Kamagra can help improve your libido and your ability to get and keep an erection. It has sildenafil citrate, which is the active ingredient. This increases the flow of blood to your penis, which helps you get and keep an erection. It has been proven that the drug does not cause an erection on its own. Kamagra works when the erogenous zone is stimulated, which helps men control when an erection starts. How Kamagra works Kamagra's active ingredient, sildenafil citrate, is a potent phosphodiesterase-5 (PDE-5) inhibitor that works on the erectile tissue of the penis to increase blood flow and produce an erection, which is the natural response to sexual stimulation. On average, it takes about 30 minutes to get an erection, and the effect lasts between 4 and 6 hours, depending on how much you take and how fast your body breaks down the drug.