What is Manforce 50 used for? Manforce 50 tablet 9's is used to treat erectile dysfunction (impotence) in adult men. Manforce 50 Tablet 9's works by relaxing the blood vessels in the penis, thereby allows the blood flow into the penis when the person is sexually excited. How long does Manforce 100 mg last? The amount of time Manforce 100 mg Tablet takes to work varies from person to person, but it normally takes between half an hour and one hour. However, Manforce 100 mg Tablet may take longer to start working if you take it with a heavy meal. Its effect may last for about 3-4 hours.18-