Red papular rash, mostly seen in eczema, psoriasis, lichen planus and other diseases, the clinical manifestations of different diseases vary. 1. Eczema: The occurrence of eczema is related to the joint action of many internal and external factors, which may lead to the appearance of red, itchy pimples, papules or dark red patches on the skin. 2. Psoriasis: The specific pathogenesis and etiology of psoriasis have not been fully elucidated, and it is considered to be related to the interaction of genetic background, environment and other factors. It leads to the appearance of red spots, papules and plaques with clear boundaries, covered with silvery-white scales and accompanied by itching. 3. Lichen planus: the pathogenesis of lichen planus is not clear, and it is considered to be related to oral medication, mental stress and other factors. It may lead to itchy, purplish-red flat papules in many parts of the patient’s body. The red papules appear on the skin, it is recommended to go to the dermatology department of the hospital, after a clear diagnosis, combined with the doctor’s advice to use medication, you can achieve the purpose of treating the disease.