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What the label lists and what reports show

Prazosin side effects

Prazosin's FDA label lists its adverse reactions in its own words. FAERS holds 7,384 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 nausea (467 reports).

  • Generic listed
  • A presentation discontinued

Check it at the source: the prazosin FDA label on DailyMed (effective March 6, 2026, Prasco Laboratories); the FDA FAERS public dashboard.

What does the label list?

From the label: adverse reactions

Clinical trials were conducted on more than 900 patients. During these trials and subsequent marketing experience, the most frequent reactions associated with prazosin hydrochloride therapy are: dizziness 10.3%, headache 7.8%, drowsiness 7.6%, lack of energy 6.9%, weakness 6.5%, palpitations 5.3%, and nausea 4.9%. In most instances, side effects have disappeared with continued therapy or have been tolerated with no decrease in dose of drug. Less frequent adverse reactions which are reported to occur in 1–4% of patients are: Gastrointestinal: vomiting, diarrhea, constipation. Cardiovascular: edema, orthostatic hypotension, dyspnea, syncope. Central Nervous System: vertigo, depression, nervousness. Dermatologic: rash. Genitourinary: urinary frequency. EENT: blurred vision, reddened sclera, epistaxis, dry mouth, nasal congestion. …

Source: FDA drug label, NDA017442 (Pfizer), as published by Prasco Laboratories, effective March 6, 2026 (SPL set cbe89216-7dea-43d7-b12e-44ccfb69af3d), via openFDA; the full label on DailyMed

What do FAERS reports show?

7,384 reports list prazosin among the medicines taken, each a report of something that happened, not proof the medicine caused it; 799 are coded as a death and 2,634 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, 10 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

  • Drug Ineffective (a use or a product term, not a reaction)484
  • Off Label Use (a use or a product term, not a reaction)484
  • Nausea (named in the label)467
  • Fatigue373
  • Headache (named in the label)338
  • Pain327
  • Dizziness (named in the label)326
  • Diarrhoea (named in the label)313
  • Vomiting (named in the label)309
  • Anxiety307
  • Depression289
  • Dyspnoea (named in the label)283
  • Hypotension (named in the label)276
  • Fall274
  • Suicidal Ideation251
  • Drug Interaction (a use or a product term, not a reaction)248
  • Completed Suicide (an outcome recorded in the report)235
  • Toxicity To Various Agents232
  • Product Dose Omission Issue (a use or a product term, not a reaction)210
  • Abdominal Pain193
  • Insomnia (named in the label)185
  • Arthralgia (named in the label)183
  • Condition Aggravated (a use or a product term, not a reaction)178
  • Malaise (named in the label)178
  • Acute Kidney Injury177

Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms

What next?

Prazosin: the full record
label, generics, price, shortages, recalls
Side effects hub
the most reported medicines and reactions