If you have an erection that lasts more than 4 hours, get medical help right away. Medicines that block an enzyme called CYP3A4. Some platforms have a digital pharmacy that ships the medication to your home, while others send an electronic prescription to your local pharmacy. 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. Severe liver disease. Online ED consultations offer privacy, convenience, and affordability while allowing you to quickly get the medications you need—the same day, with some services. Contact your medical provider if you experience any side effects during treatment.Viagra (sildenafil) as low as. $ View other PDE5 Inhibitors. 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. Get a Savings Card Sign up for a Savings Card and, if eligible, you may save 50% on up to 12 prescriptions of brand-name VIAGRA per year.* * Terms and conditions apply. Check Your Pills Check your pills to be sure they’re brand-name VIAGRA—not the generic. Oral medicines for ED usually work well and cause few side effects. The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors.