Now, the Drug Enforcement Agency DEA has proposed new rules that will require an in-person visit for anything more than a day supply of controlled substances to be filled by an online pharmacy. Common ones include: Flushing of the skin. Without physical action to the penis, such as that occurring during sexual intercourse, sildenafil will not work to cause an erection. Rogue pharmacies are not licensed to sell in the United States and put you at risk of counterfeit or tainted drugs How Many Online Pharmacies Are There? 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. These drugs also have to be specially labeled, so many online pharmacy companies have already elected not to deliver them. Often, these are prescribed for chest pain called angina.Sildenafil is used to treat men who have erectile dysfunction (also called sexual impotence). Sildenafil belongs to a group of medicines called phosphodiesterase 5 (PDE5) . Oral medicines for ED usually work well and cause few side effects. The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil . Typical dosing for Sildenafil (Viagra) The typical dose is to take 50 mg of sildenafil (Viagra) by mouth, about 1 hour before sex, as needed. The maximum recommended .