Your doctor or other health care professional can recommend one for you based on these factors, other health conditions you have and any other medicines you take. From Mayo Clinic to your inbox Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. By controlling the enzyme, tadalafil helps to maintain an erection after the penis is stroked by increasing blood flow to the penis. Will Cialis be prescription or OTC over-the-counter? The safety and effectiveness of Cialis when used with other treatments for impotence has not been studied.Brand Cialis Generic Tadalafil No data Form Bottle Box Disp Pack Tablet No data Dosage mg 5mg 10mg 20mg No data Quantity 5 6 10 15 30 90 No data. Cialis comes in several different strengths, including: milligrams (mg) 5 mg. 10 mg. 20 mg. The cost for these different strengths depends on whether you have insurance, your individual plan. Avoid or lower your alcohol consumption when taking tadalafil (Cialis). You should never take tadalafil (Cialis) when taking nitrate medication for chest (including prescribed and over-the-counter medications, vitamins, and dietary or herbal supplements) that you are currently taking. please call or email us at or ada.