Kamagra 100 contains an ingredient called sildenafil which helps men to have an erection for a longer period of time. This sildenafil ingredient helps in relaxing the penile tissues of men. Kamagra 100 medicine works effectively when you take it 30 minutes before or 1 hour before intercourse. The effect of this medicine lasts for 4 to 6 hours. You can take this medicine before or after food. Take this medicine as per the doctor's advice.