Viagra 25mg, 50mg or 100mg

Viagra contains the active substance sildenafil which belongs to a group of medicines called phosphodiesterase type 5 (PDE 5) inhibitors. It works by helping to relax the blood vessels in your penis, allowing blood to flow into your penis when you get sexually excited. In most men Viagra works within an hour and effects last for about four hours - this doesn't mean the erection lasts for four hours, rather that an erection can be produced for up to four hours after taking a tablet.

Do not take Viagra:

• if you are allergic (hypersensitive) to sildenafil or any of the other ingredients listed in the patient information leaflet
• if you are taking medicines called nitrates (often given for relief of angina pectoris (or chest pain) - the combination may lead to a dangerous fall in your blood pressure
• if you are using any of the medicines known as nitric oxide donors such as amyl nitrite (poppers), as the combination may also lead to a dangerous fall in your blood pressure
• if you are taking riociguat - a drug used to treat pulmonary arterial hypertension (i.e. high blood pressure in the lungs) and chronic thromboembolic pulmonary hypertension (i.e. high blood pressure in the lungs secondary to blood clots)
• if you have a severe heart or liver problem
• if you have recently had a stroke or a heart attack, or if you have low blood pressure
• if you have certain rare inherited eye diseases (such as retinitis pigmentosa)
• if you have ever had loss of vision due to non-arteritic anterior ischaemic optic neuropathy (NAION)

Viagra is not indicated for use by women

Do not take Viagra with other medicines unless your doctor tells you that you can. You must tell your doctor if you are taking, have recently taken or might take other medicines, in particular:

• medicines used to treat chest pain - in the event of a medical emergency, you should tell your doctor, pharmacist or nurse that you have taken Viagra and when you did
• medicines called nitrates - the combination of these medicines may lead to a dangerous fall in your blood pressure
• medicines known as nitric oxide donors such as amyl nitrite (“poppers”) - the combination may also lead to a dangerous fall in your blood pressure
• riociguat
• protease inhibitors, such as for the treatment of HIV

• headache
• nausea
• facial flushing
• hot flush
• indigestion
• colour tinge to vision
• blurred vision
• visual disturbance
• stuffy nose
• dizziness

Sildenafil is also available and is the generic form of Viagra. Other ED medications include Cialis, Levitra and Spedra. Alternative treatments to ED medication include treating underlying physical or psychological causes, undergoing lifestyle changes, vacuum devices and surgical intervention.