Cost. Pregnancy. Birth control needs. Breastfeeding. For professionals. Drug Images. What is Viagra? Viagra is a brand-name prescription drug that’s approved to treat erectile .They enhance the effects of a chemical the body makes that relaxes muscles in the penis, called nitric oxide. Sildenafil comes as a tablet and suspension liquid to take by mouth. Viagra can be taken as long as four hours or as little as 30 minutes before sex. If it is not treated right away, priapism can permanently damage your penis sudden vision loss in one or both eyes. Make sure you have discussed any other medications you are currently taking or plan to take before starting sildenafil with your doctor and pharmacist. Cialis lasts longer.Cost: If the price for branded Viagra is outside of your budget, Lemonaid’s $2 sildenafil pills are some of the lowest priced Viagra alternatives that we’ve found. Product details Usage: take. Drug Images. What is Viagra? If you have erectile dysfunction (ED), your doctor may recommend that you take Viagra. It’s a prescription drug that’s used in adult males* with .  · The highest recommended Viagra dose for treating erectile dysfunction (ED) is mg per day, according to the drug’s manufacturer. Doses of mg or mg would be considered off-label use.Your doctor or other health care professional can recommend one for you based on these factors, other health conditions you have and any other medicines you take. Daily doses are often between 2. Erectile dysfunction is a condition where the penis does not harden and expand when a man is sexually excited, or when he cannot keep an erection. Its effects might last longer if you have mild to moderate ED. Before starting, stopping, or changing any medications while taking sildenafil, please get the advice of your doctor or pharmacist. These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly. Sildenafil is in a class of medications called phosphodiesterase PDE inhibitors.