Prescription medication · Alpha-1 Adrenergic Blocker
tamsulosin
Also sold as Flomax. This medicine treats the symptoms of an enlarged prostate, also known as benign prostatic hyperplasia (BPH).
Data updated 2026-05-15
- 18,628
- FDA reportsModerately reported
- 18
- InteractionsSeveral interactions
- 99% less
- Generic vs brandHuge savings
- In shortage
- FDA status
What the data shows
tamsulosin (Flomax) is a prescription Alpha-1 Adrenergic Blocker, reported at a middle-of-the-pack volume (18,628 FDA reports), whose generic costs a fraction of the brand (about 99% less).
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
tamsulosin (Flomax) is a prescription Alpha-1 Adrenergic Blocker. This medicine treats the symptoms of an enlarged prostate, also known as benign prostatic hyperplasia (BPH).
Tamsulosin (Flomax) helps to improve urination in men with enlarged prostate glands. It relaxes the muscles in the prostate and bladder, making it easier to urinate.
Verify with FDA → · CMS NADAC pricing →
Drug Shortage Alert
tamsulosin is currently listed as to be discontinued by the FDA. Affected manufacturer: Sandoz Inc..
View all drug shortages →Drug Pricing (NADAC)
Brand Price
$9.35/unit
Generic Price
$0.05/unit
Generic Savings
99%
Generic Available
Yes (9 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine treats the symptoms of an enlarged prostate, also known as benign prostatic hyperplasia (BPH).
Common side effects
Headache, Dizziness, Runny nose
Key warnings
Tamsulosin can cause a sudden drop in blood pressure when you stand up, leading to dizziness or fainting.
The sections below are summarized in plain English from tamsulosin's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Tamsulosin blocks alpha-1 adrenoceptors in the prostate and bladder. These receptors control muscle tightness. By blocking them, tamsulosin relaxes the muscles, which improves urine flow.
How to Take It
Take one 0.4 mg capsule of tamsulosin each day. Take it about 30 minutes after the same meal every day. Do not crush, chew, or open the capsule. If the 0.4 mg dose doesn't work after 2 to 4 weeks, your doctor may increase the dose to 0.8 mg daily.
This is a plain-language summary of tamsulosin's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
This medicine is only for men. It is not meant to be used by women. There is no information about the safety of tamsulosin during pregnancy or breastfeeding because it is not used in women.
This is a plain-language summary of tamsulosin's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
This is a plain-language summary of tamsulosin's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store tamsulosin capsules at room temperature, away from heat and moisture, and keep out of reach of children.
Side Effects (from patient reports)
Based on 18,628 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for tamsulosin, by number of reports
- Tiredness
Tiredness
1,417 reports
- Shortness of breath
Shortness of breath
1,332 reports
- Feeling lightheaded
Feeling lightheaded
1,131 reports
- Loose stools
Loose stools
1,121 reports
- Head pain
Head pain
883 reports
- Weakness
Weakness
842 reports
- Accidental fall
Accidental fall
838 reports
- Feeling sick to your stomach
Feeling sick to your stomach
808 reports
- Coughing
Coughing
711 reports
- Feeling unwell
Feeling unwell
652 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for tamsulosin each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where tamsulosin sits
tamsulosin has more FDA adverse-event reports than 53% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is tamsulosin; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 18,628 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
18,628
Reports Mentioning Death
2,065
11.1% of reports — not proof of cause
Hospitalization Reports
6,635
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | FATIGUE | 1,417 |
| 2 | DYSPNOEA | 1,332 |
| 3 | DIZZINESS | 1,131 |
| 4 | DIARRHOEA | 1,121 |
| 7 | HEADACHE | 883 |
| 8 | ASTHENIA | 842 |
| 9 | FALL | 839 |
| 10 | NAUSEA | 808 |
| 11 | COUGH | 711 |
| 12 | MALAISE | 652 |
| 13 | PRURITUS | 651 |
| 14 | ARTHRALGIA | 644 |
| 15 | DEATH | 639 |
| 16 | DECREASED APPETITE | 601 |
| 17 | PYREXIA | 586 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Tamsulosin can cause a sudden drop in blood pressure when you stand up, leading to dizziness or fainting. Avoid situations where you could get hurt if you faint. Tell your eye doctor if you are planning to have cataract or glaucoma surgery, as tamsulosin can cause complications during the procedure. You should be screened for prostate cancer before starting tamsulosin and regularly after.
Known Drug Interactions
7.7 Furosemide Tamsulosin hydrochloride capsules had no effect on the pharmacodynamics (excretion of electrolytes) of furosemide. While furosemide produced an 11% to 12% reduction in tamsulosin hydrochloride C max and AUC, these changes are expected to be clinically insignificant and do not require adjustment of the tamsulosin hydrochloride capsules dosage [see Clinical Pharmacology (12.3)].
Mechanism: Furosemide slightly lowers the level of tamsulosin in your system, but the effect is too small to change how the medicine works.
What to do: You can take these medicines together safely without changing your dose.
