Lymph nodes are small kidney-shaped organs that are a crucial part of your lymphatic system, which in turn is a component of your body’s immune system. Their key function is to fight off infection with the help of white blood cells called lymphocytes contained within the lymph nodes themselves.
Lymph nodes act as filters, trapping bacteria, viruses, and other germs that pass through them along with the lymph. Thus, they prevent these germs from infecting other areas of your body.
However, in doing so, your lymph nodes can get larger when they call upon the lymphocytes for defense. These white blood cells multiply rapidly, causing your lymph nodes to become enlarged or swollen. The medical term for swollen lymph nodes is lymphadenopathy.
Another function of lymph nodes is to filter the leaked-out lymph, which is a clear fluid inside your lymphatic system. This system resembles channels that run throughout your body in parallel with your veins.
Where are lymph nodes located in your body?
There are up to 800 lymph nodes scattered in clusters throughout your body. Each cluster drains a specific area of your body.
Lymph nodes are present as a pair (on both sides of your body) in areas where blood vessels converge on your body. The most important ones include:
- Neck (cervical lymph nodes).
- Behind your ears.
- Axilla, or armpit (axillary lymph nodes).
- Thorax (chest).
- Groin (inguinal lymph nodes).
Symptoms of swollen lymph nodes
Normal lymph nodes are under one centimeter in diameter, about the size of a pea or a grape, with some exceptions. For instance, the normal size of the lymph nodes in the groin is less than 1.5 centimeters. They are also not palpable, meaning you cannot feel them unless you’re a skinny person. But when these nodes swell, you can feel them with your fingers.
Lymph nodes swollen from an infection or inflammation usually feel as soft, little rubbery lumps. They might also be tender to touch. They are well-defined and moveable when pushed.
In contrast, having unusually large bumps that are harder in consistency, matted, and fixed, may indicate cancer.
Moreover, when infection or inflammation is the cause, lymph nodes will swell near the infection site. For instance, strep throat causes your neck’s lymph nodes to swell. The medical term for this localized lymph node swelling is localized lymphadenopathy.
However, a cancerous process tends to involve more than one area of lymph nodes – a condition called generalized lymphadenopathy.
Causes of swollen lymph nodes
Potential causes of swollen lymph nodes include both common and uncommon infections, cancers, autoimmune disorders and a few rare causes.
- Common cold or flu: the most common viral causes of swollen lymph nodes.
- Strep throat: the most common bacterial cause of swollen lymph nodes.
- Tonsillitis: inflammation of the tonsils.
- Tooth abscess, or tooth infection.
- Ear infections.
- Infections of the salivary glands: the mumps virus most often infects a specific salivary gland.
- Measles: a contagious viral infection which causes lymph node swelling in the back of your neck.
- Mononucleosis: a viral infection that causes a sore throat along with swollen lymph glands in your neck and armpit.
- Human immunodeficiency virus (HIV): the virus that causes AIDS.
- Bronchitis: inflammation of the bronchi secondary to an infection, which are the two breathing tubes in your lungs.
- Tuberculosis: a bacterial infection that causes lymphadenopathy, largely seen in developing countries.
- Toxoplasmosis: a parasitic infection resulting from eating infected undercooked meat, drinking contaminated water, or handling infected cat feces (poop) or soil.
- Cat scratch fever: a bacterial infection from a cat scratch or bite.
- Some sexually transmitted infections, such as syphilis and lymphogranuloma venereum, both of which are caused by bacteria.
- Leukemia: a cancer of the blood and bone marrow that produces abnormal white blood cells.
- Lymphoma: a cancer that develops in your lymphatic system.
- Other cancers that spread to lymph nodes.
An autoimmune disorder is one in which your body's immune system harms your own tissues and organs.
- Lupus: targets joints, kidneys, skin, heart, blood cells, lungs, and lymph nodes.
- Rheumatoid arthritis: affects the tissue surrounding your joints (synovium).
Certain medications, such as:
- Anti-seizure medications: phenytoin (Dilantin), carbamazepine, and primidone.
- Medications to treat gout.
- Antibiotics: cephalosporins, penicillin, sulfa drugs, etc.
- Medications for preventing malaria.
- Lymphadenitis, in which there is inflammation in response to a lymph node infection.
When should you see a doctor?
When a virus or a bacterium is the culprit, swollen lymph nodes will go back to their original size as the bug clears up. With that said, enlarged lymph nodes become a cause for concern if they:
- Last for more than two weeks.
- Continue to grow bigger.
- Are hard, stone-like and don't move when pushed under the skin.
- Involve two or more distinct anatomical body regions.
- Have emerged without any apparent cause.
- Are accompanied by other symptoms like chronic fever, drenching night sweats, noticeable and unexpected weight loss, or enlarged liver and spleen, etc.
- Are present in the area above your collarbone.
- Occur in old age.
Screening for swollen lymph nodes
Usually, there’s no need for any screening in straightforward cases. However, doctors run tests if they suspect something serious or some harmless condition fails to explain your symptoms.
The most common tests used for screening of enlarged lymph nodes include ultrasound, computed tomography (CT) or magnetic resonance imaging (MRI) scans, and biopsy.
A biopsy is a short procedure that involves removing one or two of the affected lymph nodes with a scalpel. Your doctor then sends the sample to the lab for examination under a microscope. The pathology technician will look for cancerous cells in the biopsied sample.
Treatment of swollen lymph nodes
When infection is the cause, lymph node swelling will usually fade as your body heals.
In addition, addressing the underlying cause is imperative to help alleviate the swelling. Likewise, home remedies can also provide some relief.
Treatment of the underlying cause:
- Antibiotic therapy for bacterial infections.
- Antiviral therapy for viral infections, except for the common cold, which can improve with symptomatic treatment and home remedies.
- Surgery and/or radiation therapy and/or chemotherapy for cancers.
- Immune therapy and steroids for autoimmune conditions.
- Discontinue the culprit medicines.
- Over-the-counter painkillers, such as acetaminophen or ibuprofen, for pain.
- Warm wet compresses to ease inflammation and pain.
- Plenty of fluids.
- Resting to speed up recovery.
Maini, R., & Nagalli, S. (Updated November 25, 2021). Lymphadenopathy. In: StatPearls Treasure Island (FL): StatPearls Publishing.
Ozdowski, L., and Gupta, V. (Updated May 8, 2022). Physiology, Lymphatic System. In: StatPearls. Treasure Island (FL): StatPearls Publishing.
Mohseni, S., Shojaiefard, A., Khorgami, Z., Alinejad, S., Ghorbani, A., and Ghafouri, A. (2014). Peripheral lymphadenopathy: approach and diagnostic tools. Iranian Journal of Medical Sciences.