Read more on male sexual health on the Sexual Health Australia site. Take both tablets one after the other. What should I do if I missed a dose of Cialis Tadalafil? Conclusion Purchasing Cialis online offers numerous advantages, from convenience to cost-effectiveness. Some common side effects include headaches, back pain, nasal congestion, or flushing. The drug is approved for use in adults. How Effective Is Cialis? · Cialis is a brand-name prescription medication. It’s FDA-approved to treat the following in males:* erectile dysfunction (ED), a condition in which you can’t get or keep an erection symptoms of. $. Total: $. Contact. After taking a single tablet, some of the active ingredient of Cialis remains in your body for more than 2 days. Cialis is a brand of tadalafil, one of the most popular medications to treat erectile dysfunction (ED).It was first approved in Cialis and generic tadalafil are available in four different strengths— mg, 5 mg, 10 mg and 20 mg—but which one should you take? If you’ve never tried Cialis before, your doctor will likely start you on a low dose, like mg or 5 mg.