An OTC drug will help patients get treatment more quickly. Topicals tend to have a lower risk of side effects compared to oral medications, Dr. Avanafil Stendra. Pearlman says. Its effects might last longer if you have mild to moderate ED. It might work longer if you have mild to moderate erectile dysfunction. Common ones include: Flushing of the skin.Sildenafil (Viagra). This medicine works best when you take it on an empty stomach an hour before sex. The body takes longer to absorb it after a high-fat meal or alcohol. Its effects often last for 4 to 5 hours. It might work longer if you have mild to moderate erectile dysfunction. Vardenafil. Do you need a prescription for Viagra alternatives? Yes, if you are considering erectile dysfunction medications similar to Viagra — like Cialis, generic Viagra, and generic Cialis — it. Drug Images What is Viagra? Viagra is a brand-name prescription drug that’s approved to treat erectile dysfunction (ED). With ED, you’re unable to have or maintain an erection. Viagra is.