Ask your healthcare professional how you should dispose of any medicine you do not use. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine. Click here for an email preview. From Mayo Clinic to your inbox Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. If you are taking sildenafil to treat erectile dysfunction, you should know that it does not cure erectile dysfunction or increase sexual desire. · Generic name: sildenafil (oral) [ sil-DEN-a-fil ] Brand names: Revatio, Viagra Drug classes: Agents for pulmonary hypertension, Impotence agents. Medically reviewed by Kaci Durbin, MD. Last updated on Uses; Warnings; Before taking; Dosage; Side effects; Interactions; FAQ; What is sildenafil? Generic: Sildenafil. Form: oral tablet; Strengths: 25 mg, 50 mg, mg; Brand: Viagra. Form: oral tablet; Strengths: 25 mg, 50 mg, mg; Adult dosage (ages 18–64 years). In combination with sexual stimulation, sildenafil works by increasing blood flow to the penis to help a man get and keep an drug does not protect against sexually transmitted.