Red rashes around the mouth may be caused by diseases such as perioral dermatitis, herpes orofacialis, acne, or other diseases such as contact dermatitis. 1. Perioral dermatitis: the etiology of perioral dermatitis is not yet clear, and it is considered to be caused by a variety of factors such as long-term topical glucocorticoid and fluoride toothpaste. The main symptoms of patients are perioral papules, erythema, pustules, etc., and there will be mild scaling, itching, burning sensation and other symptoms. 2. Oral and lip herpes: oral and lip herpes is mainly caused by herpes simplex virus infection, patients will appear in the corners of the mouth, lip edge and other parts of the dense blisters, and the phenomenon of erosion. In addition, oral and lip herpes will also lead to pain, burning sensation, fatigue and other symptoms. 3. Acne: Acne is mainly related to androgen levels and increased sebum secretion, etc. The main symptoms of patients are pimples, papules, pustules, etc., which are commonly found on the cheeks, forehead and jaw. 4. Other: contact dermatitis, folliculitis and other diseases can also lead to the phenomenon of red rash around the mouth. Patients with symptoms of a red rash around the mouth should seek medical attention in a timely manner and follow the doctor’s instructions, do not self-medication.