What the label lists and what reports show
Tamsulosin side effects
Tamsulosin's FDA label: “The most common adverse events (≥2% of patients and at a higher incidence than placebo) with the 0.4 mg dose or 0.8 mg dose were headache, dizziness, rhinitis, infection, abnormal ejaculation, asthenia, back pain, diarrhea, pharyngitis, chest pain, cough …” FAERS holds 20,287 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 fatigue (1,513 reports).
- Generic listed
Check it at the source: the tamsulosin FDA label on DailyMed (effective December 1, 2025, Synthon Pharmaceuticals, Inc.); 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 tamsulosin hydrochloride capsules?Possible side effects of tamsulosin hydrochloride capsules may include: Decreased blood pressure when changing positions. Tamsulosin hydrochloride capsules may cause a sudden drop in blood pressure upon standing, especially after the first dose or when changing doses. Symptoms may include: fainting dizziness lightheadedness Change positions slowly from lying down to sitting up or from a sitting to a standing position until you learn how you react to tamsulosin hydrochloride capsules. If you begin to feel dizzy, sit or lie down until you feel better. If the symptoms are severe or do not improve, call your doctor. Allergic reactions. Make your doctor aware of any allergic reactions you may experience while taking tamsulosin hydrochloride capsules. Allergic reactions may include: rash itching hives Rare and more serious allergic reactions may also occur. […]
Source: FDA drug label, Synthon Pharmaceuticals, Inc., effective December 1, 2025 (SPL set 13a5032d-0be1-4001-916e-459f0b1a051d), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse events (≥2% of patients and at a higher incidence than placebo) with the 0.4 mg dose or 0.8 mg dose were headache, dizziness, rhinitis, infection, abnormal ejaculation, asthenia, back pain, diarrhea, pharyngitis, chest pain, cough increased, somnolence, nausea, sinusitis, insomnia, libido decreased, tooth disorder, and blurred vision ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Synthon at 919-493-6006 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
Table 1: Treatment-Emergent A treatment-emergent adverse event was defined as any event satisfying one of the following criteria: The adverse event occurred for the first time after initial dosing with double-blind…
| Reaction | BODY SYSTEM/ ADVERSE EVENT 0.4 mg n=502 | TAMSULOSIN HYDROCHLORIDE CAPSULES GROUPS 0.8 mg n=492 | PLACEBO n=493 |
|---|---|---|---|
| Headache | 97 (19.3%) | 104 (21.1%) | 99 (20.1%) |
| Infection Coding preferred terms also include cold, common cold, head cold, flu, and… | 45 (9.0%) | 53 (10.8%) | 37 (7.5%) |
| Asthenia | 39 (7.8%) | 42 (8.5%) | 27 (5.5%) |
| Back pain | 35 (7.0%) | 41 (8.3%) | 27 (5.5%) |
| Chest pain | 20 (4.0%) | 20 (4.1%) | 18 (3.7%) |
| Dizziness | 75 (14.9%) | 84 (17.1%) | 50 (10.1%) |
| Somnolence | 15 (3.0%) | 21 (4.3%) | 8 (1.6%) |
| Insomnia | 12 (2.4%) | 7 (1.4%) | 3 (0.6%) |
| Libido decreased | 5 (1.0%) | 10 (2.0%) | 6 (1.2%) |
| Rhinitis Coding preferred terms also include nasal congestion, stuffy nose, runny nose,… | 66 (13.1%) | 88 (17.9%) | 41 (8.3%) |
| Pharyngitis | 29 (5.8%) | 25 (5.1%) | 23 (4.7%) |
| Cough increased | 17 (3.4%) | 22 (4.5%) | 12 (2.4%) |
| Sinusitis | 11 (2.2%) | 18 (3.7%) | 8 (1.6%) |
| Diarrhea | 31 (6.2%) | 21 (4.3%) | 22 (4.5%) |
| Nausea | 13 (2.6%) | 19 (3.9%) | 16 (3.2%) |
| Tooth disorder | 6 (1.2%) | 10 (2.0%) | 7 (1.4%) |
| Abnormal ejaculation | 42 (8.4%) | 89 (18.1%) | 1 (0.2%) |
| Blurred vision | 1 (0.2%) | 10 (2.0%) | 2 (0.4%) |
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 common adverse events (≥2% of patients and at a higher incidence than placebo) with the 0.4 mg dose or 0.8 mg dose were headache, dizziness, rhinitis, infection, abnormal ejaculation, asthenia, back pain, diarrhea, pharyngitis, chest pain, cough increased, somnolence, nausea, sinusitis, insomnia, libido decreased, tooth disorder, and blurred vision ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Synthon at 919-493-6006 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 reactions 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. The incidence of treatment-emergent adverse events has been ascertained from six short-term U.S. and European placebo-controlled clinical trials in which daily doses of 0.1 to 0.8 mg tamsulosin hydrochloride capsules were used. These studies evaluated safety in 1783 patients treated with tamsulosin hydrochloride capsules and 798 patients administered placebo. Table 1 summarizes the treatment-emergent adverse events that occurred in ≥2% of patients receiving either tamsulosin hydrochloride capsules 0.4 mg or 0.8 mg and at an incidence numerically higher than that in the placebo group during two 13-week U.S. …
Source: FDA drug label, Synthon Pharmaceuticals, Inc., effective December 1, 2025 (SPL set 13a5032d-0be1-4001-916e-459f0b1a051d), via openFDA; the full label on DailyMed
What do FAERS reports show?
20,287 reports list tamsulosin among the medicines taken, each a report of something that happened, not proof the medicine caused it; 2,204 are coded as a death and 7,120 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 21 reactions below, 12 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?
- Tamsulosin: 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