Swollen lymph nodes often prompt concern, particularly when new illnesses emerge. These small, bean-shaped structures are part of the immune system, located throughout the body, including the neck, armpits, and groin. Lymph nodes function as filters for lymph fluid, which circulates through the lymphatic system, collecting waste products, foreign particles, and abnormal cells from tissues. Within these nodes, immune cells, such as lymphocytes, identify and neutralize harmful substances like bacteria and viruses. When the body encounters an infection or illness, these immune cells multiply and activate, causing the lymph nodes to swell as part of a normal, protective response.
Swollen Lymph Nodes and COVID-19
Swollen lymph nodes, medically known as lymphadenopathy, can occur with COVID-19, though they are not considered a common symptom of the infection itself. When they do appear, it often signals an immune response to the SARS-CoV-2 virus. Swelling is observed in regions near the infection site, such as the neck, especially if symptoms like a sore throat or upper respiratory issues are present. This lymph node enlargement usually develops within a few days of infection and can persist for several weeks.
Differentiate lymph node swelling due to COVID-19 infection from swelling that can occur after COVID-19 vaccination. Swollen lymph nodes are a temporary side effect of COVID-19 mRNA vaccines. This indicates the immune system is building protection against the virus. The swelling is most frequently noted in the armpit on the vaccinated side, but it can also appear in the neck or above the collarbone. While generally temporary and resolving within a few weeks, this vaccine-induced swelling can sometimes be visible on imaging tests for a month or longer.
Other Reasons Lymph Nodes Swell
Beyond COVID-19, lymph nodes swell in response to common infections and inflammatory conditions. Bacterial or viral infections, such as the common cold, flu, strep throat, ear infections, or mononucleosis, are frequent causes. In these cases, the immune cells within the nodes proliferate to combat the pathogens, leading to the noticeable enlargement and tenderness. Skin infections or dental issues can also cause localized lymph node swelling in the adjacent areas.
Certain inflammatory conditions and autoimmune diseases can also cause generalized lymph node enlargement throughout the body. Conditions like lupus and rheumatoid arthritis involve the immune system mistakenly attacking healthy body tissues, and this systemic inflammation can manifest as swollen lymph nodes. While less common, persistent or unusual lymph node swelling can sometimes signal more serious underlying conditions. These include certain cancers, such as lymphoma or leukemia, or chronic infections like tuberculosis. Serious causes are far less frequent than benign infections.
When to Seek Medical Advice
While swollen lymph nodes are often normal signs of the body fighting off a minor infection, there are situations that warrant medical attention. If a swollen lymph node has no clear cause, such as a recent infection, or if it continues to enlarge or remains swollen for more than two to four weeks, consult a healthcare professional. Nodes that feel very hard, are fixed in place, or do not move when pressed also require evaluation.
Also seek medical advice if the swollen lymph nodes are accompanied by concerning symptoms. These include unexplained weight loss, night sweats, a persistent fever, or a cough that does not improve. Swelling in unusual locations, such as above the collarbone, or generalized swelling affecting multiple areas of the body, also warrants a medical visit. Additionally, any difficulty swallowing or breathing associated with swollen lymph nodes requires immediate medical care.