Painful bumps under the skin of the chin may be caused by acne vulgaris, boils, epidermal cysts and other diseases. 1. Acne vulgaris: its cause is related to bacterial infection, excessive sebum secretion, inflammation and other factors. Patients may present with pimples, nodules, cysts, pustules and other symptoms, which may manifest as painful bumps under the skin of the chin. 2. Boils: mostly caused by Staphylococcus aureus infection as well as excessive sweating, poor hygiene habits and other factors. Patients may present with multiple or one hemispheric painful nodules, which may manifest as painful bumps under the chin skin. 3. Epidermoid cysts: may be caused by skin injury, embryonic ectopic and other factors. It may appear as a raised skin swelling under the chin, which may be painful and tender if secondary to infection. There are many reasons that lead to the appearance of patients with lumps of pain under the skin of the chin, and it is recommended that patients go to a regular medical consultation to clarify the cause of the disease and follow the doctor’s instructions for treatment.