The ingredient that Kamagra claims to contain, sildenafil, is not effective at making you last longer in bed. No erectile dysfunction medicine, such as Viagra, is effective at making you last longer in bed. However, other medicines can be effective for this. The condition is called premature ejaculation - when you ejaculate too soon during sex.  One medicine used to treat premature ejaculation is Priligy. This is a legal and fully licensed drug that can be taken before sex to increase the time to ejaculation. An alternative treatment that can be used is EMLA cream, which is a numbing cream you can apply to the penis before sex.