Cialis is the trade name and generic name for tadalafil tablets, which are known to improve erectile dysfunction in men, with side effects including headaches and indigestion. Tadalafil is a type 5 phosphodiesterase inhibitor indicated for the treatment of erectile dysfunction in men over the age of 18, with side effects including flushing and indigestion. It is also important to note that tadalafil is contraindicated in people who are allergic to any of the components of the product, and is also prohibited in combination with drugs such as nitrates (e.g. nitroglycerin). Therefore, those who have the need to use this drug must be standardized under the guidance of a doctor, do not blindly take the drug or increase or decrease the dosage of the drug, so as not to cause adverse consequences.