Reactive hyperplasia of submandibular lymph nodes may be caused by oropharyngeal infections, which are commonly caused by upper respiratory tract infections, inflammation in the oral cavity, inflammation of the thyroid gland, or connective tissue disease and metastasis of malignant tumors. 1. Upper respiratory tract infection: such as rhinitis, acute tonsillitis, acute pharyngitis and other upper respiratory tract infections of the nasopharynx and throat will cause submandibular lymph node reactive hyperplasia. 2. Inflammatory diseases in the oral cavity: such as gingivitis, inflammation caused by pulpitis, etc., can also cause reactive hyperplasia of submandibular lymph nodes. 3. Inflammation of the thyroid gland: acute thyroiditis, subacute thyroiditis, Hashimoto’s disease and other inflammatory diseases of the thyroid gland can also lead to reactive hyperplasia of the submandibular lymph nodes. 4. Connective tissue diseases such as rheumatic fever can cause reactive hyperplasia and enlargement of lymph nodes. Lymph node enlargement caused by connective tissue diseases is often accompanied by prolonged low or high fever, muscle or joint pain, skin rash and anemia. 5. Lymphatic metastasis of malignant tumors: lymphatic metastasis of malignant tumors to submandibular lymph nodes, or lymphoma invading submandibular lymph nodes can also lead to reactive hyperplasia of the lymph nodes. Therefore, if you find reactive hyperplasia of submandibular lymph nodes, you should go to the hospital in time to find out the cause of the disease and then treat it.