It may be taken with or without food. Keep out of the reach of children. Some people buy tadalafil online without a prescription. Do not double doses. If you are taking tadalafil to treat PAH or BPH, follow your doctor’s directions and the guidelines in this paragraph. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco. Read and follow these instructions carefully. · For treatment of erectile dysfunction (as needed): Adults—10 milligrams (mg) as a single dose, no more than once a day, taken 30 minutes before you think sexual activity may occur. Your doctor may adjust your dose as needed. Children—Use is not recommended. For treatment of erectile dysfunction (daily use). What is Cialis? Cialis relaxes muscles of the blood vessels and increases blood flow to particular areas of the body. Cialis is used to treat erectile dysfunction (impotence) and symptoms of benign prostatic hypertrophy (enlarged prostate). Cialis is a PDE5 inhibitor medication approved for use for erectile dysfunction (ED) and benign prostatic hyperplasia. Don’t take Cialis with nitrate class medications. Doing so can cause a.