Make sure you have discussed any other medications you are currently taking or plan to take before starting sildenafil with your doctor and pharmacist. These medicines prevent an enzyme called phosphodiesterase type-5 from working too quickly. If you ever need emergency medical treatment for a heart problem, the healthcare providers who treat you will need to know when you last took sildenafil. Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medicine. Other uses for this medicine This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information. Sildenafil belongs to a group of medicines called phosphodiesterase 5 PDE5 inhibitors.Drugs & Medications Sildenafil Tablet Sildenafil Tablet – Uses, Side Effects, and More Common Brand (S): Viagra Generic Name (S): sildenafil Uses Sildenafil is used to treat male. The normal dose when starting Viagra is 50 mg, as needed. The maximum dose of Viagra is mg each day. Doses above the maximum dose, such as mg per day, will increase the risk of side. This drug is more popular than comparable drugs. It is available in generic and brand versions. Generic sildenafil is covered by most Medicare and insurance plans, but some pharmacy coupons or cash prices may be lower. Compare PDE5 inhibitors.