What the label lists and what reports show
Doxazosin side effects
Doxazosin's FDA label: “The most commonly reported adverse reactions from clinical trials are fatigue, malaise, hypotension, and dizziness.” FAERS holds 35,891 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is dyspnoea (1,985 reports).
- Generic listed
Check it at the source: the doxazosin FDA label on DailyMed (effective October 15, 2023, Viatris Specialty LLC); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of CARDURA?CARDURA may cause serious side effects, including: • A sudden drop in blood pressure, especially when you first start treatment or when there is an increase in your dose of CARDURA, is common but can also be serious. This may cause you to faint, or to feel dizzy or lightheaded. Your risk of having this problem may be increased if you take CARDURA with certain other medicines that lower blood pressure including PDE-5 inhibitors. Your healthcare provider may monitor your blood pressure while you take CARDURA. See “What should I avoid while taking CARDURA?”. • Eye problems during cataract surgery. A condition called Intraoperative Floppy Iris Syndrome (IFIS) can happen during cataract surgery if you take or have taken alpha-blockers such as CARDURA. If you need to have cataract surgery, be sure to tell your healthcare provider if you take or have taken CARDURA. […]
Source: FDA drug label, Viatris Specialty LLC, effective October 15, 2023 (SPL set 5e1f5e49-2da1-43ab-9795-228a8bcc5a82), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most commonly reported adverse reactions from clinical trials are fatigue, malaise, hypotension, and dizziness.
Table 1. Adverse Reactions Occurring More than 1% More Frequently in BPH Patients Treated with CARDURA Versus Placebo
| BODY SYSTEM | CARDURA N=665 | Placebo N=300 |
|---|---|---|
| Dizziness Includes vertigo | 15.6% | 9.0% |
| Somnolence | 3.0% | 1.0% |
| Hypotension | 1.7% | 0% |
| Dyspnoea | 2.6% | 0.3% |
| Dry Mouth | 1.4% | 0.3% |
| Fatigue | 8.0% | 1.7% |
| Oedema | 2.7% | 0.7% |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe 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 CARDURA 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 CARDURA vs. placebo are summarized in Table 1. Table 1.
Source: FDA drug label, Viatris Specialty LLC, effective October 15, 2023 (SPL set 5e1f5e49-2da1-43ab-9795-228a8bcc5a82), via openFDA; the full label on DailyMed
What do FAERS reports show?
35,891 reports list doxazosin among the medicines taken, each a report of something that happened, not proof the medicine caused it; 3,117 are coded as a death and 15,209 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 19 reactions below, 8 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Doxazosin: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions