Without physical action to the penis, such as that occurring during sexual intercourse, sildenafil will not work to cause an erection. If you have certain health conditions or are taking certain medications, your doctor may tell you to take sildenafil less often. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. If you are taking sildenafil to treat erectile dysfunction, you should know that it does not cure erectile dysfunction or increase sexual desire. Males between the ages of 30 and 65 would be eligible to buy four tablets after a consultation with a pharmacist.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 . Viagra – Uses, Side Effects, and More Generic Name (S): sildenafil Uses Sildenafil is used to treat male sexual function problems (impotence or erectile dysfunction-ED). Sildenafil (Viagra) is used to treat erectile dysfunction (impotence; inability to get or keep an erection) in men. Sildenafil (Liqrev, Revatio) is used to improve the ability to exercise in .