Lymph nodes are normal organs of the body and are present in both adults and children. The main function of lymph nodes is to defend the body against various invasions encountered by the body. Lymph nodes are widely distributed in all parts of the body, and common areas where they gather include the back of the occipital area, the jaw, behind the ears, both sides of the neck, the armpits, the groin, and even next to the internal organs. Normal lymph nodes are characterized by a size of a soybean, a tough and soft texture, painlessness, no adhesion to surrounding tissues, and good mobility, and individual lymph nodes are large, up to 1~37.5px, and therefore easily palpable from under the skin. Lymph nodes are present in groups, each group of lymph nodes is about 1-3 or more, and the size is not uniform. Body surface lymph nodes are generally symmetrically distributed, symmetrical from side to side, but not necessarily increasing in size at the same time. Compared with other parts of the body, lymph nodes in the neck can be a large team, with as many as 70 lymph nodes, and those that can be palpated can reach more than 20. Some parents say that their children did not have lymph nodes before, but why are they so obvious now? That is because the size of lymph nodes varies among children of different ages. The lymph nodes of newborns (0-28 days after birth) and small infants (within 1 year) are the size of a grain of rice or a green bean, and because they have more fat, they are not easily palpable; after the age of 1, most of the lymph nodes of children can be palpable; after the age of 3, the subcutaneous fat decreases, and children can see the superficial lymph nodes in the neck when they tilt their heads; at the age of 7-8, the lymph nodes can be divided into lobules, and their ability to respond to infection can be controlled to a level similar to that of adults. After puberty, the size of lymph nodes in the neck often exceeds 25px; after sexual maturity, the lymph nodes basically stop growing, and some of them even have degeneration and cannot be touched. So, what exactly causes lymph node enlargement? Usually, any factor that causes changes in the immune function of the body may cause lymph node enlargement. Common primary causes of enlarged lymph nodes in the head and face include: cold (upper respiratory tract infection), cough, asthma, allergies, head and face rash, otitis media, mouth ulcers, tonsillitis, tooth replacement, dental caries, and even fatigue. Most lymph node hyperplasia does not require medication or even intravenous infusions. After the primary cause is removed, it is expected to return to normal after rest and conditioning. If you find that your child’s lymph nodes have not recovered but have become significantly larger, even with redness, swelling, tenderness, poor mobility or even multiple fusion, please go to the hospital promptly.