If you drink a large amount of alcohol more than five glasses of wine or five shots of whiskey while you are taking tadalafil you are more likely to experience certain side effects of tadalafil such as dizziness, headache, fast heartbeat, and low blood pressure. How should this medicine be used? This increased blood flow can cause an erection. If you experience chest pain, dizziness, or nausea during sexual activity, call your doctor immediately or get emergency medical treatment, and avoid sexual activity until your doctor tells you otherwise. Tadalafil is in a class of medications called phosphodiesterase PDE inhibitors. Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medicine. What should I do if I forget a dose?Cialis: A prescription of 30 Cialis pills costs $ Tadalafil: 30 tadalafil pills are available for $ PlushCare also works with several health insurance providers. Tadalafil (Cialis) is used to treat erectile dysfunction (ED, impotence; inability to get or keep an erection), and the symptoms of benign prostatic hyperplasia (BPH; an enlarged prostate) which include difficulty urinating (hesitation, dribbling, weak stream, and incomplete bladder emptying), painful urination, and urinary frequency and urgency in adult men. milligrams (mg) 5 mg 10 mg 20 mg The cost for these different strengths depends on whether you have insurance, your individual plan coverage, and your .