What Is Sildenafil Used For and Where Can You Buy It?

Sildenafil is best known as a treatment for erectile dysfunction. It is the active ingredient in Viagra and many generic alternatives. This article explains what sildenafil is, how it works, the conditions it is used to treat and where it can be obtained in the UK.

What is sildenafil?

Sildenafil, also known as sildenafil citrate, belongs to a group of medicines called PDE5 inhibitors. It is mainly used to treat erectile dysfunction, but it is also prescribed in different doses for pulmonary arterial hypertension.

Sildenafil citrate was developed by the US pharmaceutical company Pfizer. It was initially investigated as a treatment for chest pain, but researchers noticed its effect on erections. In 1998 it was approved as an oral treatment for erectile dysfunction.

Sildenafil was later approved for pulmonary arterial hypertension. Products and doses used for that condition are different from those used for ED and should only be taken under specialist supervision.

In the UK, certain sildenafil products for erectile dysfunction can be supplied by a pharmacist after a suitability assessment. Prescription versions are also available. Treatment for pulmonary hypertension is prescribed and monitored by a specialist.

What is erectile dysfunction?

Erectile dysfunction is the persistent or recurring inability to achieve or maintain an erection firm enough for sex. The causes can be broadly divided into:

psychological factors, such as stress, trauma, depression or performance anxiety
physical factors, such as cardiovascular disease, diabetes, hormonal problems, nerve damage or medication.

Erectile dysfunction becomes more common with age, but it can affect younger men as well. It is often treatable, and sildenafil is one of several available options.

What is pulmonary hypertension?

Pulmonary hypertension is high blood pressure in the blood vessels that supply the lungs. Symptoms may include:

shortness of breath
low energy
fatigue

Sildenafil can help by relaxing blood vessels in the lungs and reducing the strain on the heart. This use requires specialist diagnosis and monitoring.

How sildenafil works

Sildenafil blocks the PDE5 enzyme and allows levels of cGMP to remain higher in the erectile tissue. This helps smooth muscle relax and increases blood flow into the penis during sexual stimulation.

The same type of blood-vessel relaxation explains why sildenafil can be useful in pulmonary arterial hypertension.

Sildenafil works for erectile dysfunction only when there is sexual stimulation. It does not produce an automatic erection and is not an aphrodisiac.

Who should not take sildenafil?

Do not take sildenafil with nitrates used for chest pain or recreational nitrites known as “poppers”. The combination can cause a dangerous fall in blood pressure.

Speak to a doctor or pharmacist before using sildenafil if you have a serious heart or liver condition, have recently had a heart attack or stroke, have very low blood pressure or an inherited eye disease, or if sexual activity may be unsafe for you.

Extra caution may be needed if you have:

cardiovascular disease
a penile deformity such as Peyronie’s disease
a condition that increases the risk of a prolonged erection
significant liver or kidney problems.

Sildenafil can interact with other medicines. Tell the healthcare professional assessing you about all prescription treatments, over-the-counter products, supplements and herbal remedies.

Sildenafil for erectile dysfunction is intended for adult men. Sildenafil used for pulmonary hypertension may be prescribed to adults or children under specialist care, according to the specific product and dose.

Sildenafil side effects

Common side effects include headache, flushing, indigestion, a blocked nose, nausea and dizziness. Some men notice temporary visual changes. Diarrhoea, muscle pain and skin rash may also occur.

Seek urgent medical help if you develop chest pain, fainting, a severe allergic reaction, sudden loss of vision or hearing, or priapism—an erection lasting longer than four hours.

Do not drive, cycle or operate machinery if sildenafil makes you dizzy or affects your vision.

Lifestyle changes may improve erectile function and general health:

stop smoking
limit alcohol
eat a balanced diet
exercise regularly.

Medicines that contain sildenafil

The best-known sildenafil product is Viagra. Other products include:

Sildenafil products used for pulmonary arterial hypertension include Revatio and other specialist brands. Do not substitute one formulation for another without medical advice.

Recommended sildenafil dose

Sildenafil for ED is available as standard tablets, orodispersible products and, in some markets, chewable or liquid formulations.

A common starting dose is 50mg, taken around one hour before sexual activity. It may be increased to 100mg or reduced to 25mg according to response, side effects and medical advice. Do not take it more than once in 24 hours.

If you take more than recommended, contact a healthcare professional or NHS 111, particularly if you develop severe side effects.

How long does sildenafil last?

Sildenafil usually starts working within 30–60 minutes and reaches its strongest effect around an hour after taking it. Sexual stimulation is still required. Its useful window generally lasts around four to six hours, although the response varies.

A heavy, high-fat meal can delay the onset. Excessive alcohol may reduce your ability to achieve an erection and increase dizziness or low blood pressure.

Where can you buy sildenafil?

The price depends on the brand, strength and pack size. Branded Viagra is normally more expensive than generic sildenafil.

As a rough guide, a four-tablet pack of branded 50mg sildenafil may cost around £46, while a comparable generic pack may be available for approximately £20. Prices change, so check the current total including assessment and delivery charges.

Sildenafil can be obtained through high-street or online pharmacies. Online ordering may offer privacy, fast delivery and competitive prices. Use an established supplier with secure payment, clear contact details and an appropriate suitability assessment.