Lymph nodes are small, bean-shaped structures within your immune system. They act as filters, trapping viruses, bacteria, and other harmful substances before they spread. They also house immune cells that fight infections. Understanding their normal size and when changes are a concern can help you monitor your health.
Understanding Normal Lymph Node Size
Healthy lymph nodes are typically small, often pea-sized or less than 1 centimeter in diameter. They are soft, movable under the skin, and not tender or painful. While many lymph nodes are not usually palpable, some in areas like the neck, armpits, and groin may be felt with gentle pressure.
The normal size of a lymph node can vary slightly depending on its location. For instance, lymph nodes in the groin area might naturally be a bit larger than those found in the neck. When medical professionals measure lymph nodes, especially in imaging, they often refer to the short axis diameter, which is generally considered the more accurate measurement.
Common Causes of Lymph Node Enlargement
Lymph nodes commonly enlarge when your body fights an infection or inflammation. This swelling occurs because immune cells within the nodes multiply rapidly to combat pathogens, leading to an accumulation of fluid and cells. Common examples include viral infections like the common cold, flu, or mononucleosis. Bacterial infections such as strep throat, ear infections, or skin infections can also cause nearby lymph nodes to swell.
The location of the swollen lymph node often provides a clue about the underlying cause; for example, a throat infection might cause swelling in the neck nodes. While infections are the most frequent reason for enlargement, less common causes include autoimmune diseases, where the immune system mistakenly attacks healthy tissues, or certain cancers like lymphoma or other cancers that spread to the lymph nodes. Vaccinations can also lead to temporary lymph node swelling.
When to Seek Medical Advice
While most enlarged lymph nodes resolve as the underlying infection clears, certain characteristics warrant medical attention. Consult a healthcare professional if a lymph node remains enlarged for more than a few weeks without an obvious cause. Nodes that are rapidly growing, feel hard or rubbery, or are fixed and do not move freely under the skin are also concerning.
Seek medical advice if swollen lymph nodes are accompanied by other symptoms such as unexplained weight loss, persistent fever, night sweats, or fatigue. Nodes that are very painful, red, inflamed, or draining pus should also be evaluated promptly. These signs may indicate a more serious underlying condition.