Strengths: 25 mg, 50 mg, mg; Brand: Viagra. Form: oral tablet; Strengths: 25 mg, 50 mg, mg; Adult dosage (ages 18–64 years) Typical dosage: 50 mg, taken as needed about 1 hour before.If you are taking sildenafil for erectile dysfunction, you are unlikely to miss a dose since this medication is taken as needed, not on a regular dosing schedule. Keep from freezing. Side Effects Along with its needed effects, a medicine may cause some unwanted effects. Sildenafil may cause side effects. Sildenafil for pulmonary hypertension can also be known by the brand names Revatio and Grandipam. Check with your doctor immediately if any of the following side effects occur: Less common burning feeling in the chest or stomach burning, crawling, itching, numbness, prickling, “pins and needles”, or tingling feelings cloudy or bloody urine. Your doctor may adjust your dose as needed and tolerated.Drug Images Viagra treats erectile dysfunction (ED) in adults. It’s usually taken about 1 hour before sexual activity. Below, you’ll find information about recommended dosages . 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 . Generic Viagra (sildenafil) is an alternative to the branded Viagra drug that can be used for treating erectile dysfunction (ED). It’s now sold by many manufacturers, including online.Ask your healthcare professional how you should dispose of any medicine you do not use. John’s wort. If your dose is different, do not change it unless your doctor tells you to do so. Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Side Effects Along with its needed effects, a medicine may cause some unwanted effects. Sildenafil Viagra is used to treat erectile dysfunction impotence; inability to get or keep an erection in men.