A bulging hard lump under the chin may be caused by boils, enlarged lymph nodes, epidermal cysts and other diseases, which can be treated by topical medications, oral medications and surgical treatments. 1. Boils: Inadequate facial cleansing can easily lead to infection of hair follicles and surrounding tissues and formation of boils, which appear as hard lumps on the chin. It can be treated with topical medications such as mupirocin ointment and fusidic acid ointment under doctor’s guidance. 2. Swollen lymph nodes: There is an abundance of lymph nodes under the chin, which may become enlarged in case of infection in the mouth or throat. It can be treated by symptomatic treatment of the infected foci under the guidance of a doctor. 3. Epidermoid cysts: Epidermoid cysts are cystic swellings containing keratin within the dermis. If the patient has no discomfort, no treatment can be taken, but if it affects the aesthetics or if the cyst grows too fast, it can be surgically removed. Patients who have bulging hard lumps under the chin should go to the hospital in time, after clarifying the cause of the disease under the guidance of the doctor for proper treatment.