It’s available in 25 mg, 50 mg, and mg tablets and lasts up to 18 hours. It’s available in 50 mg, mg, and mg tablets. Other warning signs of an unsafe online pharmacy include outdated medication, no customer service, or suspiciously low prices. What should I do if I forget a dose? 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. Both options require valid medical documentation, but some online services only require a health questionnaire to be filled out and reviewed for approval—meaning no face-to-face video interaction is needed. You should only be treated with one of these products at a time.Generic Viagra (sildenafil) is available as a , , , and milligram (mg) pill and in liquid form. It’s meant to be taken as needed — about an hour before sex — but shouldn’t be. The discount plan organization is Hippo Network LLC, One World Trade Center, Suite New York, NY , , help@, . Best Low Cost: GoodRx Fastest Delivery: Blink Health: Sesame Sign Up Now Key Specs Cost: Consultation prices vary based on the prescriber; $5 generic prescriptions Medical .