Tamsulosin
Also known as: Flomax, Flomaxtra
What it's for
Tamsulosin helps men with an enlarged prostate (benign prostatic hyperplasia). It relaxes the muscles in the prostate and bladder neck, making it easier to pass urine.
Comes as: Capsules or tablets
How to take it
- Adults: Usually 400 micrograms once daily.
- Take after breakfast or the first meal of the day.
- Swallow whole - do not crush or chew.
- It may take a few weeks to notice improvement.
Doses here are typical. Always follow the instructions from your prescriber or on the packet — they come first.
Common side effects
- Dizziness, especially when standing up
- Headache
- Abnormal ejaculation (reduced or no semen)
- Runny or blocked nose
The leaflet inside the packet lists all known side effects.
Important safety points
- Can cause dizziness when you first start - get up slowly
- Tell your eye surgeon if you are having cataract surgery
- May affect ejaculation - this is harmless but tell your doctor if it concerns you
- Do not take with similar medicines (other alpha-blockers)
Get medical help urgently if…
- You cannot pass urine at all
- You have a painful erection lasting more than 4 hours
- You faint or feel very dizzy
- You have signs of an allergic reaction
Call NHS 111 for urgent advice, or 999 if someone is seriously unwell.
Before you act on anything here
This page is general information, written to help you understand — it is not personal medical advice and it cannot tell you what is right for you. Talk to your own GP, pharmacist or nurse about your own health.
- Need help now but it's not an emergency? Call NHS 111 or use 111.nhs.uk.
- Emergency? Call 999 or go to A&E.