Your lymphatic system comprises a network of organs, vessels and numerous lymph nodes situated throughout your body. Most of your lymph nodes are located in your head and neck region. Lymph nodes that frequently swell are in this area, as well as in your armpits and groin area.
Swollen lymph nodes are a sign that something is wrong somewhere in your body. When your lymph nodes first swell, you might notice:
- Tender and painful lymph nodes
- Swollen lymph nodes that may be the size of a pea or kidney bean, or even larger
Depending on the cause of your swollen lymph nodes, other signs and symptoms you might have include:
- Runny nose, sore throat, fever and other indications of an upper respiratory infection
- General swelling of lymph nodes throughout your body — which may indicate an infection, such as HIV or mononucleosis, or an immune disorder, such as lupus or rheumatoid arthritis
- Swollen limb, possibly indicating lymph system blockage caused by swelling in a lymph node too far under your skin to feel
- Hardened, fixed, rapidly growing nodes, indicating a possible tumor
- Night sweats
When to see a doctor
Some swollen lymph nodes return to normal when the underlying condition, such as a minor infection, resolves. However, see your doctor if you're concerned or if your swollen lymph nodes:
- Have appeared for no apparent reason
- Continue to enlarge or have been present for two to four weeks
- Feel hard or rubbery, or don't move when you push on them
- Are accompanied by persistent fever, night sweats or unexplained weight loss
- Are accompanied by a sore throat or by difficulty swallowing or breathing
A lymph node is a small, round or bean-shaped cluster of cells covered by a capsule of connective tissue. The cells are a combination of lymphocytes — which produce protein particles that capture invaders, such as viruses — and macrophages, which break down the captured material. Lymphocytes and macrophages filter your lymphatic fluid as it travels through your body and protect you by destroying invaders.
Lymph nodes are located in groups, and each group drains a specific area of your body. You may be more likely to notice swelling in certain areas, such as in the lymph nodes in your neck, under your chin, in your armpits and in your groin. The site of the swollen lymph nodes may help identify the underlying cause.
The most common cause of swollen lymph nodes is an infection, particularly a viral infection, such as the common cold. However, there are other types of infections, including parasitic and bacterial, and other possible causes of swollen lymph nodes. They include:
- Strep throat
- Ear infections
- Infected (abscessed) tooth
- Skin or wound infections, such as cellulitis or erysipelas
- Human immunodeficiency virus (HIV) — the virus that causes AIDS
- Certain sexually transmitted infections, such as syphilis
- Toxoplasmosis — a parasitic infection resulting from contact with the feces of an infected cat or eating undercooked meat
- Cat scratch fever — a bacterial infection from a cat scratch or bite
Immune system disorders
- Lupus — a chronic inflammatory disease that can target your joints, skin, kidneys, blood cells, heart and lungs
- Rheumatoid arthritis — a chronic inflammatory disease that targets the tissue that lines your joints (synovium)
- Lymphoma — cancer that originates in your lymphatic system
- Leukemia — cancer of your body's blood-forming tissue, including your bone marrow and lymphatic system
- Other cancers that have spread (metastasized ) to lymph nodes
Other possible, but rare causes include certain medications, such as the anti-seizure medication phenytoin (Dilantin), and preventive medications for malaria.
If infection is the cause of your swollen lymph nodes and isn't treated, these complications might occur:
- Abscess formation. An abscess is a localized collection of pus caused by an infection. Pus contains fluid, white blood cells, dead tissue and bacteria or other invaders. An abscess may require drainage and antibiotic treatment. An abscess may cause significant damage if it involves a vital organ.
- Bloodstream infection (bacteremia). A bacterial infection anywhere in your body can progress to sepsis, caused by an overwhelming infection of the bloodstream. Sepsis may result in organ failure and death. Treatment involves hospitalization and intravenous antibiotics.