Erectile dysfunction is a condition where the penis does not harden and expand when a man is sexually excited, or when he cannot keep an erection. When did you first begin noticing sexual problems? Does your partner have any sexual problems? Medicines that you take by mouth are called oral medicines. What to expect from your doctor Your doctor is likely to ask you a number of questions. Sildenafil works on the PDE5 enzyme in the lungs to relax the blood vessels. Sildenafil belongs to a group of medicines called phosphodiesterase 5 PDE5 inhibitors.What’s What with All the ED Pills. Viagra. Still the leading brand in ED pills, Viagra should be taken at least an hour before sex and on an empty stomach. That makes it difficult to . Viagra; Descriptions. Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called . Best prices for generic viagra on the Internet! The safest way is to ask your physician to try an alternate prescription. Sildenafil 50mg Tablets are designed for men who are suffering from Erectile Dysfunction problems. Recall that it is necessary to strictly observe the rules for storing drugs in the refrigerator; some drugs cannot be frozen.