Lyng Pharmacy
Medicines A–Z · Alpha blocker

Tamsulosin

For an enlarged prostate · Written by the Lyng Pharmacy team, based on NHS and BNF guidance · Updated August 2026
Also sold asFlomax, Flomaxtra
Type of medicineAlpha blocker
Available asCapsules, modified-release tablets
How you get itPrescription only; a pharmacy supply exists for some men

Tamsulosin relaxes the muscle in the prostate and bladder neck, making it easier to pass urine. It works within days rather than weeks, which makes it noticeably satisfying compared with the alternative prostate medicines.

What it is used for

Urinary symptoms of an enlarged prostate — a weak stream, hesitancy, dribbling, getting up at night, and a feeling of not emptying fully. It is sometimes used to help pass a kidney stone.

It relieves symptoms; it does not shrink the prostate. Finasteride does that, and the two are sometimes used together.

How to take it

Once daily, after the same meal each day — usually breakfast. Swallow whole; do not crush or chew.

The first dose can cause noticeable dizziness or lightheadedness, so many people take the first one at bedtime. Get up slowly from sitting or lying for the first few days.

Improvement is usually noticeable within a week or two.

The eye surgery warning

Tell your eye surgeon that you take tamsulosin before any cataract or glaucoma surgery, even if you stopped it long ago. It can cause a complication during surgery called floppy iris syndrome, which the surgeon can plan around if they know in advance.

Side effects and cautions

Dizziness, headache, a runny or blocked nose, and abnormal ejaculation (reduced or absent semen) are the common ones. The ejaculation effect is harmless but surprising if unexpected.

Get medical advice for fainting, a persistent painful erection lasting more than four hours (seek urgent help), or swelling of the face or throat.

Alcohol and hot weather add to the dizziness. Tell your prescriber about other blood pressure medicines and about medicines for erectile dysfunction, which can compound the drop in blood pressure.

New or worsening urinary symptoms, blood in the urine, or unexplained weight loss should be assessed rather than simply treated.

Always read the label. This page is general information, not advice for your situation. Doses, warnings and interactions differ between products and between people. Check the leaflet inside your medicine, and ask our pharmacist if anything is unclear — that conversation is free and takes two minutes.

Questions about Tamsulosin?

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Frequently asked questions

How quickly does tamsulosin work?
Usually within a week or two, which is faster than finasteride. It relieves symptoms rather than shrinking the prostate.
Why does tamsulosin affect ejaculation?
It relaxes muscle at the bladder neck, which commonly reduces or removes the volume of semen. It is harmless but surprising if you are not expecting it.
Do I need to tell my eye surgeon I take tamsulosin?
Yes, even if you stopped it long ago. It can cause a complication during cataract surgery that the surgeon can plan around if they know.
When should I take tamsulosin?
Once daily after the same meal each day. Many people take the first dose at bedtime because of initial dizziness.

Related pages

Finasteride →Free medicine review →All medicines A–Z →

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