Swollen and painful gums are usually caused by apical periapical inflammation or periodontitis, both of which may lead to headaches, as follows. 1. Periapical periodontitis: the suppurative phase of acute periapical periodontitis, when the pus accumulates under the periosteum the pain is most severe. The gums are red and swollen with pressure pain. Touching the affected tooth can cause severe pain, and the pain can radiate to cause headache. 2. Periodontitis: Periodontitis can develop into advanced periodontal abscess, for multiple periodontal abscess, the gums are swollen and painful, usually accompanied by generalized discomfort, which may cause headaches. Swollen gums lead to headaches may have other reasons, it is recommended to go to the hospital in time, with the help of the doctor to clarify the cause of the targeted treatment.