An alpha-blocker for prostate symptoms
Silodosin
An alpha-blocker that relaxes the prostate and bladder neck to ease the urinary symptoms of an enlarged prostate.
What is Silodosin?
Silodosin is an alpha-blocker used to ease the urinary symptoms of an enlarged prostate (benign prostatic hyperplasia) in men, such as a weak stream, hesitancy and needing to pass urine often. It relaxes the muscle in the prostate and bladder neck so urine flows more easily. A very common and harmless effect is reduced or absent ejaculation, and it can cause dizziness, especially when standing. If you are due cataract or other eye surgery, tell the eye surgeon you take it, as it can affect the iris during the operation.
Education and reference only. This is a plain-language guide to Silodosin — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Silodosin is a medicine called an alpha-blocker, used in men to relieve the urinary symptoms caused by an enlarged prostate gland (benign prostatic hyperplasia, or BPH). As the prostate enlarges with age it can squeeze the tube that carries urine, leading to a weak or slow stream, difficulty starting, dribbling and needing to pass urine often or urgently. Silodosin is taken as a capsule once a day and works fairly selectively on the prostate, which is why it tends to lower blood pressure less than some other alpha-blockers but very often affects ejaculation.
How it works
Silodosin blocks particular receptors (alpha-1A receptors) found mainly in the muscle of the prostate and bladder neck. By relaxing this muscle, it opens up the outflow from the bladder so urine can pass more freely, easing symptoms such as a weak stream and the need to strain. Because it acts fairly selectively on the prostate rather than blood vessels, it usually has a smaller effect on blood pressure than older alpha-blockers, but this same selective action commonly reduces or stops the release of semen during orgasm.
Company & origin
Originated / developed by: Recordati.
An alpha-blocker used in the UK to ease the urinary symptoms of an enlarged prostate (benign prostatic hyperplasia).
What it treats
Conditions Silodosin is used for
Practical use
How to take Silodosin
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take one capsule once a day, usually with food, at about the same time each day.
- Swallow the capsule whole with a drink of water.
- Stand up slowly, especially when you first start, as it can cause dizziness or light-headedness.
- Expect that your ejaculation may be reduced or absent; this is harmless and reverses if you stop the medicine.
- Tell any eye surgeon that you take or have taken silodosin before cataract or other eye surgery.
Weighing it up
Advantages & disadvantages of Silodosin
Advantages
- Effectively eases bothersome urinary symptoms of an enlarged prostate, such as a weak stream and frequent urination.
- Works fairly selectively on the prostate, so it tends to lower blood pressure less than some other alpha-blockers.
- Taken simply as one capsule a day, with symptoms often improving within the first week or two.
Disadvantages
- Very commonly reduces or stops the appearance of semen during orgasm, which can be unexpected.
- Can cause dizziness, light-headedness or a stuffy nose, especially at first.
- Eases symptoms but does not shrink the prostate or cure the underlying enlargement.
Practical use
Good to know
The effect that surprises most men is on ejaculation: silodosin very commonly reduces the amount of semen or stops it appearing altogether (the orgasm sensation usually remains). This is harmless and reverses if the medicine is stopped, but it is worth knowing in advance. Dizziness or light-headedness can happen, particularly when you first start or stand up quickly, so take care until you know how it affects you. A very important point is to tell any eye surgeon, well before cataract or other eye surgery, that you take or have taken silodosin, because alpha-blockers can cause a 'floppy iris' during the operation that the surgeon can manage if they know in advance. It eases symptoms rather than shrinking the prostate, so it does not cure the underlying enlargement.
Who should not take it / use with caution
- It is for men with prostate symptoms and is not used in women or children.
- People with severe liver or kidney problems may not be able to take it or may need careful assessment.
- It should be used with caution alongside certain other medicines that can lower blood pressure or that strongly affect how it is broken down.
Monitoring
- Reviewing whether urinary symptoms have improved and whether side effects such as dizziness are tolerable.
- Checking for and explaining the common effect on ejaculation.
- Reminding you to tell eye surgeons before any cataract or other eye operation.
Side effects
- Reduced or absent ejaculation is very common and harmless, and reverses if the medicine is stopped.
- Dizziness, light-headedness on standing, and a blocked or runny nose can occur.
- Less often headache, diarrhoea or a fast heartbeat; rarely, fainting or an allergic reaction.
Key interactions
- Other blood-pressure-lowering medicines, including those for erectile problems, can add to dizziness or low blood pressure.
- Medicines that strongly affect liver enzymes (such as some antifungals and certain antibiotics) can raise silodosin levels.
- Drinking alcohol may add to dizziness, so take care, especially when you first start.
Available as: Capsules taken by mouth once a day.
Answers
Silodosin: frequently asked questions
Why is there little or no semen when I climax?
Silodosin very commonly reduces or stops the release of semen during orgasm. This is harmless, the orgasm sensation usually remains, and it reverses if the medicine is stopped.
Will it make me dizzy?
It can cause dizziness or light-headedness, especially when you first start or stand up quickly, so rise slowly until you know how it affects you.
Why do I need to tell my eye surgeon?
Alpha-blockers like silodosin can cause a 'floppy iris' during cataract or other eye surgery, which the surgeon can manage if you tell them you take or have taken it.
Does it shrink my prostate?
No. It relaxes the muscle to ease symptoms but does not shrink the prostate; sometimes it is combined with a different medicine that does shrink it.
How quickly will it work?
Many men notice their urinary symptoms ease within the first week or two of taking it regularly.
The wider class
About Alpha-blocker (BPH)
Silodosin belongs to the alpha-blocker (bph) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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