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. This medicine works best when you take it on an empty stomach an hour before sex. Rarely reported side effects include: an erection that will not go away priapism. In some patients, the use of VIAGRA with alpha-blockers can lead to a drop in blood pressure or to fainting medicines called HIV protease inhibitors, such as ritonavir Norvir , indinavir sulfate Crixivan , saquinavir Fortovase or Invirase , or atazanavir sulfate Reyataz some types of oral antifungal medicines, such as ketoconazole Nizoral and itraconazole Sporanox some types of antibiotics, such as clarithromycin Biaxin , telithromycin Ketek , or erythromycin other medicines that treat high blood pressure other medicines or treatments for ED VIAGRA contains sildenafil, which is the same medicine found in another drug called REVATIO. These are commonly prescribed for an enlarged prostate or male pattern baldness. Recent heart or blood vessel problems. The most common side effects of VIAGRA: headache; flushing; upset stomach; abnormal vision, such as changes in color vision such as having a blue color tinge and blurred vision; stuffy or runny nose; back pain; muscle pain; nausea; dizziness; rash.Cost Overdose Ask your doctor Q&A Drug Images What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. It’s a . Clinically proven to treat men with erectile dysfunction (ED) Ongoing commitment to product quality and safety monitoring Learn More IF YOU CHOOSE BRAND-NAME VIAGRA, . Drug Facts Common Brands Viagra Drug Class PDE-5 inhibitor Controlled Substance Classification Not a controlled medication Generic Status Lower-cost generic .