Lymph nodes are tiny, bean shaped organs that filter lymph fluid. They are located throughout the body, but particular collections are found just under the skin in the neck, under the arms, and in the groin area. Lymph nodes are part of the lymphatic system (see Biology of the Immune System: Lymphatic System: Helping Defend Against Infection), which is one of the body's defense mechanisms against the spread of infection and cancer.

Lymph is clear fluid that is made up of water, white blood cells, proteins, and fats that have filtered out of blood vessels into the spaces between cells. Some of the fluid is reabsorbed by the blood vessels but the rest enters the lymphatic vessels. Lymph then passes through the lymph nodes, which are specific collection points where damaged cells, infectious organisms, and cancer cells are filtered from the fluid and destroyed. If many infectious organisms or cancer cells are present, the lymph nodes swell. Sometimes, organisms cause infection within a lymph node.

A few small nodes often can be felt in healthy people. Lymph nodes that are larger and easily felt may be a sign of a disorder. Some people use the term "swollen glands" to refer to swollen lymph nodes, especially when the nodes in the neck are swollen. However, lymph nodes are not glands. Doctors use the term lymphadenopathy to refer to swollen lymph nodes.

Lymph nodes in only one body area may be swollen, or nodes in two or more body areas can be swollen. When swollen lymph nodes are painful or have signs of inflammation (for example, redness or tenderness), the condition is termed lymphadenitis. Other symptoms, such as sore throat, runny nose, or fever, may be present, depending on the cause. Sometimes swollen lymph nodes are discovered when the person is being examined because of another symptom.

Causes

Because lymph nodes participate in the body's immune response, a large number of infections, inflammatory disorders, and cancers are potential causes. Only the more common causes are discussed here.

The most common causes are

• Upper respiratory infections (URI)
• Infections in tissues near the swollen lymph node

Sometimes doctors cannot determine the cause of the swelling, but swelling goes away on its own without causing the person any harm.

The most dangerous causes are cancer, human immunodeficiency virus (HIV) infection, and tuberculosis. However, probably less than 1% of people with swollen lymph nodes have cancer.

Evaluation

Not every person with swollen lymph nodes requires immediate evaluation by a doctor. The following information can help people decide when a doctor's evaluation is needed and help them know what to expect during the evaluation.

Warning signs: In people with swollen lymph nodes, certain symptoms and characteristics are cause for concern. They include

• A node that is an inch or more in diameter
• A node that is draining pus
• A node that feels hard
• Risk factors for HIV infection (such as occupational exposure, high-risk sexual activities, injecting street drugs) or tuberculosis (such as living or working with a person who has tuberculosis or having recently moved from an area where tuberculosis is prevalent)
• Fever or unexplained weight loss

When to see a doctor: If a lymph node is very painful or draining pus or other material, people should see a doctor right away. Other people should call their doctor. The doctor will decide how quickly they need to be seen based on the presence of warning signs and other symptoms. For people who have no warning signs and otherwise feel well, a delay of a week or so is not harmful.

What the doctor does: The doctor first asks questions about the person's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause of the swollen lymph nodes and the tests that may need to be done (see Lymphatic Disorders: Some Causes and Features of Swollen Lymph Nodes).

Doctors ask

• Where the swollen nodes are located
• How long nodes have been swollen
• Whether the person has pain
• Whether the person has recently had an injury (particularly cat scratches and rat bites)
• Whether the person has an infection or symptoms of an infection (for example, a runny nose, cough, fever, sore throat, unexplained weight loss, or tooth or gum pain)

Doctors then do a physical examination. Doctors check for fever and examine areas where lymph nodes are found. Doctors check the person for any signs of infection or lumps elsewhere in the body. People who have swollen lymph nodes throughout the body usually have a disorder that affects the entire body. However, people who have swollen lymph nodes in only one area may have a disorder that affects only that area (for example, an infection) or more widespread disease.

Sometimes the history and physical examination suggest the cause, as for example when the person has an upper respiratory infection or a dental infection (see Lymphatic Disorders: Some Causes and Features of Swollen Lymph Nodes). In other cases, findings do not point to a single cause. People with warning signs are more likely to have a serious disorder, but people with lymph node swelling and no other symptoms may also have a serious disorder.

Nodes that are hard, very enlarged, and do not move when pushed may indicate cancer. Tenderness, redness, and warmth in a single enlarged lymph node may indicate an infection of the node.

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Some Causes and Features of Swollen Lymph Nodes Cause Common Features* Tests Infections Upper respiratory infection (including sore throat) Neck nodes are affected with only little or no tenderness Sore throat, runny nose, or cough Only a doctor's examination Dental infection Neck nodes on one side are affected (often tender) Painful tooth Only a doctor's examination Mononucleosis Swelling on both sides, typically in the neck but sometimes under the arms or in the groin Fever, sore throat, and severe fatigue Typically in an adolescent or a young adult Blood test for mononucleosis Tuberculosis affecting the lymph nodes Usually swelling of nodes in the neck or above the collarbone Sometimes lymph nodes inflamed or draining Often in a person who has HIV infection Tuberculin skin testing Usually lymph node aspiration or biopsy HIV (immediately after the person became infected—the primary infection) Generalized lymph node swelling Usually fever, malaise, rash, and joint pain Often in a person known to have been exposed to HIV or to having exposure to a high-risk activity (such as occupational exposure, high-risk sexual activities, injecting street drugs) HIV blood testing STDs (particularly herpes simplex, chlamydia, and syphilis) Except for secondary syphilis, only swollen nodes in the groin Often urinary symptoms (such as, pain during urination) and urethral or vaginal discharge Sometimes sores on the genitals For secondary syphilis, often widespread sores on the mucous membranes and widespread lymph node swelling STD testing Skin and soft tissue infections (for example, cellulitis, abscess, cat scratch disease), including direct lymph node infection Usually a visible cut or infection of the skin near the swollen node Usually only a doctor's examination Sometimes, blood tests to identify antibodies to the infecting organism Toxoplasmosis Swollen nodes on both sides of the neck and under both arms Sometimes flu-like symptoms and an enlarged liver and spleen Often history of exposure to cat feces Blood tests Cancers Leukemias (typically chronic and sometimes acute lymphocytic leukemia) Fatigue, fever, and weight loss With acute leukemia, often easy bruising and/or bleeding Complete blood count and peripheral smear (examination of a blood sample with a microscope to determine characteristics of the cells) Bone marrow examination Lymphomas Painless lymph node swelling (local or widespread) Nodes often rubbery and sometimes clumped together Often fever, night sweats, and weight loss Lymph node biopsy Metastatic cancers (often of the head and neck, thyroid, breast, or lung) One or several painless nodes in the neck Nodes often hard, sometimes unable to be moved when pushed Tests to identify the primary tumor, often including looking in the throat, esophagus, and trachea with a flexible tube Connective tissue disorders Systemic lupus erythematosus (SLE) Widespread node swelling Typically painful and sometimes swollen joints Sometimes red rash affecting the nose and the cheeks and other skin sores A doctor's examination plus blood tests Sarcoidosis Painless lymph node swelling that may be widespread Often cough and/or shortness of breath, fever, malaise, muscle weakness, weight loss, and joint pains Chest imaging (plain x-ray or CT) Sometimes lymph node biopsy Kawasaki disease Tender swollen nodes in the neck in a child Fever, usually higher than 102° F (39° C), rash on the trunk, prominent red bumps on the tongue, peeling skin on the palms, soles and around the nails Only a doctor's examination Other Drugs: Common drugs include allopurinol, antibiotics (for example, cephalosporins, penicillin, and sulfonamides), atenolol, captopril, carbamazepine, phenytoin, pyrimethamine, and quinidine History of using a causative drug Except for phenytoin, rash, joint and muscle pain, and fever Only a doctor's examination Silicone breast implants Node swelling under the arms in a woman with breast implants A doctor's examination and often tests for other causes of node swelling *Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present. CT = computed tomography; HIV = human immunodeficiency virus; STD = sexually transmitted disease. Some Causes and Features of Swollen Lymph Nodes Cause Common Features* Tests Infections Upper respiratory infection (including sore throat) Neck nodes are affected with only little or no tenderness Sore throat, runny nose, or cough Only a doctor's examination Dental infection Neck nodes on one side are affected (often tender) Painful tooth Only a doctor's examination Mononucleosis Swelling on both sides, typically in the neck but sometimes under the arms or in the groin Fever, sore throat, and severe fatigue Typically in an adolescent or a young adult Blood test for mononucleosis Tuberculosis affecting the lymph nodes Usually swelling of nodes in the neck or above the collarbone Sometimes lymph nodes inflamed or draining Often in a person who has HIV infection Tuberculin skin testing Usually lymph node aspiration or biopsy HIV (immediately after the person became infected—the primary infection) Generalized lymph node swelling Usually fever, malaise, rash, and joint pain Often in a person known to have been exposed to HIV or to having exposure to a high-risk activity (such as occupational exposure, high-risk sexual activities, injecting street drugs) HIV blood testing STDs (particularly herpes simplex, chlamydia, and syphilis) Except for secondary syphilis, only swollen nodes in the groin Often urinary symptoms (such as, pain during urination) and urethral or vaginal discharge Sometimes sores on the genitals For secondary syphilis, often widespread sores on the mucous membranes and widespread lymph node swelling STD testing Skin and soft tissue infections (for example, cellulitis, abscess, cat scratch disease), including direct lymph node infection Usually a visible cut or infection of the skin near the swollen node Usually only a doctor's examination Sometimes, blood tests to identify antibodies to the infecting organism Toxoplasmosis Swollen nodes on both sides of the neck and under both arms Sometimes flu-like symptoms and an enlarged liver and spleen Often history of exposure to cat feces Blood tests Cancers Leukemias (typically chronic and sometimes acute lymphocytic leukemia) Fatigue, fever, and weight loss With acute leukemia, often easy bruising and/or bleeding Complete blood count and peripheral smear (examination of a blood sample with a microscope to determine characteristics of the cells) Bone marrow examination Lymphomas Painless lymph node swelling (local or widespread) Nodes often rubbery and sometimes clumped together Often fever, night sweats, and weight loss Lymph node biopsy Metastatic cancers (often of the head and neck, thyroid, breast, or lung) One or several painless nodes in the neck Nodes often hard, sometimes unable to be moved when pushed Tests to identify the primary tumor, often including looking in the throat, esophagus, and trachea with a flexible tube Connective tissue disorders Systemic lupus erythematosus (SLE) Widespread node swelling Typically painful and sometimes swollen joints Sometimes red rash affecting the nose and the cheeks and other skin sores A doctor's examination plus blood tests Sarcoidosis Painless lymph node swelling that may be widespread Often cough and/or shortness of breath, fever, malaise, muscle weakness, weight loss, and joint pains Chest imaging (plain x-ray or CT) Sometimes lymph node biopsy Kawasaki disease Tender swollen nodes in the neck in a child Fever, usually higher than 102° F (39° C), rash on the trunk, prominent red bumps on the tongue, peeling skin on the palms, soles and around the nails Only a doctor's examination Other Drugs: Common drugs include allopurinol, antibiotics (for example, cephalosporins, penicillin, and sulfonamides), atenolol, captopril, carbamazepine, phenytoin, pyrimethamine, and quinidine History of using a causative drug Except for phenytoin, rash, joint and muscle pain, and fever Only a doctor's examination Silicone breast implants Node swelling under the arms in a woman with breast implants A doctor's examination and often tests for other causes of node swelling *Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present. CT = computed tomography; HIV = human immunodeficiency virus; STD = sexually transmitted disease.

Testing: If doctors suspect a specific disorder (for example, mononucleosis in a young person with fever, sore throat and an enlarged spleen), initial testing is directed at that condition (see Lymphatic Disorders: Some Causes and Features of Swollen Lymph Nodes).

If history and physical examination do not show a likely cause, further testing depends on the nodes involved and the other findings present.

People with warning signs and those with widespread lymph node swelling should have a complete blood count and chest x-ray. Doctors may also test for tuberculosis, HIV infection, and mononucleosis. Sometimes blood tests are needed to detect toxoplasmosis and syphilis. In people with joint pain or stiffness or a rash, blood tests are done for systemic lupus erythematosus (lupus).

If doctors suspect cancer or lymphoma, the person has a lymph node biopsy. Biopsy may also be needed when widespread lymph node swelling does not resolve within three to four weeks.

Treatment

Primary treatment is directed at the cause. Swollen lymph nodes are not treated.

Key Points

• In most cases the cause is an obvious nearby skin or tissue infection or a harmless viral infection that goes away on its own.
• Testing is usually needed when there are warning signs, when other symptoms or risk factors suggest a specific disorder, or when widespread lymph node swelling has no apparent cause.
• When lymph node swelling does not resolve within 3 or 4 weeks, a biopsy may be needed.

Last full review/revision August 2012 by James D. Douketis, MD