This increased blood flow can cause an erection. Check the healthdirect’s medicines section for more information about tadalafil. Communicate with your partner and interact with them after you take Cialis to help the medication work. If you are taking tadalafil to treat erectile dysfunction, follow your doctor’s directions and the guidelines in this paragraph. Always discuss with your health care practitioner ALL of the medications you are taking prescription and over-the-counter that way, you can receive the best advice for your own situation.headache. indigestion. back pain. muscle pain. flushing. stuffy nose. Patients who get back pain and muscle aches usually get them 12 to 24 hours after taking Cialis and these usually go away by. The normal dosage of Cialis for occasional use in treating ED is 10 mg taken before sexual activity. If you have side effects with the mg dose, your doctor may prescribe a 5-mg dose. If the headache *. upset stomach. runny nose. back pain *. upper respiratory infection. heartburn *. muscle pain. For a list of side effects reported by people taking Cialis in clinical trials, including.