Swelling of lymph nodes in the neck may be caused by microbial infections or tumors, if the swelling of lymph nodes in the neck subsides and then returns to the other side. 1. Microbial infection: if the lymph nodes are enlarged due to microbial infection, such as virus, bacteria, etc., the enlarged lymph nodes will subside after treatment, but when it is not completely cured, the enlarged lymph nodes will appear elsewhere. At this time, we should improve the examination, clarify the cause of the disease and give appropriate anti-infection treatment, and at the same time, we need to pay attention to the treatment of the primary infected foci. 2. Tumor diseases: when nasopharyngeal carcinoma, laryngeal carcinoma, thyroid carcinoma and other tumors metastasize, they will infiltrate lymphocytes and proliferate and differentiate in them, and the treatment can reduce the cancer cells, but it cannot kill the cancer cells completely, and the cancer cells will metastasize to other places, which will cause enlargement of other lymph nodes again. It should be noted that when the above situation occurs, one should go to the hospital in time for examination and treatment under the guidance of doctors.