What are lymph and lymph nodes?

Lymph is a clear or slightly yellowish watery fluid that:

  • removes bacteria and certain kinds of proteins from tissues;
  • transports fat from the small intestine, and;
  • supplies the bloodstream with the mature white blood cells (lymphocytes) that are made in bone marrow.

Lymph is circulated through the body by lymphatic vessels, which are similar to blood vessels. White blood cells and the lymphatic system are important parts of the immune system, helping the body rid itself of germs, cells, or foreign matter that could cause disease.

Lymph nodes are small, bean-shaped structures near the lymphatic vessels. There are about 600 lymph nodes throughout the body, some in deep tissues and others closer to the skin. Clusters of nodes are found in the neck, armpits, abdomen, and groin. (These nodes can be felt with the fingers.) Other nodes are found in the chest, arms, and legs.

Immune cells are stored inside nodes. Fluid from surrounding tissues enter lymph nodes via lymphatic vessels or the nodes’ own tiny blood vessels. The fluid is filtered by the nodes to remove infectious germs, cells, or foreign matter. Fresh lymphocytes are supplied and the fluid is sent back to the bloodstream to distribute lymphocytes throughout the body.

The terms lymph nodes and lymph glands are often mistakenly used to mean the same thing. Lymph nodes are not actually glands because they don’t make or secrete any substances; they only act as filters.

What causes swollen lymph nodes?

Swollen lymph nodes commonly occur when the number of white blood cells inside them has increased in response to an infection or other illness. The number of disease-fighting cells builds rapidly, causing pressure and swelling inside lymph nodes.

In many cases, the lymph nodes that swell will be close to the site of an infection. For example, a person with strep throat might develop swollen lymph nodes in the neck.

In other instances, swollen lymph nodes could indicate injury, lymphoma (cancer of the lymphatic system), AIDS (acquired immune deficiency syndrome), or a cancer that has spread to the lymph nodes from another part of the body.

What are the symptoms of swollen lymph nodes?

In general, lymph nodes larger than 1 centimeter (0.4 inches) in diameter are considered abnormal. Swollen lymph nodes not only become enlarged, sometimes visibly so, but may also be painful to the touch.

A doctor should be consulted when certain symptoms are present. These include:

  • Nodes that are swollen for more than two weeks
  • Weight loss
  • Night sweats
  • Long-lasting fever
  • Fatigue
  • Nodes that are hard, fixed to the skin, or growing rapidly
  • Swollen nodes close to the collarbone or lower part of the neck. Swollen nodes in this area often indicate a cancerous condition.
  • Red or inflamed skin over swollen nodes
  • Difficulty breathing

How are swollen lymph nodes diagnosed?

Swollen lymph nodes are not a disease—they are a symptom, usually of a controllable infection but sometimes of a more serious condition.

The term lymphadenopathy refers to lymph nodes that are abnormal in size, shape, or number. In “localized” lymphadenopathy, lymph nodes in only one area are affected. In “generalized” lymphadenopathy, enlarged lymph nodes are found in two or more separate areas of the body. This almost always points to the presence of a serious systemic (all over the body) disease.

Determining whether the condition is localized or generalized is a key part of trying to find out what is causing swollen lymph nodes. To make a diagnosis, the doctor will:

  • Examine the swollen nodes in terms of: size; pain or tenderness when touched; consistency (whether hard or rubbery); matting (whether nodes feel joined together or move as a unit); and location (specific diseases can be tied to where the affected nodes are located).
  • Perform a physical examination, note all symptoms, and review the patient’s medical history.
  • Review any medications being taken. Some drugs, such as the anti-seizure medicine phenytoin (Dilantin®), can produce swollen lymph nodes.
  • Consider possible risk factors, such as sexual practices, intravenous drug use, recent travel, and occupation.
  • Order blood tests, other laboratory tests, or scans to see if a suspected disease is present.
  • Take a biopsy (tissue sample) of the largest or most abnormal node if observation and other tests do not provide a diagnosis.
Examples of conditions related to localized lymphadenopathy:
  • Conjunctivitis (inflammation [swelling] of the membrane of the inner eyelid)
  • Upper respiratory infection (common cold, strep throat, etc.)
  • Tinea (skin infection)
  • Tonsillitis (inflammation of the tonsils)
  • Mononucleosis-like syndromes (viral infection causing fever, sore throat, and general fatigue)
  • Cat-scratch disease (infection from a cat bite or scratch)
  • Pharyngitis (inflammation of the pharynx, or upper part of the tube that leads to the stomach)
  • Lymphogranuloma venereum (a sexually transmitted disease caused by a type of Chlamydia bacterium)
  • Chancroid (infectious venereal ulcer)
  • Sarcoidosis (granular wounds appearing in the liver, lungs, skin, or lymph nodes)
  • Tularemia (infectious disease transmitted from rodents)
  • Plague (highly infectious, usually fatal, epidemic disease)
Examples of conditions related to generalized lymphadenopathy:
  • Epstein-Barr virus (herpes virus that causes infectious mononucleosis and is associated with certain types of cancers)
  • Toxoplasmosis (parasitic disease acquired from contact with cats or their feces or with raw or undercooked meat)
  • Cytomegalovirus (herpes virus infection, often in the salivary glands)
  • HIV (human immunodeficiency virus) or AIDS (acquired immune deficiency syndrome)
  • Tuberculosis lymphadenitis (bacterial infection attacking the lymph nodes)
  • Secondary syphilis (second stage of the sexually transmitted disease syphilis)
  • Hepatitis B (blood infection that causes damage to the liver)
  • Lupus erythematosus (red, scaly patches on the face and upper body; cause is unknown)
  • Rheumatoid arthritis (inflammation of the joints)
  • Lymphoma (solid tumors in the lymphatic system)
  • Leukemia (cancer of the bone marrow)
  • Serum sickness (immune system overreaction to injected proteins such as those found in cephalosporins, penicillins, or sulfonamides)
  • Kawasaki disease (childhood disease of enlarged lymph nodes in the neck, and bright red rashes on the tongue and hands)
  • Lyme disease (bacterial inflammatory disease transmitted by tick bites)
  • Measles (viral infection, especially in children, resulting in fever and skin eruptions)
  • Rubella (viral infection, also known as German measles)
  • Brucellosis (bacterial infection from diseased animals or tainted meat or milk products)
  • Typhoid fever (bacterial infection causing fever, depression, skin eruptions on the chest and abdomen, and diarrhea)
  • Still’s disease (juvenile arthritis)
  • Dermatomyositis (immune system disorder causing muscular weakness and skin rashes)
  • Amyloidosis (hard, waxy deposits in various organs and tissues)

How are swollen lymph nodes treated?

The treatment for swollen lymph nodes depends on the cause. Antibiotics or antivirals will usually clear up a simple infection in skin or tissue, and the nodes will gradually return to normal size. Following treatment, a three- to four-week period of observation is advisable to make sure there are no further problems.

For serious systemic infections, immune disorders, or cancer, more aggressive treatments over a longer period of time will be needed.

How can swollen lymph nodes be prevented?

Steps that may help prevent swollen lymph nodes include following good health habits and avoiding drugs, risky sexual behaviors, and obvious causes of bacterial infection. However, there is no way to guarantee that swollen lymph nodes will not occur at some time, since there are so many different causes.


© Copyright 1995-2017 The Cleveland Clinic Foundation. All rights reserved.

This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 1/10/2017…#15219