Sildenafil for erectile dysfunction
Aronix, Viagra
Granskad av Sid DajaniSenast uppdaterad av Michael Stewart, MRPharmSLast updated 18 Jan 2024
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Sildenafil is for the treatment of adult men with erectile dysfunction.
Take a tablet about an hour before you plan to have sex. Do NOT take more than one dose in 24 hours.
When you collect your prescriptions, check the brand and strength of the tablets. If the appearance is not the same as usual, speak with your doctor or pharmacist for further advice.
At a glance
Sildenafil helps to improve blood flow to the penis for men with erectile dysfunction.
It is taken about an hour before sexual activity and is not for continuous daily use.
Do not take more than one dose in 24 hours.
Avoid large amounts of alcohol and grapefruit juice when taking sildenafil.
Seek immediate medical help if an erection lasts over four hours, or if you get chest pains or sudden vision loss.
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About sildenafil for erectile dysfunction
Typ av medicin | Phosphodiesterase type-5 inhibitor |
Används för | Erectile dysfunction in adult men |
Även kallad | Aronix®; Liberize®; Viagra®; Vizarsin®; Zamantos®; |
Tillgänglig som | Tabletter |
Erectile dysfunction (sometimes called impotence) means that you cannot get or maintain a proper erection. There are several causes, the most common being due to a narrowing of the arteries that take blood to the penis.
Sildenafil works by preventing the action of a chemical in your body, called phosphodiesterase type-5. This helps to widen (relax) blood vessels and improves the flow of blood to the penis following sexual stimulation. This helps to maintain an erection.
Sildenafil is available on prescription. Non-branded (generic) tablets of sildenafil are available on the NHS, but the brand Viagra® can only be prescribed on the NHS for men with erectile dysfunction resulting from certain medical conditions.
Sildenafil can also be bought over the counter from pharmacies in certain circumstances. Ask your pharmacist for advice on whether this option is suitable for you.
Another brand of sildenafil tablets called Revatio® is used in a completely different condition called pulmonary arterial hypertension - please see the separate medicine leaflet called Sildenafil for pulmonary hypertension if you have been prescribed this brand of sildenafil tablets.
Before taking sildenafil
Tillbaka till innehållSome medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking sildenafil it is important that your doctor knows:
If you have any disease, injury or deformity of your penis.
If you have a heart condition, or blood vessel disease.
If you have had an eye condition causing loss of vision.
If you have low blood pressure or angina.
If you have any problems with the way your liver works or with the way your kidneys work.
If you have had a stroke or a heart attack.
If you have a condition which causes bleeding, such as a stomach ulcer.
If you have sickle cell disease.
If you have ever had bone marrow cancer or leukaemia.
If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines, and recreational drugs.
Om du någonsin har haft en allergisk reaktion mot en medicin.
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How to take sildenafil for erectile dysfunction
Tillbaka till innehållBefore you take sildenafil, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about the tablets and will provide you with a full list of the side-effects which you may experience from taking them.
Take sildenafil exactly as your doctor tells you to. It is intended to be taken before sexual activity - it is NOT for continuous daily use. You should take one tablet about an hour before you plan to have sex, although it may still be effective up to five hours after taking the tablet. You can take the tablet either before or after food but, if you have just eaten a large meal, it may take longer for it to work.
There are three strengths of sildenafil tablets: 25 mg, 50 mg and 100 mg. It is likely that you will be given the 50 mg strength tablet to begin with, but this may be changed subsequently depending upon how you react. Each time you collect a prescription, check to make sure it contains the strength of tablet you are expecting.
Do not take more than one dose of sildenafil in any 24-hour period.
Få ut det mesta av din behandling
Tillbaka till innehållYou and your partner will still need to engage in foreplay, just as you would if you were not taking a medicine for erectile dysfunction. Sildenafil will not cause an erection unless you are sexually aroused.
Do not drink large amounts of alcohol before you plan to take sildenafil. Drinking too much alcohol can reduce your ability to get an erection and this may prevent you from getting the maximum benefit from the tablets.
It is recommended that you do not drink grapefruit juice with sildenafil. This is because there is a chemical in grapefruit juice which can increase the amount of sildenafil in your bloodstream and this makes side-effects more likely.
Keep your regular appointments with your doctor so your progress can be monitored. If you feel the tablets are too strong for you, discuss this with your doctor as your dose may need to be reduced. Alternatively, if you do not get an erection after taking sildenafil, or if it does not last long enough for you to have sex, you should discuss this with your doctor - do not take more tablets than you have been told to.
You should not take sildenafil if you are using any other products or taking any other medicines to treat erectile dysfunction.
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Can sildenafil cause problems?
Tillbaka till innehållAlong with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with sildenafil. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.
Very common sildenafil side-effects (these affect more than 1 in 10 men) | Vad kan jag göra om jag upplever detta? |
