Kamagra 100 mg oral jelly should be placed under the tongue at least 15 minutes before sexual intercourse as it takes less than an hour for the medicine to activate and show its effectiveness. Many doctors recommend using Kamagra Oral Jelly once a day and not using it as a regular medicine if the patient does not have sexual intercourse on a daily basis. Kamagra jelly works by increasing the blood flow in the penis to achieve a harder erection in men and helps them enjoy their sexual activity.