Cialis is the trade name, generic name is tadalafil, 5mg is taken in small doses, prolonged small doses of tadalafil can improve erectile dysfunction in men. Tadalafil is a PDE-5 inhibitor used for the treatment of erectile dysfunction in men, and 5mg is taken as a small dose application to slow down blood circulation disorders in the penis, thus improving erectile dysfunction. In addition, the incidence of side effects is correlated with the concentration of the drug in the blood, so the 5mg dosage results in fewer side effects. However, it should be noted that the use of tadalafil may cause adverse reactions such as headache, back pain, and indigestion. Tadalafil is contraindicated in people who are allergic to any of the ingredients in the product, patients who are taking any form of nitrates, guanylate cyclase stimulators, women, children and other people. The drug is a prescription drug and should be applied in strict compliance with the doctor’s instructions.