Both 50 mg and 100 mg of sildenafil therapy increased the ED patients’ average monthly frequency of sexual intercourse, improved erectile function state in self-assessment, and elevated sexual satisfaction and enjoyment. Viagra lasts for up to 4 hours. The average time of onset is 60 minutes. The effects vary for each individual. Learn more about how long Viagra lasts here. In a large study on more than 8000 patients, 82% reported improvements in their erections after taking 100mg sildenafil. Although this demonstrates a very high success rate, it shows how the treatment doesn’t always work for everyone. The question is: why? This study demonstrates that, in the majority of these patients with ED, sildenafil remains clinically active 12 hours after administration. Larger studies may be necessary to confirm and clarify the therapeutic window of sildenafil.
