The active lymph nodes in the parotid area suddenly become bigger may be due to lymphadenitis, lymph node tuberculosis, lymphatic tumor and other reasons. 1. Lymphadenitis: viruses or bacteria invade the skin and mucous membranes at the infectious lesions, resulting in inflammation of the lymph nodes, which causes painful enlargement of the lymph nodes and localized redness, and purulent secretions may appear when the parotid ducts are pressed. 2. Lymphatic tuberculosis: lesions caused by Mycobacterium tuberculosis invading the lymph nodes, which may be manifested as sudden swelling and pain in the lymph nodes of the parotid region, accompanied by night sweating (abnormal sweating after going to sleep, and sweating stops after waking up), low-grade fever, and malaise, and so on. 3. Lymphoma: cells in lymphatic tissues grow uncontrollably and randomly in the process of proliferation, forming different lumps, thus causing sudden enlargement of parotid lymph nodes, and the lymph nodes are hard and the surface is not smooth. Sudden enlargement of active lymph nodes in the parotid region is recommended to consult a doctor in time to clarify the cause of the disease for symptomatic treatment.