Doxazosin: uses, dosing, side effects & brands

Doxazosin is an alpha-adrenergic blocker sold in the U.S. under 3 brand and generic names, for hypertension, prostatic hyperplasia and urinary retention. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.

By the pharmaranks editorial teamReviewed against the FDA (openFDA label, NDC Directory & Enforcement) sourcesUpdated Jul 24, 2026How we research

Key facts

Drug class: Alpha-Adrenergic Blocker
Treats (across its forms): Hypertension, Prostatic Hyperplasia and Urinary Retention
Available as: Tablet · Tablet, extended release
Sold as: 3 products — Cardura, Cardura XL and Doxazosin Mesylate
Prescription?: Prescription only
Generic available?: Yes
Half-life: about 22 hours (terminal/beta phase)
What the pharmacy pays: about $3 for a 30-count supply — not your price

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How Cardura is dosed

From the FDA label for Cardura (application NDA019668). Other doxazosin products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.

For the treatment of BPH: Initiate therapy at 1 mg once daily. Dose may be titrated at 1 to 2-week intervals, up to 8 mg once daily. ( 2.2 ) • For the treatment of hypertension: Initiate therapy at 1 mg once daily. Dose may be titrated as needed, up to 16 mg once daily. ( 2.3 ) 2.1 Dosing Information Following the initial dose and with each dose increase of Doxazosin, monitor blood pressure for at least 6 hours following administration. If Doxazosin tablet administration is discontinued for several days, therapy should be restarted using the initial dosing regimen. 2.2 Benign Prostatic Hyperplasia The recommended initial dosage of Doxazosin tablet is 1 mg given once daily either in the morning or evening. Depending on the individual patient’s urodynamics and BPH symptomatology, the dose may be titrated at 1 to 2 week intervals to 2 mg, and thereafter to 4 mg and 8 mg once daily. The maximum recommended dose for BPH is 8 mg once daily. Routinely monitor blood pressure in these patients. 2.3 Hypertension The initial dosage of Doxazosin tablet is 1 mg given once daily. Daily dosage may be doubled up 16 mg once daily, as needed, to achieve the desired reduction in blood pressure.

Everything below is the FDA label for Cardura (tablet). Doxazosin is also sold as tablet, extended release, and those are different medicines to take — follow the label for the one you were prescribed.

Cardura side effects

The most commonly reported adverse reactions from clinical trials are fatigue, malaise, hypotension, and dizziness. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Viatris at 1-877-446-3679 (1-877-4-INFO-RX) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Benign Prostatic Hyperplasia (BPH) The incidence of adverse events has been ascertained from worldwide clinical trials in 965 BPH patients. The incidence rates presented below (Table 2) are based on combined data from seven placebo‑controlled trials involving once-daily administration of Doxazosin tablet in doses of 1 to 16 mg in hypertensives and 0.5 to 8 mg in normotensives. Adverse reactions occurring more than 1% more frequently in BPH patients treated with Doxazosin vs. placebo are summarized in Table 1. Table 1. Adverse Reactions Occurring More than 1% More Frequently in BPH Patients Treated with Doxazosin Versus Placebo BODY SYSTEM Doxazosin N=665 Placebo N=300 NERVOUS SYSTEM DISORDERS Dizziness Includes vertigo 15.6% 9.0% Somnolence 3.0% 1.0% CARDIAC DISORDERS Hypotension 1.7% 0% RESPIRATORY, THORACIC AND MEDIASTINAL…

Who shouldn’t take Cardura

The use of Doxazosin tablet is contraindicated in patients with a hypersensitivity to doxazosin, other quinazolines (e.g., prazosin, terazosin), or any of its components. • Hypersensitivity to doxazosin, other quinazolines, or any other ingredient in Doxazosin. ( 4 )

Cardura drug interactions

Strong cytochrome P450 (CYP) 3A inhibitors may increase exposure to doxazosin and increased risk of hypotension. ( 7.1 ) • Concomitant administration of Doxazosin with a phosphodiesterase-5 (PDE-5) inhibitor can result in additive blood pressure lowering effects and symptomatic hypotension. ( 7.2 ) 7.1 CYP 3A Inhibitors In vitro studies suggest that doxazosin is a substrate of CYP 3A4. Strong CYP3A inhibitors may increase exposure to doxazosin. Monitor blood pressure and for symptoms of hypotension when Doxazosin is used concomitantly with strong CYP3A inhibitors [see Clinical Pharmacology (12.3) ]. 7.2 Phosphodiesterase-5 (PDE-5) Inhibitors Concomitant administration of Doxazosin with a phosphodiesterase-5 (PDE-5) inhibitor can result in additive blood pressure lowering effects and symptomatic hypotension. Monitor blood pressure and for symptoms of hypotension [see Warnings and Precautions (5.1) ]. Drug Interactions There are only limited data on the effects of drugs known to influence the hepatic metabolism of doxazosin (e.g., cimetidine). Cimetidine: In healthy volunteers, the administration of a single 1 mg dose of doxazosin on day 1 of a four-day regimen of oral cimetidine (400 mg twice daily) resulted in a 10% increase in mean AUC of doxazosin, and a slight but not significant increase in mean C max and mean half-life of doxazosin. In vitro data in human plasma indicate that Doxazosin has no effect on protein binding of digoxin, warfarin, phenytoin, or indomethacin.

Every doxazosin product we track (3)

Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.

Doxazosin products
#	Drug	Rating	Type	Form	Generic?	Pharmacy pays
1	Cardura	70/100	Prescription	Tablet	Generic	$3	View →
2	Cardura XL	68/100	Prescription	Tablet	Generic	$3	View →
3	Doxazosin Mesylate	Not yet rated	Prescription	Tablet	Generic	$3	View →

What doxazosin pills look like

Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.

