doxazosin vs tamsulosin
Side-by-side comparison of doxazosin and tamsulosin Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
Cardura
Flomax
Doxazosin is a medicine that can help lower high blood pressure and improve symptoms of an enlarged prostate in men.
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.
Doxazosin is used to treat high blood pressure (hypertension). Lowering blood pressure reduces the risk of strokes and heart attacks. It is also used to treat the symptoms of Benign Prostatic Hyperplasia (BPH), also known as an enlarged prostate, in men.
This medicine treats the symptoms of an enlarged prostate, also known as benign prostatic hyperplasia (BPH). BPH can cause problems with urination, like difficulty starting or stopping the flow of urine. Tamsulosin helps to relieve these symptoms.
Doxazosin belongs to a class of drugs called alpha-1 adrenergic blockers. It works by relaxing the muscles in the prostate and bladder neck, making it easier to urinate. It also relaxes blood vessels, which helps to lower blood pressure.
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.
- • Dizziness
- • Feeling tired
- • Low blood pressure
- • Swelling
- • Runny nose
- • Headache
- • Dizziness
- • Runny nose
- • Infection
- • Abnormal ejaculation
- Shortness of breath 1,478
- Feeling unsteady 1,295
- Feeling very tired 1,276
- Medication not working 1,251
- Loose stools 1,237
- Tiredness 1,417
- Shortness of breath 1,332
- Feeling lightheaded 1,131
- Loose stools 1,121
- Using the medicine for something it's not approved for 961
Doxazosin can cause your blood pressure to drop suddenly when you stand up, leading to dizziness or fainting. This is more likely when you first start taking it or when the dose is increased. If you are having cataract surgery, tell your doctor you are taking this medicine. Doxazosin has been linked to priapism (a painful erection lasting for hours). If this happens, seek medical attention right away.
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.
It is not known if doxazosin can harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant. Doxazosin does pass into breast milk in small amounts. Talk to your doctor about the best way to feed your baby if you are taking doxazosin.
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.
How to Read This doxazosin vs tamsulosin Comparison
doxazosin is classified in the Alpha-1 Adrenergic Blocker drug class, while tamsulosin sits within the Alpha-1 Adrenergic Blocker class. Because both drugs share the same classification, they are often considered interchangeable in theory — but clinical outcomes rarely track that cleanly. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, doxazosin has 6,537 submissions while tamsulosin has 5,962. Those figures reflect cumulative reporting volume — not per-patient risk — so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between doxazosin and tamsulosin — always consult your physician or pharmacist first.
Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.