Lymph nodes are tiny capsules, about the size of a pea or small bean that are filled with the cells that help protect the body from illness, which are types of white blood cells called macrophages and lymphocytes. When you get ill, these cells go into action to fight disease, and the lymph nodes may swell due to presence of disease or abnormal tissue in the lymph nodes. There are actually several reasons why lymph nodes become swollen, and many conditions that can cause painful swollen nodes. Which lymph nodes become swollen can sometimes help track which diseases are creating the problem.

Lymph nodes become swollen usually from bacterial or viral infections. As bacteria or viruses invade the nodes, they harden and inflame, and they can really begin to hurt. With colds and flus, you may note painfully swollen nodes around the throat, under the arms and at the groin. When lymph nodes reach very large sizes, especially those around the throat and under the jaw, you may have mumps. Other conditions may sometimes cause large lymph nodes around this area, like strep throat, measles, ear infections, cat scratch fever, gonorrhea, syphilis, toxoplasmosis, or mononucleosis.

Sometimes lymph nodes become swollen and indicate an infection present elsewhere in the body. For instance, if you have an infected cut or wound, or you have a blood infection, you may note lymph nodes become swollen throughout the body. Usually they are most swollen closest to the infection, if it’s on the skin.

In some cases, autoimmune disorders mean lymph nodes become swollen more or less chronically. This is because the body turns on itself, and produces extra white blood cells to attack regular aspects of the body it views as foreign tissue. Typical autoimmune disorders like lupus, rheumatoid arthritis, Hashimoto’s thyroiditis, or HIV may mean lymph nodes become swollen or remain swollen for long periods of time.

Swollen lymph nodes can also indicate the presence of foreign abnormal tissue in the nodes, in other words forms of cancer. Lymphoma for instance, specifically attacks the lymph system, and may result in one or more lymph nodes swelling. In other cases, blood cancers like leukemia, mean lymph nodes become swollen.

A swollen lymph node is usually considered to be .39 inches (about a centimeter) in diameter. You’ll definitely be able to feel swelling in most cases, and it can be painful. When you’ve had a doctor identify the cause, treatment of the causal factor can help gradually bring down lymph node swelling. In the interim, while treatment has not yet worked, you can address the discomfort by taking anti-inflammatory medications like ibuprofen. You can also use warm compresses on the swollen nodes to help bring some relief for the condition. Given the potentially serious causes of swollen lymph nodes, do check with a doctor if lymph node swelling doesn’t reduce in a few days.