A lot of small particles on the forehead and chin may be caused by acne, contact dermatitis and folliculitis. 1. Acne: a lot of small particles on the forehead and chin may be acne vulgaris, which is related to heredity, androgen-induced sebum secretion, keratinization of the sebaceous gland ducts of the hair follicles, propagation of Propionibacterium acnes, and immune-inflammatory response. 2. Contact dermatitis: If the forehead and chin are exposed to allergens or irritants, it can lead to localized allergic or irritant reactions, and many small pimples can appear. 3. Folliculitis: If the skin follicles at the forehead and chin are infected by bacteria, it can cause inflammatory reaction of multiple hair follicles, and many small particles appear. It is recommended to go to the hospital in time for those who have a lot of small particles on the forehead and chin, to clarify the cause of the disease, and to carry out standardized treatment under the guidance of the doctor, so as to avoid delaying the condition.