The active ingredient, sildenafil, inhibits the substances in the body that reduce an erection. In addition, the drug also relaxes the blood vessels in the penis, making it easier for blood to flow to the penis when a man is aroused. So you do not just get an erection when you take kamagra, sexual arousal is required. Thanks to the taking of Kamagra, the erection can be maintained for longer. Sometimes up to 6 o'clock. However, doctors rarely prescribe it because of its many side effects.