If you have an erection that lasts more than 4 hours, get medical help right away. All PDE5 inhibitors, including Viagra and Cialis, require a valid prescription regardless of the pharmacy or provider. Erectile dysfunction medications require a prescription from a licensed provider. It may be difficult to remain firm despite wanting to have sex. 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. The generic versions are just as effective and much less expensive.Text Download 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. If you take Viagra long term, you may be able to lower its cost in the following ways. Getting a 3-month supply You may be able to get a day supply of Viagra. Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in men. It is also used to treat pulmonary arterial hypertension, a serious heart and lung condition. This drug is more popular than comparable drugs. It is available in generic and brand versions.