Sildenafil how long sildenafil may also be used for other purposes not listed above. In case you notice any side effects not listed above, contact your doctor or pharmacist. 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.