Tamsulosin

What it is

Tamsulosin is an alpha-1 adrenoceptor blocker with selectivity for the alpha-1A subtype found in the prostate and bladder neck. Blocking these receptors relaxes the smooth muscle there, which eases the flow of urine without shrinking the gland itself. It is used for the urinary symptoms of an enlarged prostate.

A usual adult range, not a national label — the dose and the timing differ by country and by product.

Used for

• Prostate

Approved uses differ by country — some of these may be off-label or unapproved where you live.

What to know while taking it

It is taken once in the morning after a meal, since food steadies absorption and a consistent daily timing keeps the effect even. Alpha blockade also affects blood vessels, so blood pressure can drop, particularly with the first doses; standing up slowly from bed or a chair reduces the light-headedness that follows. Erectile dysfunction drugs such as sildenafil and tadalafil lower blood pressure by a different route and the two effects add together, which is worth raising with the prescriber. Anyone due for cataract or other eye surgery should tell the surgeon that this drug is or has been taken, because it changes how the iris behaves during the operation, and that holds even long after treatment ends.

When to see a doctor

Fainting, near-fainting or repeated severe dizziness on standing needs medical assessment. Inability to pass urine at all, blood in the urine, fever with pain in the flank, or a prolonged painful erection are reasons to see a doctor without delay.

Worth knowing

• Can lower blood pressure
• Stand up slowly
• Tell the surgeon before cataract surgery