Tamsulosin

Key facts

• Tamsulosin is an alpha-blocker that relaxes smooth muscle in the prostate and bladder neck, easing urine flow in benign prostatic hyperplasia (BPH).
• You take it once daily, usually about 30 minutes after the same meal each day, and effects on urine flow can build over the first week or two.
• If you are scheduled for cataract surgery, tell your eye surgeon you take tamsulosin: it can cause intraoperative floppy iris syndrome, making surgery more difficult if the surgeon is not prepared for it.
• Seek urgent care for fainting, a painful erection lasting more than 4 hours, or chest pain.

What tamsulosin treats

Tamsulosin treats the urinary symptoms of benign prostatic hyperplasia (BPH): a weak stream, frequent urination, difficulty starting, and a feeling of incomplete emptying. It is sometimes used to help pass a kidney stone. It does not treat prostate cancer or a urinary tract infection, and these need to be ruled out separately.

How tamsulosin works

The prostate and bladder neck contain alpha-1 receptors that, when stimulated, keep the smooth muscle in these areas contracted, narrowing the outlet for urine. Tamsulosin blocks these receptors, relaxing the muscle and widening the outlet, so urine flows more easily.

Before you take it

• Tell your prescriber before any eye surgery, especially cataract surgery, because of the floppy iris risk.
• Tamsulosin can cause a marked drop in blood pressure, especially after the first dose or when standing up quickly; take the first dose at bedtime and rise slowly until you know how it affects you.
• Other blood-pressure-lowering medicines and PDE5 inhibitors, used for erectile dysfunction, can add to this effect.
• Tell your doctor about liver impairment and any history of low blood pressure or fainting.

Side effects

Common effects include dizziness, a runny or stuffy nose, and reduced or absent ejaculation.

Stop and seek urgent medical care for:

• Fainting or severe dizziness, especially with a fall.
• A painful erection lasting more than 4 hours (priapism).
• Chest pain or an irregular heartbeat.
• A severe allergic reaction: rash, swelling, or difficulty breathing.

Safety essentials

• Always tell your eye surgeon you take tamsulosin before cataract or other eye surgery; floppy iris syndrome can occur even if you stopped the drug some time ago.
• Orthostatic hypotension is common, particularly after the first dose; sit or lie down at the first sign of dizziness and stand up slowly afterward.
• Avoid combining tamsulosin with other blood-pressure-lowering medicines or PDE5 inhibitors without medical advice.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.