Hard bumps on the head are usually caused by folliculitis, lipoma and sebaceous cysts. 1. Folliculitis: it is mainly caused by sebaceous glands secreting too much, resulting in blockage of hair follicles and bacterial invasion, which is manifested by the appearance of one or more scattered red bumps on the scalp with yellowish-white pus tips, which may have different degrees of pain. 2. Lipoma: generally belongs to benign tumors, which may be caused by chronic inflammation, heredity, systemic metabolic abnormalities and other reasons, mainly manifested as painless, smooth and well-moved lumps under the epidermis of the skin. 3. Sebaceous cysts: sebaceous cysts are mainly caused by the obstruction of sebaceous glands of hair follicles and the gathering of the cortex into cysts, which can occur in the head, and are mainly manifested as a round, medium-hardness lumps. There may be other reasons for the hard bags on the head, and it is recommended that the patient go to the hospital in time to clarify the cause of the disease and follow the doctor’s instructions to standardize the treatment.