Buns on the forehead that hurt when touched may be caused by acne, boils, trauma and other diseases. 1. Acne: The cause is mainly related to hormone level changes, sebaceous gland keratinization abnormality, bacterial infection and other factors. Inflammatory papules, pustules, pimples and other symptoms may appear locally, and some patients may experience pain, mostly on the cheeks, forehead, jaw and other parts of the body. 2. Boils: the cause is mainly related to Staphylococcus aureus infection, and the environment, poor hygiene habits and other factors can also trigger the disease. It mainly manifests as one or more nodules with redness, swelling and pain, and is commonly found on the face and neck. 3. Trauma: It is mainly related to the impact and knocking of external objects. The patient will appear hemispherical bulge locally, accompanied by pain, if the forehead is traumatized, there may be a long bag touching the situation will be painful. There are many reasons for the growth of bags on the forehead, and it is recommended to go to a regular hospital for examination to clarify the cause of the disease.