Never purchase ED medications from a site or service that doesn’t require a prescription and medical documentation. Generic vs. It may be difficult to remain firm despite wanting to have sex. Cialis 20 mg tablet is not recommended to use in women. Common side effects include headache, facial flushing, indigestion, and dizziness. However, all medications come with risks. You’ll also need to fill out a medical questionnaire with answers about your medical history, current medications, and lifestyle habits.Cialis is a popular ED medication. Find out everything you need to know about this doctor-prescribed medication including usage, effectiveness, and safety considerations. Cialis (tadalafil) is a prescription tablet used for erectile dysfunction and benign prostatic hyperplasia. Learn about dosage, side effects, and more. Generic Cialis, or Tadalafil, is available in several doses in tablet form: milligrams (mg), 5 mg, 10 mg, and 20 mg. Depending on the dose for ED, you can use it as needed .