The forehead pimple is very big, hard and swollen may be cystic acne, sebaceous cysts, the patient should consult a doctor in time, clear the cause of the disease after treatment. 1. Cystic acne: Inflammatory dermatosis involving hair follicle infections, which occurs on the head, face, buttocks, and also on the forehead, cystic acne can be painful when pressed, and should be kept clean, and topical fusidic acid and mupirocin ointment should be used. 2. Sebaceous cysts: a very large, hard and swollen “pimple” on the forehead may be sebaceous cysts, sebaceous cysts are benign lesions formed by the gradual accumulation of sebum, when accompanied by infection there will be localized redness and swelling as well as pain, and can be waited until the infection subsides to perform surgical excision. It is recommended that the patient go to the dermatology department of the hospital as soon as possible to get a clear diagnosis, and choose the appropriate treatment plan under the advice of the doctor, and all the above medicines should be used under the guidance of the doctor.