Medicine for good erection sildenafil affects the response to sexual stimulation. It acts by enhancing smooth muscle relaxation using nitric oxide, a chemical that is normally released in response to sexual stimulation. This smooth muscle relaxation allows increased blood flow into certain areas of the penis, which leads to an erection. 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. It is preferable not to use Cialis with grapefruit juice, alcoholic beverages, tobacco. If you smoke tobacco and take Cialis concomitantly this may lead to a condition called NAION (sudden optic nerve-related vision loss). Inform your doctor before to take. Cialis if you have abnormal penis, including curved penis and birth defects of the penis, had coronary artery disease, arrhythmia, angina, heart attack or heart failure, hypo- or hypertension, bleeding, stomach ulcers, diabetes, hyperlipidemia (excess of lipids in the blood), sickle-cell anaemia, liver or kidney failure in history.