A lot of red pimples on the chin may be caused by acne, eczema, folliculitis and other diseases. 1. Acne: Acne may be caused by androgen secretion, excessive sebum secretion, abnormal keratinization of cells around hair follicles, and Propionibacterium acnes infection, etc. It occurs on the chin, cheeks and other parts of the body, and may appear as red pimples, pustules and other symptoms. 2. Eczema: Eczema is related to heredity, hormone levels, metabolic abnormalities and other factors, and is most commonly found on the face and hands. When eczema grows on the chin, the patient will have red pimples, oozing, vesicles and other symptoms. 3. Folliculitis: Folliculitis may be caused by bacterial, fungal and other pathogen infections, triggers include trauma, shaving, etc. When there is folliculitis on the chin, red papules, white pustules and other symptoms may appear. There are more causes of many red pimples on the chin, and patients are advised to be admitted to the hospital for examination.