Huvudvärk | Drink plenty of water. If the headaches continue, let your doctor know |
Common sildenafil side-effects (these affect fewer than 1 in 10 men) | Vad kan jag göra om jag upplever detta? |
Flushing, feeling sick, indigestion, blocked nose | These should soon pass |
Feeling dizzy, visual changes such as blurred vision or colour distortion | If either of these happen, do not drive and do not use tools or machines until your reactions/vision have returned to normal |
Viktigt: if your erection lasts for longer than four hours, or if you get chest pains or a sudden loss of vision, contact a doctor for medical attention omedelbart.
Om du upplever några andra symtom som du tror kan bero på tabletterna, tala med din läkare eller apotekare för vidare råd.
How to store sildenafil
Tillbaka till innehållFörvara alla läkemedel utom räckhåll och synhåll för barn.
Förvara på en sval, torr plats, borta från direkt värme och ljus.
Viktig information om alla läkemedel
Tillbaka till innehållViktig information om alla läkemedel
Om du köper några mediciner, kontrollera med en apotekare att de är säkra att ta tillsammans med dina andra mediciner.
Ta aldrig mer än den föreskrivna dosen. Om du misstänker att du eller någon annan kan ha tagit en överdos av denna medicin, gå till akutmottagningen på ditt lokala sjukhus. Ta med behållaren, även om den är tom.
Om du ska genomgå en operation eller tandbehandling, informera den som utför behandlingen om vilka mediciner du tar.
Denna medicin är för dig. Ge den aldrig till andra människor även om deras tillstånd verkar vara detsamma som ditt.
Behåll inte föråldrade eller oönskade mediciner. Ta dem till ditt lokala apotek som kommer att ta hand om dem åt dig.
Om du har några frågor om denna medicin, fråga din apotekare.
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Vanliga frågor
Can I get sildenafil without a prescription on the NHS?
Non-branded (generic) sildenafil tablets are available on the NHS with a prescription. However, the brand Viagra® can only be prescribed on the NHS for men who have erectile dysfunction caused by specific medical conditions. It can also be bought over the counter from pharmacies in certain circumstances, and you should ask your pharmacist for advice on whether this is a suitable option for you.
How soon before sex should I take sildenafil and how long does it work for?
You should take one sildenafil tablet about an hour before you plan to have sex. It can still be effective for up to five hours after you take it. You can take it either with or without food, but if you've eaten a large meal, it might take longer for the medicine to start working.
What should I do if the sildenafil doesn't work or the side-effects are too strong?
If you don't get an erection after taking sildenafil, or if the erection doesn't last long enough for you to have sex, you should discuss this with your doctor. Do not take more tablets than you have been told to. Conversely, if you feel the tablets are too strong, you should also talk to your doctor as your dose might need to be reduced.
Are there any specific foods or drinks I should avoid while taking sildenafil?
Yes, you should avoid drinking large amounts of alcohol before taking sildenafil, as this can reduce its effectiveness. It's also recommended not to drink grapefruit juice with sildenafil. This is because a chemical in grapefruit juice can increase the amount of sildenafil in your bloodstream, making side-effects more likely.
If I experience side-effects like a headache or dizziness, what should I do?
For headaches, you can try drinking plenty of water. If headaches continue, inform your doctor. If you experience dizziness, blurred vision, or colour distortion, do not drive or use tools or machines until your reactions and vision have returned to normal. Most common side-effects often improve as your body adjusts, but speak with your doctor or pharmacist if any continue or become bothersome.
Can I take sildenafil if I am using other treatments for erectile dysfunction?
No, you should not take sildenafil if you are using any other products or taking any other medicines specifically to treat erectile dysfunction.
What is the difference between sildenafil for erectile dysfunction and Revatio®?
Sildenafil is used for erectile dysfunction, which is when you cannot get or maintain a proper erection. Another brand of sildenafil called Revatio® is used for a completely different condition known as pulmonary arterial hypertension. If you have been prescribed Revatio®, you should refer to the specific information leaflet for Sildenafil for pulmonary hypertension.
Vidare läsning och referenser
- Manufacturer's PIL, Viagra® 25 mg, 50 mg, 100 mg tablets; Upjohn UK Ltd, The electronic Medicines Compendium. Dated December 2023.
- Mediciner Komplett BNF 89:e Utgåvan; Brittiska Läkarföreningen och Kungliga Farmaceutiska Sällskapet i Storbritannien, London.
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About the authorView full bio

Michael Stewart, MRPharmS
Medicine Leaflet Review Manager – Contractor, Pharmacist
BPharm (Hons), MRPharmS
Michael is a community pharmacist practicing in the Midlands and South Yorkshire with more than 20 years’ experience advising on medicines and medical conditions. He has a strong background in healthcare training, having produced and delivered training courses for pharmacy teams and staff of residential care settings, including nurses. He has also contributed to pharmacy advisory boards for the management of low acuity conditions in the community.
About the reviewer

Sid Dajani
Sultan Dajani qualified at the London School of Pharmacy in 1994 and became the youngest elected member of the Royal Pharmaceutical Society council since its founding in 1842.
Artikelhistorik
Informationen på denna sida är skriven och granskad av kvalificerade kliniker.
Next review due: 17 Jan 2027
18 Jan 2024 | Senaste versionen

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