Experiencing swollen lymph nodes is common during or after a viral infection, as seen with illnesses like COVID-19. These small, bean-shaped structures are part of the body’s immune system, acting as surveillance points against foreign invaders. When the body encounters a pathogen, these nodes enlarge as they fight off infection. This temporary swelling signals an active immune response.
Understanding Lymph Nodes
Lymph nodes are tiny, oval-shaped organs within the lymphatic system, which helps maintain fluid balance and defend the body against disease. They are located throughout the body, with clusters in the neck, armpits, and groin. These nodes filter lymphatic fluid, trapping harmful substances like bacteria, viruses, and abnormal cells.
Inside lymph nodes, specialized white blood cells called lymphocytes activate to combat infections. These immune cells multiply rapidly when they detect a threat. The increased number of these cells and the inflammatory response they trigger cause the lymph nodes to swell, often becoming tender or painful. Once the body has successfully neutralized the foreign invader, the lymph nodes return to their normal size.
COVID-19 and Swollen Lymph Nodes
Both COVID-19 infection and vaccination can cause swollen lymph nodes, reflecting the body’s immune response. When infected with the SARS-CoV-2 virus, lymph nodes, particularly in the neck, may swell as the immune system works to clear the infection. This swelling is often accompanied by other COVID-19 symptoms like cough, congestion, and sore throat. The enlargement appears within a few days of infection and can persist for several weeks.
Swollen lymph nodes are also a recognized side effect of COVID-19 vaccination. This immune response causes swelling in the armpit or neck on the same side as the injection site. The vaccine prompts immune cells to migrate to regional lymph nodes, stimulating an immune response.
Lymph node swelling from vaccination appears within one to two days after the shot and resolves within 10 days, though some cases have reported persistence for up to six months. While swelling from infection can affect nodes in various areas, vaccine-induced swelling is localized to the injection arm’s regional nodes. It is a temporary and expected sign that the vaccine is effectively building immunity.
When to Consult a Doctor
While swollen lymph nodes are a harmless sign of your body fighting off an infection, certain characteristics warrant medical evaluation. You should consult a healthcare professional if the swelling persists for more than two to four weeks in adults, or five days in children, or if the nodes continue to grow. Nodes that feel hard, are fixed in place, or do not move when pressed are also concerning signs.
Seek medical attention if the swollen nodes are accompanied by other symptoms such as unexplained weight loss, persistent fever, or night sweats. Difficulty swallowing or breathing, or if the skin over the node becomes red, warm, or shows signs of pus, also indicates a need for professional assessment. Swollen nodes in specific locations, like above the collarbone or near the elbow, may indicate more serious underlying conditions and should be checked by a doctor.