Viagra is an effective drug for treating male erectile dysfunction, but it targets sexual performance, not sexual arousal. There is limited evidence that Viagra may be beneficial for women with sexual dysfunction, but the trials have been small and the results .Sexual activity may be a strain on your heart, especially if you have heart disease. Oral ED medicines might not work or might be dangerous if you also take any of the following: Nitrate medicines. Food and Drug Administration has approved fifteen drug manufacturers to market generic sildenafil in the United States. Numerous sites on the Internet offer Viagra for sale after an “online consultation”, often a simple questionnaire. Some medications should not be taken with sildenafil. If you become pregnant while taking sildenafil, call your doctor.Sildenafil (Liqrev, Revatio) is used to improve the ability to exercise in adults (Liqrev, Revatio) and children 1 year of age and older (Revatio) with pulmonary arterial . Viagra works by increasing blood flow to your penis, which helps you have and keep an erection. But this drug only works if you’re sexually aroused. Viagra comes as tablets . Viagra is an effective drug for treating male erectile dysfunction, but it targets sexual performance, not sexual arousal. There is limited evidence that Viagra may be beneficial for women with sexual dysfunction, but the trials have been small and the results .The patent was published in and expired in Do not take a double dose to make up for a missed one. It lasts 4 to 5 hours, or 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. If you are taking sildenafil to treat PAH, you will probably take sildenafil three times a day with or without food.