Pirfenidone is a drug used for pulmonary fibrosis, mainly for mild to moderate idiopathic pulmonary fibrosis. Some side effects may occur during use. Patients may experience gastrointestinal reactions such as nausea, indigestion, vomiting, and anorexia. Patients may also experience photoallergic reactions and may develop a rash after use. Therefore, it is advisable for patients to use sunscreen and avoid exposure to ultraviolet light to prevent skin allergic reactions when using this drug. In addition, liver function damage may occur, and patients may experience elevated transaminases and jaundice, so patients are advised to monitor liver function regularly. There may also be side effects on the nervous system, such as drowsiness, dizziness, unsteadiness in walking, etc. Patients are advised not to engage in work requiring high concentration such as driving, working at heights, or operating machinery while taking the drug.