Swollen lymph nodes often raise concerns, leading many to wonder about their causes, including allergies. These small, bean-shaped structures indicate the body is actively responding to something. Understanding why they swell, especially with allergies, helps interpret these changes.
What Lymph Nodes Do
Lymph nodes are small, bean-shaped glands within the immune system. They are strategically located throughout the body, including the neck, armpits, and groin, acting as filters for lymph fluid. This fluid circulates through lymphatic vessels, collecting waste products, damaged cells, and foreign substances from tissues.
Inside the lymph nodes, specialized immune cells, such as lymphocytes, work to identify and destroy these harmful invaders. When the body encounters an infection, these immune cells multiply rapidly within the nodes. This increased activity causes the nodes to enlarge and often become tender, indicating the immune system is actively fighting off threats.
Allergies and Lymph Node Swelling
Allergies are an immune response where the body reacts to harmless substances (allergens) as threats. This triggers histamine release, causing inflammation and common allergy symptoms like sneezing, itchy eyes, and nasal congestion. While allergies activate the immune system, they typically cause localized inflammation in areas like the nasal passages or skin.
Direct, significant lymph node swelling is not a common primary symptom of allergic reactions. However, in some instances, allergies can indirectly contribute to mild lymph node enlargement. This can occur when the sustained inflammation from an allergic response, particularly in areas like the sinuses or throat, leads to a secondary infection. For example, chronic nasal congestion from allergies can create an environment conducive to bacterial growth, resulting in a sinus infection that then causes nearby lymph nodes to swell.
Other Common Causes of Swollen Lymph Nodes
Swollen lymph nodes are most frequently a sign that the body is fighting off an infection. Viral infections (e.g., common cold, flu, mononucleosis) are common causes. Bacterial infections like strep throat, ear infections, or skin infections (e.g., cellulitis) also frequently cause lymph nodes to swell, often in the region closest to the infection site.
Beyond infections, inflammatory conditions can also lead to lymph node enlargement. Autoimmune diseases, where the immune system mistakenly attacks the body’s own tissues, such as lupus or rheumatoid arthritis, can result in widespread lymph node swelling. Less commonly, certain cancers (e.g., lymphoma or those that have spread) can enlarge lymph nodes, making them feel hard or rubbery. Vaccinations can also temporarily cause swelling in nearby lymph nodes as the immune system responds to the vaccine.
When to Seek Medical Attention for Swollen Lymph Nodes
While many instances of swollen lymph nodes resolve on their own, especially when tied to a common infection, certain signs warrant medical evaluation. Consult a healthcare professional if a swollen lymph node has no clear cause, continues to enlarge, or remains swollen for more than two to four weeks in adults. Nodes that feel hard, rubbery, or do not move when pressed should also be examined.
Seek medical attention if swollen lymph nodes are accompanied by unexplained fever, night sweats, or unintentional weight loss. Also seek advice if the skin over the swollen node becomes red, irritated, or warm, or if the node is very painful or rapidly growing. Self-diagnosis is not recommended; a healthcare provider can determine the cause and appropriate action.