Tamsulosin: enlarged prostate symptoms and what to expect

Tamsulosin is one of the alpha blockers. Its main use is to treat symptoms in men whose prostate has enlarged and is squeezing the urine channel: a weak stream, hesitancy, dribbling and getting up at night. The NHS also notes occasional use for kidney stones, where it may help a stone pass, and for prostatitis.

By relaxing the muscle at the bladder neck and in the prostate, tamsulosin lets you pass urine more easily. Alpha blockers also relax blood vessels, which is why they can lower blood pressure and cause dizziness.

Tamsulosin comes as slow-release tablets and capsules, sometimes labelled modified release, prolonged release, MR or XL. Brands the NHS lists include Contiflo XL, Faramsil MR, Flomaxtra XL, Pamsvax XL, Tabphyn MR, Cositam XL, Losinate MR, Omsula MR, Tamfrex XL, Tamsumac MR and Tamurex MR. The NHS also lists the combination products Vesomni, which contains solifenacin as well, and Combodart.

It is a prescription medicine, with Flomax Relief the one brand sold in pharmacies without a prescription. If you buy it that way, the NHS advises seeing a GP within 6 weeks to confirm it is still right for you.

The usual dose for enlarged prostate and kidney stones is 400 micrograms once a day. Swallow it with water while sitting or standing and, if you can, take it in the morning after breakfast or after your first meal or snack, at about the same time each day.

For an enlarged prostate it is generally continued long-term if it helps, with periodic review of how well it is working. For kidney stones the doctor may stop it once the stone has passed or if it is not helping.

• If you remember on the same day, take it then; if you remember the next day, skip it and carry on as normal.

• Never take two doses to make up for a forgotten one.

• Too much can lower blood pressure and raise heart rate; lying down may help, and the NHS says to contact NHS 111 for advice now if you take more than prescribed.

Most adults aged 18 and over can take it, and it is not normally given to children unless a paediatric specialist prescribes it. Tell the prescriber if you have had an allergic reaction to tamsulosin or similar alpha blockers such as alfuzosin, doxazosin, prazosin or terazosin; have orthostatic hypotension, a drop in blood pressure that causes dizziness on standing; have severe liver or kidney problems; are due to have cataract or glaucoma surgery; or have ever fainted while passing urine or just afterwards.

Dizziness and sweating, especially when sitting up or standing, are common. If they occur, stop what you are doing and sit or lie down until they pass, and avoid driving, cycling, machinery and alcohol while you feel unsteady. Reduced or absent semen on ejaculation is also common; the NHS says it is harmless, but mention it to your doctor if it bothers you.

Call NHS 111 if you faint or lose consciousness. Call 999 or go to A&E for new swelling under the skin or in the mouth, face, lips, tongue or throat (angioedema), or for a painful erection lasting 2 hours or longer (priapism). Anaphylaxis, with swelling of the lips, mouth or throat, struggling to breathe or collapse, is also a 999 emergency.

Suspected side effects can be reported through the Yellow Card scheme.

Other alpha blockers can lower blood pressure too far, as can blood pressure medicines, nitrates, some antidepressants, baclofen and Parkinson's medicines such as co-careldopa. The NHS also asks for caution with erection medicines (sildenafil, tadalafil and vardenafil), with ketoconazole, erythromycin and clarithromycin, which may slow tamsulosin's clearance, and with diclofenac and warfarin, which may speed it. Diclofenac specifically should not be combined with it.

Paracetamol, codeine and non-steroidal painkillers such as ibuprofen can be taken with tamsulosin. There is not enough information to call other herbal remedies safe.

Tamsulosin is not usually recommended in pregnancy, and it may be used during breastfeeding if the baby is healthy, after medical advice. Ejaculation problems mean couples trying to conceive should speak to a doctor if the man takes it.

Alcohol can add to the blood-pressure-lowering effect, so avoid it in the first days. If you feel dizzy do not drive, cycle or use tools. Tell any surgeon about tamsulosin before an operation; for cataract or glaucoma surgery you may need to stop it 1 to 2 weeks beforehand.