Kidney disease that needs to be treated with dialysis. Topicals tend to have a lower risk of side effects compared to oral medications, Dr. Its effects often last for 4 to 5 hours. They enhance the effects of a chemical the body makes that relaxes muscles in the penis, called nitric oxide. As with sildenafil, a high-fat meal or alcohol keep the body from absorbing it as quickly. Avanafil Stendra. They’re often the first line of treatment for trouble getting or keeping an erection, called erectile dysfunction ED.Extra 15% off $30 sitewide with code SAVE15; Clip your mystery deal! BOGO 50% off select Walgreens health & wellness. Viagra vs. over-the-counter products. Many over-the-counter (OTC) products may be advertised to help with ED. Examples of these products include: dehydroepiandrosterone (DHEA) ginseng;. Is there an over-the-counter Viagra? Viagra is only available with a prescription in the United States, Canada, and most other countries. Viagra is sold under the generic name sildenafil.