Kamagra is a popular medication for erectile dysfunction that contains sildenafil citrate. It takes effect within 30-60 minutes when taken orally up to one hour before sexual activity. The recommended dose is 50mg, or 25mg for those over 65 or with liver or kidney issues. Side effects can include headaches, flushing and visual changes. Kamagra is available online through medical questionnaires and physician review at Exact Pharma, which does not have additional prescription or shipping costs beyond the listed product price.