If it is not treated right away, priapism can permanently damage your penis sudden vision loss in one or both eyes. During 3 to 6 months of double-blind treatment or longer-term 1 year , open-label studies, few patients withdrew from active treatment for any reason, including lack of effectiveness. Aspirin was originally marketed by drug company Bayer in as a painkiller, but was first repositioned in the s, at low doses only, as an antiplatelet aggregation drug, and is still widely used today to prevent cardiovascular events. 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. In these studies, involving about patients, analyses of patient diaries showed no effect of VIAGRA on rates of attempted intercourse about 2 per week , but there was clear treatment-related improvement in sexual function: per patient weekly success rates averaged 1. How should this medicine be used? Tell your doctor if sildenafil is not working well or if you are experiencing side effects.Email With the VIAGRA Savings Card, eligible patients may save 50% on up to 12 prescriptions of brand-name VIAGRA per year.* *Eligible patients could save up to $4, a year. Savings Card only works on brand-name VIAGRA. Terms and conditions apply. LEARN MORE ABOUT VIAGRA Taking VIAGRA How to Get Brand-Name VIAGRA . Vision changes. Muscle pain. But there are some differences. With Viagra, there is a higher risk of vision changes than with Cialis. Among people who take Viagra or sildenafil, 3% get blue vision that lasts a few hours. On the other hand, Cialis has a slightly higher risk of muscle pain than Viagra and vardenafil. Viagra is available as the generic drug sildenafil. A generic drug is considered as safe and effective as the original drug. And generics tend to cost less than brand-name drugs.