People with heart conditions should never take ED medications without consulting a doctor. It lasts 4 to 5 hours, or longer if you have mild to moderate ED. The four main medicines taken by mouth for erectile dysfunction are: Avanafil Stendra. Read our editorial process. While each PDE5 inhibitor differs slightly, they’re very similar in treating erectile dysfunction. Other warning signs of an unsafe online pharmacy include outdated medication, no customer service, or suspiciously low prices.AdWith RexMD you’re saving time and money with our Viagra delivery. Get started now. Reliable E.D. meds prescribed by real doctors. Get your free & private online visit todayFree Shipping · Discreet Packaging · Real Doctors · Personalized PlanTypes: Sertraline · MEDICATIONS · Testosterone · Genital Herpes. 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 prescription . The recommended dosage of Viagra for erectile dysfunction (ED) is 50 mg, taken as needed about 1 hour before sexual activity. You can take it 30 minutes to 4 hours before .