BMA Concise Guide to Medicine & Drugs


Brand names Diffundox XL, Flomaxtra XL, Stronazon MR, Tabphyn MR

Used in the following combined preparations Combodart (with dutaseride), Vesomni (with solifenacin)


Drug group Drug for urinary disorders

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes (most preparations)

Available as generic Yes


Tamsulosin is a selective alpha-blocker drug used to treat urinary retention due to benign prostatic hypertrophy, or BPH (enlarged prostate gland). The drug, as it passes through the prostate, relaxes the muscle in the wall of the urethra, thereby increasing urine flow.

Tamsulosin is available over-the-counter for men aged 45–74 with symptoms of BPH. If symptoms have not improved (or have got worse) within two weeks, the drug should be stopped and you should consult your doctor. If symptoms have improved with the drug, you should still see your doctor within six weeks to confirm your symptoms are due to BPH.

Like other alpha-blockers, tamsulosin may lower blood pressure rapidly after the first dose. For this reason, the first dose should be taken at home so that, if dizziness or weakness occur, you can lie down until they have disappeared.


Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor. If taking an over-the-counter preparation, follow the instructions and consult your doctor if symptoms do not improve or worsen.

How taken/used Tablets, capsules.

Frequency and timing of doses Once daily, swallowed whole, after breakfast.

Adult dosage range 400mcg.

Onset of effect 1–2 hours.

Duration of action 24 hours.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember. If your next dose is due within 4 hours, take a single dose now and skip the next.

Stopping the drug Do not stop taking the drug without consulting your doctor; stopping suddenly may lead to a rise in blood pressure.

Exceeding the dose An occasional unintentional extra dose is unlikely to cause problems. Large overdoses may produce sedation, dizziness, low blood pressure, and rapid pulse. Notify your doctor immediately.


Dizziness seems to be the most common adverse effect of tamsulosin but this usually improves after the first few doses. Weakness, fainting, ejaculatory problems, headache, drowsiness, and palpitations are also common. Rarely, nausea, vomiting, and diarrhoea or constipation may occur. Discuss with your doctor if any of these symptoms are severe. If you develop a rash or itching, you should consult your doctor promptly.


Antidepressants, beta blockers, calcium channel blockers, diuretics, and thymoxamine These drugs are likely to increase the blood-pressure-lowering effect of tamsulosin.


Be sure to consult your doctor or pharmacist before taking this drug if:

· You have had low blood pressure.

· You have liver or kidney problems.

· You have heart failure.

· You have a history of depression.

· You are taking drugs for high blood pressure.

· You are taking other medicines.

· You have cataract surgery planned.

Pregnancy Not prescribed.

Breast-feeding Not prescribed.

Infants and children Not prescribed.

Over 60 No special problems.

Driving and hazardous work Avoid such activities until you have learned how tamsulosin affects you because the drug can cause drowsiness and dizziness.

Alcohol Avoid until you know how tamsulosin affects you because alcohol can further lower blood pressure.

Surgery and general anaesthetics Tamsulosin may need to be stopped. Discuss with your doctor or dentist before you have any surgery.


No special problems.