What is Sildenafil?

Sildenafil is a prescription medicine used to treat erectile dysfunction in adult men. It is the active ingredient found in Viagra, but generic sildenafil is supplied without the Viagra brand name.

This product is available in 25mg, 50mg and 100mg strengths. The strength prescribed will depend on your health, other medicines and previous response to treatment.

What is Sildenafil used for?

Sildenafil is used when a man cannot achieve or maintain an erection firm enough for satisfactory sexual activity.

It supports the natural erectile response by increasing blood flow to the penis. Sildenafil only works when you are sexually stimulated and does not increase sexual desire.

How does Sildenafil work?

Sildenafil belongs to a group of medicines called phosphodiesterase type 5 inhibitors, also known as PDE5 inhibitors.

During sexual stimulation, sildenafil helps the blood vessels in the penis relax. This allows more blood to enter the penis and makes it easier to achieve and maintain an erection.

How to take Sildenafil

Always follow the instructions provided by your prescriber.

• Take the prescribed tablet approximately one hour before sexual activity.
• Swallow the tablet whole with water.
• Do not take more than one dose in 24 hours.
• Sexual stimulation is required for sildenafil to work.
• Do not take more than the prescribed strength.

Sildenafil may take longer to work when taken with a large or high-fat meal. Avoid excessive alcohol because it can make it more difficult to achieve an erection and may increase the risk of side effects.

What strength should I take?

The usual starting dose for many men is 50mg. Depending on effectiveness, tolerability and your medical history, the prescriber may recommend 25mg or 100mg.

Do not increase the dose without advice from your prescriber.

Who should not take Sildenafil?

Do not take sildenafil if you:

• Take nitrate medicines for chest pain or angina, including glyceryl trinitrate.
• Use recreational drugs known as poppers, such as amyl nitrite.
• Take riociguat for pulmonary hypertension.
• Are allergic to sildenafil or another ingredient in the tablets.
• Have been advised to avoid sexual activity because of a serious heart condition.
• Have severe heart or liver problems.
• Have recently had a heart attack or stroke.
• Have very low blood pressure.
• Have previously experienced vision loss caused by non-arteritic anterior ischaemic optic neuropathy.

Your prescriber will assess your medical history and current medicines before approving treatment.

Important safety information

Tell your prescriber if you have:

• Heart disease or an irregular heartbeat.
• High or low blood pressure.
• Liver or kidney problems.
• Sickle cell anaemia, leukaemia or multiple myeloma.
• A physical condition affecting the shape of the penis.
• A stomach ulcer or bleeding disorder.
• An eye condition or previous sudden loss of vision.
• Another condition that could make sexual activity unsafe.

Tell the prescriber about all medicines, supplements and recreational drugs you use. Sildenafil can interact with several medicines, particularly nitrates, alpha-blockers, some antibiotics, antifungal medicines and treatments for HIV.

Do not combine sildenafil with Viagra or another erectile-dysfunction treatment unless specifically instructed by a clinician.

Possible side effects

Common side effects may include:

• Headache.
• Facial flushing.
• Indigestion.
• Feeling sick.
• A blocked or stuffy nose.
• Dizziness.
• Temporary visual disturbances, including blurred vision or changes in colour vision.

Do not drive or operate machinery if sildenafil causes dizziness or affects your vision.

When to seek urgent medical help

Seek urgent medical help if you experience:

• Chest pain during or after sexual activity.
• A prolonged or painful erection lasting more than four hours.
• Sudden loss or reduction of vision.
• Sudden loss or reduction of hearing.
• A seizure
• Swelling of the face, lips, tongue or throat.
• Difficulty breathing or another sign of a serious allergic reaction.

If you experience chest pain after taking sildenafil, do not use nitrate medicine for the pain. Seek urgent medical assistance and tell the healthcare professional when you took sildenafil.

Brand and packaging

The manufacturer, packaging, tablet colour and appearance may vary depending on availability. You will receive a UK-licensed generic sildenafil product in the strength approved by the prescriber.

Always read the patient information leaflet supplied with your medicine before taking it.