If you are taking tadalafil for erectile dysfunction on a regular schedule, take the missed dose as soon as you remember it. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive. If you do not meet the NHS criteria for tadalafil, you may get a private prescription from a doctor. Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine. Swallow the tablet whole. · Cialis® also contains tadalafil. If you take too much tadalafil or take it together with these medicines, the chance for side effects will be higher. If you experience a prolonged erection for more than 4 hours or a painful erection for more than 6 hours, contact your doctor immediately. This condition may require prompt medical treatment to. MNT ‘s review. Lemonaid sells Cialis in these forms: Cialis: available in doses of 5, 10, and 20 mg, starting at $65 per tablet. Daily Cialis: 5 mg tablet with pricing starting from $50 per tablet. Tadalafil (Cialis) is a medicine used to treat erectile dysfunction (ED, also called impotence) and problems with urination caused by an enlarged prostate (benign prostatic hypertrophy or BPH). Tadalafil works by helping to relax the blood vessels in the penis, allowing blood to flow into the penis, and causing an erection.