Kamagra Oral Jelly only works in combination with sexual stimulation. It becomes effective within 20 to 60 minutes and, on average, it can last up to 4 - 6 hours, but many patients have reported longer periods of time. Kamagra Oral Jelly 100mg is used to treat erectile dysfunction (impotence) in men, which is inability to achieve or maintain a hard erect penis suitable for sexual activity, due to insufficient blood flow into the penis