Tadalafil and Cialis are medically equivalent but Tadalafil is available at a much lower cost. Available on boots. Tell your healthcare provider that you take Cialis. Cialis lasts longer. Share this article. You could get dizzy, faint or have a heart attack or stroke. What dose should you take?The normal dosage of Cialis for occasional use in treating ED is 10 mg taken before sexual activity. If you have side effects with the mg dose, your doctor may prescribe a 5-mg dose. If the Cialis (branded Tadalafil) Cialis is a reliable, branded ED treatment that lasts up to 36hrs. Can be taken with food. Works in 30mins, lasts up to 36hrs. Works for 80% of men. 10mg 20mg. 4 tablets. Out of stock. 8 tablets. 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.