Doxazosin pill imprints
Imprint	Strength	Colour	Shape	Maker
AC;358	4 mg	white	round	—
596;TV	4 mg	white	diamond	—
593;TV	2 mg	white	oval	—
AC;358	4 mg	white	round	—
Cardura;1;mg	1 mg	white	oval	—
Cardura;2;mg	2 mg	yellow	oval	—
Cardura;4;mg	4 mg	orange	oval	—
Cardura;8;mg	8 mg	green	oval	—
CN1;Pfizer	1 mg	white	round	—
CN2;Pfizer	2 mg	white	oval	—
CN4;Pfizer	4 mg	white	diamond	—
CN8;Pfizer	8 mg	white	oval	—

Doxazosin recalls

From the FDA Enforcement database. A recall covers specific lots — not the drug as a whole.

Can you crush or split doxazosin?

At least one doxazosinproduct is labelled to be swallowed whole — crushing an extended-release tablet releases the whole day’s dose at once. Which applies depends on the form you were given.

What each doxazosin label says about crushing, splitting and chewing

How long doxazosin keeps

No doxazosin label we read sets a separate limit for after opening, but they do specify how it must be stored — and the stability behind any date assumes those conditions.

Does doxazosin expire? The in-use limits and storage rules from its labels

Doxazosin and breastfeeding

From LactMed, the US National Library of Medicine’s Drugs and Lactation Database — quoted, not rewritten.

Limited information indicates that maternal doses of 4 mg daily produce low very levels in milk and would not be expected to cause any adverse effects in breastfed infants.

Full LactMed record for doxazosin: levels in milk, effects in breastfed infants, and the drugs it would consider instead

National Institute of Child Health and Human Development, record revised December 15, 2024. LactMed states its information is not a substitute for professional judgement.

What people report to the FDA about doxazosin

The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 7,989 reports naming doxazosin, and the FDA flagged 80% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:

dyspnoea538 reports
fatigue444 reports
diarrhoea411 reports
dizziness381 reports
asthma348 reports
nausea305 reports
hypotension304 reports
asthenia297 reports

Read these as a signal, not a rate. A report does not mean doxazosin caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.

Source: openFDA drug/event (FAERS), retrieved August 25, 2026.

How long doxazosin stays in your system

The elimination half-life of doxazosin is about 22 hours (terminal/beta phase). The label states plasma elimination is biphasic and reports the terminal (beta) elimination half-life of about 22 hours — not the distribution phase. The parent compound doxazosin is primarily responsible for the drug's activity; several active metabolites exist but circulate at low concentrations and their pharmacokinetics have not been characterized, so no active metabolite is reported to outlast the parent. Populations: half-life is unchanged in older adults (65+ vs under 65 are similar) and in renal impairment (no significant alterations). Hepatic impairment: mild cirrhosis (Child-Pugh A) raises doxazosin exposure ~40%; the effect of moderate-to-severe (Child-Pugh B/C) impairment is not known.

Doxazosin label — DailyMed (Clinical Pharmacology 12.3, Excretion) ↗

Half-life is how long the body takes to clear half a dose. It is not the same as how long a drug test can detect it, and it varies with age, kidney and liver function.

Related calculators

How long it stays in your system →

Frequently asked questions

What is Cardura?

Doxazosin is a quinazoline compound that is a selective inhibitor of the alpha 1 subtype of alpha-adrenergic receptors.

What kind of drug is doxazosin?

The FDA classifies doxazosin as an alpha-adrenergic blocker. Alpha-adrenergic blockers block the alpha-1 receptors that adrenaline-like signals use to tighten muscle in blood vessels and the prostate. This relaxes those muscles, lowering blood pressure and easing urine flow in men with an enlarged prostate. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.

How long does doxazosin stay in your system?

The elimination half-life of doxazosin is about 22 hours (terminal/beta phase) — that is how long the body takes to clear half of a dose. The label states plasma elimination is biphasic and reports the terminal (beta) elimination half-life of about 22 hours — not the distribution phase. The parent compound doxazosin is primarily responsible for the drug's activity; several active metabolites exist but circulate at low concentrations and their pharmacokinetics have not been characterized, so no active metabolite is reported to outlast the parent. Populations: half-life is unchanged in older adults (65+ vs under 65 are similar) and in renal impairment (no significant alterations). Hepatic impairment: mild cirrhosis (Child-Pugh A) raises doxazosin exposure ~40%; the effect of moderate-to-severe (Child-Pugh B/C) impairment is not known. Half-life is not the same as how long a drug test can detect the drug, and it varies with age, kidney and liver function.

Can you take doxazosin with other medicines?

It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run doxazosin against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.

What brand names is doxazosin sold under?

We track 3 doxazosin-containing products in the U.S.: Cardura, Cardura XL and Doxazosin Mesylate. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.

What forms does doxazosin come in?

Across the brands we track, doxazosin is currently marketed as tablet and tablet, extended release, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.

Is there a generic doxazosin?

Yes. Our catalog lists 1 generic doxazosin product alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.

Has doxazosin been recalled?

The FDA's Enforcement database lists at least 5 recall records whose product description mentions doxazosin. The most recent: Doxazosin Tablets (Jan 21, 2026). A recall applies to specific lots, not to the drug as a whole — check the record for the affected lot numbers.

Cite this page

APA: pharmaranks. (2026, July 24). Doxazosin: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/doxazosin
MLA: “Doxazosin: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/doxazosin.

We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.

Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.

Read the full FDA label for doxazosin on DailyMed (NIH) ↗.