Lymph nodes are found throughout your body. They are an important part of your immune system. Lymph nodes help your body recognize and fight germs, infections, and other foreign substances.

The term "swollen glands" refers to enlargement of one or more lymph nodes.

In a child, a node is considered enlarged if it is more than 1 centimeter (0.4 inch) in diameter.

See also: Lymphadenitis and lymphangitis

Common areas where the lymph nodes can be felt (with the fingers) include:

• Groin
• Armpit
• Neck (there is a chain of lymph nodes on either side of the front of the neck, both sides of the neck, and down each side of the back of the neck)
• Under the jaw and chin
• Behind the ears
• On the back of the head

Lymph nodes can become swollen from infection, inflammatory conditions, an abscess, or cancer. Other causes of enlarged lymph nodes are rare. By far, the most common cause of swollen lymph nodes is infection.

When swelling appears suddenly and is painful, it is usually caused by injury or an infection. Enlargement that comes on gradually and painlessly may, in some cases, result from cancer or a tumor.

Infections that commonly cause swollen lymph nodes include:

• Abscessed or impacted tooth
• Ear infection
• Colds, flu, and other infections
• Gingivitis
• Mononucleosis
• Mouth sores
• Sexually transmitted diseases
• Tonsillitis
• Tuberculosis
• Skin infections

Immune or autoimmune disorders that can cause swollen lymph nodes include rheumatoid arthritis and HIV.

Cancers that can often cause swollen lymph nodes include leukemia, Hodgkin's disease, or non-Hodgkin's lymphoma. However, many other cancers may also cause this problem.

Which lymph nodes are swollen depends on the type of problem and the body parts involved. Identifying the location can help determine the possible cause.

Swollen lymph nodes may also be caused by some medications (such phenytoin for seizures) or certain vaccinations (such as typhoid immunization).

Soreness in lymph nodes usually disappears in a couple of days without treatment, but the nodes may not return to normal size for several weeks after the infection has cleared. Generally, if they are painful, it is because they swell rapidly in the early stages of fighting an infection.

Call your doctor if:

• Your lymph nodes do not get smaller after several weeks or continue to get larger.
• They are red and tender.
• They feel hard, irregular, or fixed in place.
• You have a fever, night sweats, or unexplained weight loss.
• Any node in a child is larger than 1 centimeter (a little less than 1/2 inch) in diameter.

Your doctor will perform a physical examination, checking all of your palpable lymph nodes for size, texture, warmth, tenderness, and other features.

Your doctor may ask the following medical history questions:

• Which nodes are affected?
• Is the swelling the same on both sides?
• When did the swelling begin?
• How long has it lasted (how many months or weeks)?
• Did it begin suddenly or did it develop gradually?
• Is the swelling increasing in size?
• Are the number of nodes that are swollen increasing?
• Are any of the swollen nodes painful or tender when you gently press on them?
• Is the skin over or around the nodes red?
• Have you had any other symptoms?

The following diagnostic tests may be performed:

• Physical exam
• Blood tests, including liver function tests, kidney function tests, and CBC with differential
• Lymph node biopsy
• Chest x-ray
• Liver-spleen scan

Armitage JO. Approach to the patient with lympadenopathy and splenomegaly. In: Goldman L. Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 174.

Camitta BM. Lymphadenopathy. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Kliegman: Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 490.