There is also the option to take Cialis as needed. The major circulating metabolite results from N-desmethylation of sildenafil, and is itself further metabolized. Privacy: Confirm that your personal data and payment details are confidential. As in the other titration studies, patients were started on 50 mg and allowed to adjust the dose up to mg or down to 25 mg of VIAGRA; all patients, however, were receiving 50 mg or mg at the end of the study. The most common symptoms of erectile dysfunction include difficulty achieving or maintaining an erection and reduced sexual desire. However, if you’d feel more comfortable talking with a healthcare provider virtually rather than in person, you can consider requesting an online ED prescription instead. This can happen if you are sick with fever, diarrhea, or vomiting; sweat a lot; or do not drink enough liquids.20 mg sildenafil oral tablet from $ for 10 tablets 25 mg sildenafil oral tablet from $ for 30 tablets 50 mg sildenafil oral tablet from $ for 15 tablets mg . Examples of Viagra’s more commonly reported side effects include: headache. flushing (temporary warmth, redness, or deepening of skin color) stuffy nose. indigestion (upset stomach) mild vision. 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 adults (Liqrev, Revatio) and children 1 year of age and older (Revatio) with pulmonary arterial hypertension (PAH; high blood pressure in the vessels carrying blood to the .