nightmares and flashbacks in posttraumatic stress disorder (PTSD). Doxazosin is very well tolerated for this constellation of symptoms. Given its long half-life, doxazosin lasts much longer than prazosin. While prazosin is dosed up to 4 times daily, doxazosin is generally dosed only once daily (at night). Both are alpha-1 antagonists. Other sympatholytic drugs include clonidine and guanfacine, which are alpha-2 agonists; they are not in the same exact class as doxazosin and prazosin.


The Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) study stopped its arm of the trial looking at alpha blockers, because doxazosin was less effective than a simple diuretic, and because patients on doxazosin had a 25% higher rate of cardiovascular disease and twice the rate of congestive heart failure as patients on diuretics.[12] Pfizer, aware of the results before publication, launched a marketing campaign in early 2000, and sales were largely unaffected, despite the dangers highlighted by the study.[13][14]


  1. ^ a b "Cardura- doxazosin mesylate tablet". DailyMed. Retrieved 18 June 2021.
  2. ^ a b c d e f "Doxazosin Mesylate Monograph for Professionals". American Society of Health-System Pharmacists. Retrieved 17 March 2019.
  3. ^ a b British national formulary : BNF 76 (76 ed.). Pharmaceutical Press. 2018. p. 765. ISBN 9780857113382.
  4. ^ Fischer J, Ganellin CR (2006). Analogue-based Drug Discovery. John Wiley & Sons. p. 455. ISBN 9783527607495.
  5. ^ "The Top 300 of 2021". ClinCalc. Archived from the original on 15 January 2024. Retrieved 14 January 2024.
  6. ^ "Doxazosin - Drug Usage Statistics". ClinCalc. Retrieved 14 January 2024.
  7. ^ McIntyre RL, Rahman M, Vanapalli SA, Houtkooper RH, Janssens GE (2021). "Biological Age Prediction From Wearable Device Movement Data Identifies Nutritional and Pharmacological Interventions for Healthy Aging". Frontiers in Aging. 2: 708680. doi:10.3389/fragi.2021.708680. PMC 9261299. PMID 35822021.
  8. ^ Wykretowicz A, Guzik P, Wysocki H (March 2008). "Doxazosin in the current treatment of hypertension". Expert Opinion on Pharmacotherapy. 9 (4): 625–633. doi:10.1517/14656566.9.4.625. PMID 18312163. S2CID 42056694.
  9. ^ Chapman N, Chen CY, Fujita T, Hobbs FD, Kim SJ, Staessen JA, et al. (September 2010). "Time to re-appraise the role of alpha-1 adrenoceptor antagonists in the management of hypertension?". Journal of Hypertension. 28 (9): 1796–1803. doi:10.1097/HJH.0b013e32833b912c. PMID 20543713. S2CID 31819062.
  10. ^ Mazza A, Armigliato M, Marzola MC, Schiavon L, Montemurro D, Vescovo G, et al. (April 2014). "Anti-hypertensive treatment in pheochromocytoma and paraganglioma: current management and therapeutic features". Endocrine. 45 (3): 469–478. doi:10.1007/s12020-013-0007-y. PMID 23817839. S2CID 25504151.
  11. ^ Yuan J, Liu Y, Yang Z, Qin X, Yang K, Mao C (March 2013). "The efficacy and safety of alpha-1 blockers for benign prostatic hyperplasia: an overview of 15 systematic reviews". Current Medical Research and Opinion. 29 (3): 279–287. doi:10.1185/03007995.2013.766594. PMID 23323875. S2CID 26341029.
  12. ^ Piller LB, Davis BR, Cutler JA, Cushman WC, Wright JT, Williamson JD, et al. (November 2002). "Validation of Heart Failure Events in the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) Participants Assigned to Doxazosin and Chlorthalidone". Current Controlled Trials in Cardiovascular Medicine. 3 (1): 10. doi:10.1186/1468-6708-3-10. PMC 149403. PMID 12459039.
  13. ^ Goldacre, Ben (2012) Bad Pharma How drug companies mislead doctors and harm patients, Fourth Estate, ISBN 0007350740.
  14. ^ Lenzer J (18 January 2003). "Spin doctors soft pedal data on antihypertensives". BMJ. 326 (7381): 170. doi:10.1136/bmj.326.7381.170. PMC 1128917.