Psychological factors like stress, depression, or anxiety can also contribute. Do not take vardenafil more than once a day. Generic versions of sildenafil, vardenafil and tadalafil are available. These include itraconazole Sporanox, Tolsura , ketoconazole Extina, Ketozole, others and ritonavir Norvir. Swallow several times as the tablet dissolves. What Are the Symptoms of Erectile Dysfunction? Using the ED medicines we prescribe puts you at greater risk of severe reactions such as extreme dizziness, fainting, heart attack, and stroke.This drug is less popular than comparable drugs. There are currently no generic alternatives to Staxyn. It is not covered by most Medicare and insurance plans, but manufacturer and . 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 (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. Cialis lasts up to 36 hours in the body, while Viagra lasts 4–6 hours in the body. Both are taken 30 minutes before sex. Cialis can cause limb pain, while Viagra can cause vision change, rash.