Tadalafil is its active ingredient and is available as a generic drug. Talk to your doctor about which dosing schedule is right for you. Indigestion and heartburn. In clinical trials, 68 percent to 77 percent of men with erectile dysfunction who used Cialis at a 10mg dosage were able to have penetrative sex with their partner, compared to 46 percent to 55 percent of men who were given a non-therapeutic placebo. Why is the dosage important? Cialis 5mg Cialis is available as a 5mg tablet.Tadalafil is sometimes taken as needed, usually at least 30 minutes before sexual activity and not more often than once every 24 hours. Your doctor will help you decide the best time for you to take tadalafil before sexual activity. Tadalafil is also sometimes taken once a day every day without regard to timing of sexual activity. The cost for tadalafil oral tablet 5 mg is around $27 for a supply of 90 tablets, depending on the pharmacy you visit. Quoted prices are for cash-paying customers and are not valid . Commonly prescribed doses: Tadalafil is taken as needed, with 10mg as a single dose. Take it 30 minutes before sexual activity. Only take Tadalafil once a day. Take mg of Tadalafil once a day, at the same time every day. Ask your doctor to adjust your dose as needed. This may mean increasing your dose to 20mg or decreasing it to 5mg.