Thick lips may be caused by adenoid facies, or due to adenolipitis, congenital factors, etc. 1. Adenoid facies: It is mainly caused by adenoid hypertrophy and inflammation of adenoids. If the condition is more serious, it may obstruct the airway, resulting in the symptom of open-mouth breathing. Long-term open-mouth breathing, the airflow will impact the hard palate, making it deformed and high arch, thus appearing the phenomenon of thick lips. 2. Adenolabial inflammation: its etiology is still unclear, and may be related to periodontitis, smoking and other reasons. Due to the stimulation of inflammation, patients can appear lip mucous gland hyperplasia, lip swelling and thickening and other symptoms. 3. Congenital factors: If the patient’s parents have thick lips, due to genetic reasons, the probability of the child’s lips are thicker. Thick lips caused by heredity is a normal physiological phenomenon and does not need to be treated. If the lips are suddenly thickened or accompanied by other discomforts, it is recommended to go to the hospital in a timely manner to clarify the cause of the disease and follow the doctor’s instructions for treatment to avoid delaying the condition.