The drug kamagra is used to treat erectile dysfunction (ED), a condition in which a man finds it difficult to get or keep an erection strong enough for sexual activity. The active component of it is sildenafil citrate, a medication that is categorized as a phosphodiesterase type 5 (PDE-5) inhibitor. Slackening of the blood vessels: Nitric oxide, a substance released by the body in response to sexual stimulation, causes the smooth muscles in the penile blood vessels to relax. The penile tissues receive more blood flow as a result of this relaxation.