Some of the medicines used for self-injections are alprostadil Caverject, Edex and phentolamine OraVerse. There are two main types of implants. Oral medicine for ED might not work or might be dangerous if you already take: Nitrate medicines often prescribed for chest pain, also called angina. Severe liver disease. They keep the penis firm but bendable.Because it improves blood flow to the penis, Viagra (sildenafil citrate) treats erectile dysfunction (ED) effectively. But now that the “little blue pill” is more accessible, some . You should also avoid products you can buy online without a prescription that claim either to be generic forms of sildenafil or to contain sildenafil. (Sildenafil is the active drug. Viagra alternatives range from medical options like Cialis and Levitra to natural methods like acupuncture and even therapy. We break them all down here. When you think of erectile.