For males aged 18 and above, Viagra may serve as an effective remedy for erectile dysfunction (ED). However, Viagra is not advisable if you have any of the following pre-existing conditions: 

• an allergy to Viagra or sildenafil 

• low blood pressure 

• a heart or liver condition 

• recent experience of a stroke or heart attack 

• a rare inherited eye disease known as retinitis pigmentosa

Viagra and Blood Pressure: The active ingredient in Viagra, sildenafil, is occasionally utilised in treating pulmonary hypertension (high blood pressure in the lungs). This is achieved by the dilation of blood vessels, which is also the mechanism behind its effectiveness in treating erectile dysfunction. If you have low blood pressure or are on medications to lower it, consulting with a doctor before taking Viagra is recommended. 

Even in the absence of pre-existing conditions, there are instances where Viagra should be avoided. Refrain from taking Viagra if you: 

• are using other medications for erectile dysfunction (ED) 

• have sickle cell anaemia 

• have a deformity of the penis 

• are taking nitrates for chest pain 

• have specific eye conditions, such as non-arteritic anterior ischemic optic neuropathy (NAION) 

• are taking nicorandil or nitrates, such as GTN spray or isosorbide mononitrate tablets to treat angina 

Viagra is not authorised for use by women and is exclusively licensed for male use in the UK.