Tadalafil treats PAH by relaxing the blood vessels in the lungs to allow blood to flow more easily. Tadalafil is in a class of medications called phosphodiesterase PDE inhibitors. Before taking tadalafil, tell your doctor and pharmacist if you are allergic to tadalafil, any other medications, or any of the ingredients in tadalafil tablets. It may be taken with or without food. If you are taking tadalafil for erectile dysfunction, your doctor will probably start you on an average dose of tadalafil and increase or decrease your dose depending on your response to the medication. Your doctor will probably tell you not to take tadalafil if you are taking street drugs containing nitrates.The lowest price on for generic Cialis (tadalafil) 20 mg is $ per tablet for 88 tablets at PharmacyChecker-accredited online pharmacies. Lowest U.S. Pharmacy Coupon Price: $ per tablet for 90 tablets. Sign . VAT 20%: $. 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 . See all coupons See all tadalafil cialis prices. 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. The 20 mg tablet is the highest strength and is.