Best Viagra Online.
Viagra (sildenafil) is a PDE5 inhibitor often prescribed for the most severe cases of erectile dysfunction caused by whatever reasons. Viagra remains efficient for up to 5 hours - and you can have sex during this time. However, it does not become efficient right away - you will have to wait at least half an hour before you can experience full effects of this medicine. There are a number of serious side effects that you need to report to your health care provider as soon as possible. These include fainting, rash, burning during urination, chest pain, painful and prolonged erection, loss of hearing or vision, blurred vision, lightheadedness, dizziness and ringing in the ears. The risk factors for developing sudden vision loss include being older than 50, being diagnosed with heart disease, diabetes, high blood pressure, heart disease or having high cholesterol.