Tamsulosin hydrochloride capsules should be used with caution in combination with moderate inhibitors of CYP3A4 (e.g., erythromycin), in combination with strong (e.g., paroxetine) or moderate (e.g., terbinafine) inhibitors of CYP2D6, or in patients known to be CYP2D6 poor metabolizers, particularly at a dose higher than 0.4 mg (e.g., 0.8 mg). Concomitant treatment with paroxetine (a strong inhibitor of CYP2D6) resulted in an increase in the C max and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)].
Mechanism: Paroxetine stops your body from breaking down tamsulosin normally, which leads to higher levels of the drug in your system. This can increase your risk of having side effects.
What to do: Use this combination with caution, especially if you are taking a higher dose of tamsulosin.
7.4 Warfarin A definitive drug-drug interaction study between tamsulosin hydrochloride and warfarin was not conducted. Caution should be exercised with concomitant administration of warfarin and tamsulosin hydrochloride capsules [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)].
Mechanism: There is not enough research to know exactly how these drugs interact, but taking them together might change how your blood clots. This could make your treatment less safe.
What to do: Use caution when taking these drugs together and follow your doctor's advice for monitoring.
Tamsulosin hydrochloride capsules should be used with caution in combination with moderate inhibitors of CYP3A4 (e.g., erythromycin), in combination with strong (e.g., paroxetine) or moderate (e.g., terbinafine) inhibitors of CYP2D6, or in patients known to be CYP2D6 poor metabolizers, particularly at a dose higher than 0.4 mg (e.g., 0.8 mg). The effects of concomitant administration of a moderate CYP3A4 inhibitor (e.g., erythromycin) on the pharmacokinetics of tamsulosin hydrochloride have not been evaluated [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)].
Mechanism: Erythromycin may slow down the way your body gets rid of tamsulosin, which could cause the drug to build up in your blood. This might lead to more side effects from the medicine.
What to do: Use this combination with caution, especially if your doctor has prescribed a higher dose of tamsulosin.
Tamsulosin hydrochloride capsules should be used with caution in combination with moderate inhibitors of CYP3A4 (e.g., erythromycin), in combination with strong (e.g., paroxetine) or moderate (e.g., terbinafine) inhibitors of CYP2D6, or in patients known to be CYP2D6 poor metabolizers, particularly at a dose higher than 0.4 mg (e.g., 0.8 mg). The effects of concomitant administration of a moderate CYP2D6 inhibitor (e.g., terbinafine) on the pharmacokinetics of tamsulosin hydrochloride have not been evaluated [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)].
Mechanism: Terbinafine slows down the body's ability to break down tamsulosin by blocking a specific liver enzyme. This can lead to higher levels of tamsulosin in your blood.
What to do: Use this combination with caution. Your doctor may need to adjust your dose, especially if you are taking more than 0.4 mg of tamsulosin.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
Common Questions
Can women take tamsulosin?
Can I crush or chew the capsule?
What should I do if I feel dizzy after taking tamsulosin?
Can I take tamsulosin with other medications?
How long does it take for tamsulosin to work?
What if tamsulosin doesn't work for me?
Does tamsulosin affect my sex life?
Can I drink alcohol while taking tamsulosin?
What if I am having surgery?
How do I know if tamsulosin is working?
What are the common side effects of tamsulosin?
Does tamsulosin interact with other medications?
What drug class is tamsulosin?
Is there a generic version of tamsulosin?
Is tamsulosin safe during pregnancy?
Is tamsulosin currently in shortage?
Related Medications in Alpha-1 Adrenergic Blocker
Other drugs grouped near tamsulosin - same-class peers and common alternatives.
alfuzosin
Uroxatral
Alfuzosin is a medicine that helps men with enlarged prostate glands.
Compare with tamsulosin →
bethanechol
Urecholine
Bethanechol helps you to urinate if you have trouble emptying your bladder.
Compare with tamsulosin →
darifenacin
Enablex
Darifenacin (Enablex) is a medicine that helps control an overactive bladder.
Compare with tamsulosin →
dutasteride
Avodart
Dutasteride and tamsulosin hydrochloride capsules contain two medicines to treat enlarged prostate in men.
Compare with tamsulosin →
dutasteride/tamsulosin
Jalyn
This medicine combines two drugs to treat enlarged prostate in men.
Compare with tamsulosin →
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
Why some drugs demand precise dosing and monitoring
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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What the FDA Data Shows for tamsulosin
The FDA label for tamsulosin (sold under brand names such as Flomax) classifies it as a prescription-only medication in the Alpha-1 Adrenergic Blocker class. This medicine treats the symptoms of an enlarged prostate, also known as benign prostatic hyperplasia (BPH). Official labeling lists 18 commonly reported side effects, including Headache, Dizziness, Runny nose.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 18,628 voluntary reports. The database also lists 18 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated major severity. NADAC pricing from CMS shows a generic unit cost of $0.05 versus $9.35 for the brand - a 99% generic savings.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC). Shortage status: FDA Drug Shortages Database.
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: January 1, 2026
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages