What Causes Swollen Lymph Nodes? (2024)

Swollen lymph nodes in your neck, armpit, head, and other parts of the body often occur when your body is fighting an infection or disease. Also known as lymphadenopathy, it can also sometimes be due to a drug side effect, autoimmune disease, or, in rare cases, cancer.

Lymph nodes are tiny organs that filter fluids from the lymphatic system. If the immune system recognizes something harmful in the lymph node, it will trigger an immune response in the form of lymphocytes. These white blood cells help fight infection and disease. The inflammation associated with the immune assault will cause the lymph nodes to swell.

Swollen lymph nodes often return to their normal size after your body fights off an infection. They usually aren't a cause for worry unless they stay large over several weeks or if they feel hard or irregular. You should also see a healthcare provider if you have accompanying symptoms like fever, night sweats, or weight loss.

Symptoms

Swollen lymph nodes may be localized to one part of the body (such as due to a local infection or early-stage cancer) or affect multiple parts of the body (such as with a systemic disease or advanced metastatic cancer).

They may be palpable (meaning that you can feel them), while others are non-palpable (meaning you cannot). The swelling may be acute (meaning sudden and severe) or chronic (meaning persistent). These features can help your healthcare provider narrow the possible causes.

Palpable swollen lymph nodes can be recognized by symptoms like:

• Hardened bumps beneath the skin that you can feel beneath the skin, such as in the neck or groin
• Hardened bumps that are visibly seen, such as in the armpit, neck, groin, or behind the ear
• Warmth, redness, tenderness, or pain
• Fever
• Body aches
• Fatigue

In the absence of palpable bumps, a person may only experience fever, body aches, fatigue, or no symptoms at all.

Infectious Causes of Swollen Lymph Nodes

The swelling of lymph nodes is most commonly caused by inflammation, referred to as lymphadenitis. This is usually due to an infection somewhere in the body.

Bacterial, viral, parasitic, and fungal infections are common causes of swollen lymph nodes. Some infections, like an upper respiratory infection, may cause localized swelling, while systemic (whole-body) infections can cause generalized swelling.

Some of the more common infectious causes of lymphadenopathy include:

• Colds and flu
• Dental infections
  
• Ear infections
• Hepatitis
  
• HIV
• Infectious mononucleosis
• Lyme disease
• Mumps
• Parasitic worms (helminths)
  
• Sexually transmitted infections (STIs)
• Shingles
• Staph infection
• Strep throat
• Tonsillitis
• Tuberculosis

Certain infections can lead to the formation of a lymph node abscess, particularly those that are severe or prolonged. Abscesses are inflamed and often painful pockets of pus that may require drainage and antibiotic drugs to clear them.

Autoimmune Causes

Swollen lymph nodes are common with certain autoimmune disorders. These are diseases in which the immune system mistakenly attacks normal tissues with inflammation.

Autoimmune causes of lymphadenopathy include:

• Dermatomyositis
  
• Kawasaki disease
• Lupus
• Rheumatoid arthritis (RA)
• Sarcoidosis
• Sjögren's disease
• Still disease (juvenile rheumatoid arthritis)

Autoimmune lymphadenopathy can be difficult to distinguish from infectious lymphadenopathy and may only be identified after early testing fails to uncover an infectious cause.

Medication Causes

Certain medications can also cause swollen lymph nodes. In such cases, lymphadenopathy can be reversed if the drug can be stopped or substituted.

Among the drugs that can cause swollen lymph nodes are:

• Apresoline (hydralazine)
• Cephalosporin antibiotics
• Capoten (captopril)
• Dilantin (phenytoin)
  
• Mysoline (primidone)
• Penicillins
  
• Quinidex (quinidine)
• Rituxin (rituximab)
• Sulfa drugs
• Tegretol (carbamazepine)
• Tenormin (atenolol)
• Zyloprim (allopurinol)
  

When Are Swollen Lymph Nodes a Sign of Cancer?

Swollen lymph nodes are rarely a sign of cancer. However, painless swelling of one or more lymph nodes is a sign that your condition is not infectious and warrants immediate investigation.

This is especially true if lymphadenopathy is getting worse, spreading to other parts of the body, or is accompanied by symptoms such as loss of appetite, unintentional weight loss, easy bruising, or night sweats.

Among the cancers for which lymphadenopathy is common, include:

• Breast cancer
• Genital cancers (such as penile cancer or vulvar cancer)
• Head and neck cancers
• Hodgkin lymphoma
• Leukemia
• Non-Hodgkin lymphoma
• Melanoma and other skin cancers
• Metastatic cancer (cancer that has spread from other parts of the body)

When to See a Healthcare Provider

Swollen lymph nodes are usually a sign that your body is fighting an infection. If symptoms are mild, they may resolve on their own once the infection is cleared, such as with the flu.

However, swollen lymph nodes should be seen by a healthcare provider if they are:

• Very large and growing
• Painless
• Feel hard, are irregularly shaped, or are fixed in place
• Accompanied by fever, night sweats, or unexplained weight loss

In children, any lymph node larger than about 1/2 inch should be seen by a healthcare provider.

Lymph nodes should return to normal within two to three weeks following an infection. If the swelling doesn’t go down or the lymph nodes still feel tender, see your healthcare provider.

Diagnosis and Treatment

To diagnose swollen lymph nodes, your healthcare provider will review your medical history and perform a physical exam. You'll be asked when your symptoms started and if the swelling was sudden or if it is persistent. The location and accompanying symptoms can often provide clues as to the underlying cause.

Additional tests may be ordered to help narrow the causes, such as:

• Blood tests, like a complete blood count (CBC) to check for signs of infection, an antinuclear antibody (ANA) test to check for signs of autoimmunity, and an STI panel to check for signs of sexually transmitted infections
  
• Imaging studies, such as ultrasound, X-ray, computed tomography (CT), or magnetic resonance imaging (MRI)
• Lymph nodebiopsy, in which a sample of a lymph node or the entire lymph node is removed for evaluation in the lab

Treatment for swollen lymph nodes can vary by the underlying cause. While you receive medical treatment, you can also try at-home remedies for symptoms. Pain and swelling in the lymph nodes can be eased with a cold compress or over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) like Advil (ibuprofen) or Aleve (naproxen).

Summary

Swollen lymph nodes in the neck, groin, armpit, or other parts of the body can be caused by an infection, autoimmune disease, medications, and certain cancers. The condition may be mild or severe, localized or generalized, acute or chronic. These factors can help the healthcare provider narrow the possible causes.

The diagnosis of lymphadenopathy may involve a physical exam, imaging studies, lab tests, and a lymph node biopsy. The treatment varies by the cause, but the pain and swelling can usually be relieved with a cold compress or an over-the-counter painkiller like Advil.

By Indranil Mallick, MD
Indranil Mallick, MD, DNB, is a radiation oncologist with a special interest in lymphoma.