Imitrex without a prescription sildenafil may also be used for other purposes not listed above. Kamagra Oral Jelly is taken, as needed, approximately 1 hour before sexual activity. Do not take Kamagra Oral Jelly more than once a day. A high-fat meal may delay the time of the effect of this drug. Try not to eat grapefruit or drink grapefruit juice while you are being treated with Sildenafil.