Kidney disease that needs to be treated with dialysis. For example, you will be limited to a three-month supply. Your doctor or other health care professional can recommend one for you based on these factors, other health conditions you have and any other medicines you take. Medications that are not approved by the FDA may not be allowed. In addition, some prescription medications in the U.Generic name: sildenafil (oral) [ sil-DEN-a-fil ] Brand names: Revatio, Viagra Drug classes: Agents for pulmonary hypertension, Impotence agents. Medically reviewed by Kaci . Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes muscles . This original viagra works great. – Now, Generic viagra in Mexico is called “Maxifort” and it is a lot cheaper. -Now having a viagra in Tijuana (without a prescription) for US tourist is not legal.