These medicines all work well for ED. Avanafil Stendra. What side effects can this medication cause? John’s wort. Severe liver disease. You should only be treated with one of these products at a time.Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Sildenafil (Liqrev, Revatio) is used to improve the ability to exercise in . Sildenafil (Viagra). This medicine works best when you take it on an empty stomach an hour before sex. The body takes longer to absorb it after a high-fat meal or . Sildenafil (Viagra brand) increases blood flow to the penis following sexual stimulation. It does this by blocking the enzyme responsible for the breakdown of cGMP. .
