Common side effects include headache, facial flushing, indigestion, and dizziness. Tadalafil is also sometimes taken once a day every day without regard to timing of sexual activity. Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient. It may take some time and trial and error to determine the best dosage as well as the best time to take Cialis. Dosing is as follows: As needed for ED: 5 to 20 mg by mouth as a one-time dose, with a maximum of one dose in 24 hours. Tadalafil may cause side effects.Cialis (tadalafil) is a popular medication used to treat erectile dysfunction. It’s available in tablets ranging from mg to 20mg. It can cost more than $ for a month’s supply, depending on the dosage you need and the pharmacy you visit. You can save more than 90% on the average retail price at certain pharmacies by using a GoodRx coupon. Cialis (tadalafil) and Viagra are both used for erectile dysfunction, but there are a couple of distinctions between the two. Unlike Viagra, low-dose tadalafil can be taken on a daily . A manufacturer coupon or copay card is not available for Cialis. However, GoodRx discounts are available to help make it more affordable. Tadalafil, the generic version of .