The common causes of erythema on chest include solar dermatitis, eczema, pityriasis rosea, lupus erythematosus and so on. 1. Solar dermatitis: usually caused by prolonged exposure to strong sunlight, it can be manifested as erythema multiforme on the face and neck, chest and other areas directly exposed to ultraviolet rays, with a burning sensation, itching and pain. It is recommended to avoid prolonged direct exposure to the sun, and apply sunscreen and use umbrellas when going out. 2. Eczema: It is an inflammatory reaction of the skin caused by many factors, and can appear on the forearms, calves, face, chest and other parts of the body. It is usually characterized by erythema and papules, mostly symmetrically distributed, and accompanied by erosion and itching. Patients are advised to eat less stimulating food and allergy-prone food. 3. pityriasis rosea: it is an inflammatory skin disease mainly manifested by furfuraceous scaly spots, usually round or oval erythematous or yellow-brown spots, mostly occurring in the proximal limbs and trunk, so it can also lead to the manifestation of erythema on the forehead. This disease is self-limiting. 4. Lupus erythematosus: it is a kind of autoimmune disease that can involve multiple systems, which can be manifested as bilateral symmetrical erythema pteronyssinus, and the erythema pteronyssinus can occur in any part of the body, and erythema pteronyssinus of the face has specificity. The erythema can occur in any part of the body, and the erythema pteronyssinus of the face is specific. In conclusion, erythema on chest can be caused by different reasons, it is recommended to go to regular hospitals in time to get a clear diagnosis and follow the doctor’s instructions for treatment.