The main component of Viagra is Sildenafil Citrate. Sildenafil Citrate affects the response to sexual stimulation. It acts by enhancing smooth muscle relaxation using nitric oxide, a chemical that is normally released in response to sexual stimulation. This smooth muscle relaxation allows increased blood flow into certain areas of the penis, which leads to an erection. Sildenafil Citrate is applied for the treatment of erectile dysfunction (impotence) in men and pulmonary arterial hypertension. Sildenafil Citrate may also be used for other purposes not listed above.

Usually, the recommended dose is 50 mg. It is taken approximately 0,5-1 hour before sexual activity. Do not take Viagra more than once a day. A high-fat meal may delay the time of the effect of this drug. Try not to eat grapefruit or drink grapefruit juice while you are being treated with Sildenafil Citrate.

Before you start taking Sildenafil Citrate, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. Aged people may be more sensitive to the side effects of the drug.

Viagra is contraindicated in patients taking another medicine to treat impotence or using a nitrate drug for chest pain or heart problems. This medicine should not be taken by women and children as well as in patients with a known hypersensitivity to any component of the tablet.

The most common side effects are:

• headache
• flushing
• heartburn
• stomach upset
• nasal stuffiness
• lightheadedness
• dizziness or diarrhoea.

A serious allergic reaction to this drug is very rare, but seek immediate medical help if it occurs. Many people using this medicine do not have serious side effects. In case you notice any side effects not listed above, contact your doctor or pharmacist.

This drug should not be used with nitrates and recreational drugs called "poppers" containing amyl or butyl nitrite; alpha-blocker medications; other medications for impotence; high blood pressure medicines, etc. Consult your doctor or pharmacist for more details.

Viagra is used as needed, so you are unlikely to be on a dosing schedule.

If you think you have used too much of this medicine seek emergency medical attention right away. The symptoms of overdose usually include chest pain, nausea, irregular heartbeat, and feeling light-headed or fainting.

Store your medicines at room temperature between 68-77 degrees F (20-25 degrees C) away from light and moisture. Do not store the drugs in the bathroom. Keep all drugs away from reach of children and pets.