Causes of Swollen Lymph Nodes: What You Need to Know!

The lymph nodes are a key part of the body’s lymphatic system, which plays a crucial role in immunity. These nodes act as filters that capture and destroy harmful microorganisms, such as bacteria and viruses.

Lymph nodes can become swollen, often indicating an infection or other underlying medical condition. According to Mount Sinai, here are the primary causes of swollen lymph nodes.

1. Bacterial Infections

One of the most common causes of swollen lymph nodes is bacterial infection. Several types of bacterial infections are commonly associated with this condition:

a. Streptococcus and Staphylococcus Infections

Bacteria like Streptococcus and Staphylococcus are frequent culprits of swollen lymph nodes. For instance, a strep throat infection can cause swelling in the lymph nodes of the neck. A skin infection caused by Staphylococcus can also trigger an immune response that leads to swollen lymph nodes near the infected area.

b. Tuberculosis (TB)

Mycobacterium tuberculosis, the bacteria that cause tuberculosis, can lead to swollen lymph nodes, particularly in the neck. This condition is known as tuberculous lymphadenitis. Swelling may be chronic and initially painless, but if left untreated, the infection can spread to other organs.

c. Sexually Transmitted Infections (STIs)

Some STIs, like syphilis and gonorrhea, can cause swollen lymph nodes in the groin area as the body’s immune system responds to the bacteria causing the infection. In the early stage of syphilis, the swollen lymph nodes are typically painless, whereas in gonorrhea infections, the swelling may be accompanied by pain.

d. Cat Scratch Disease

Cat scratch disease is caused by the Bartonella henselae bacteria, transmitted through the scratch or bite of an infected cat. This infection usually causes swelling of the lymph nodes near the wound site, along with redness and pain. Systemic symptoms such as fever and fatigue may also occur.

e. Typhoid Fever

Infection by Salmonella typhi, the bacterium responsible for typhoid fever, can result in swollen lymph nodes in various parts of the body. It is often accompanied by a high fever that lasts for several days, along with an enlargement of the lymph nodes, especially in the abdominal region.

2. Viral Infections

In addition to bacterial infections, viral infections can also cause lymph nodes to swell. These viral infections can stem from various illnesses, affecting the lymphatic system as part of the body’s immune response.

a. Upper Respiratory Infections

Common viral infections like the flu or the common cold often cause swollen lymph nodes, especially in the neck and under the jaw. This is a natural immune response to respiratory infections, and the swelling typically resolves once the infection clears. Additional symptoms include fever, cough, runny nose, and sore throat. The swollen lymph nodes are usually small and tender to the touch.

b. Mononucleosis

Mononucleosis is caused by the Epstein-Barr virus (EBV) and frequently results in swollen lymph nodes in the neck, armpits, and groin. The primary symptoms of this infection include high fever, extreme fatigue, and enlarged tonsils. The lymph nodes may swell to large sizes and feel soft. Mononucleosis is often referred to as the “kissing disease” because it spreads through saliva.

c. HIV/AIDS

Human Immunodeficiency Virus (HIV) can cause persistent swelling of lymph nodes as it attacks the immune system. Swollen lymph nodes, particularly in the neck, armpits, and groin, are one of the early symptoms of HIV. Persistent lymphadenopathy, which refers to the continuous swelling of lymph nodes for over three months, may occur in later stages of the disease.

d. Measles and Rubella

The viruses responsible for measles and rubella can lead to swelling of lymph nodes, particularly behind the ears and in the neck. Measles is typically accompanied by a red rash, high fever, and cough, while rubella is generally milder but can pose a risk to pregnant women as it can cause birth defects.

e. Cytomegalovirus (CMV)

Cytomegalovirus (CMV) is another viral infection that can lead to swollen lymph nodes, especially in individuals with weakened immune systems. Symptoms are similar to those of mononucleosis, including fever, fatigue, and muscle aches. CMV spreads through bodily fluids such as saliva, blood, and breast milk.

3. Fungal and Parasitic Infections

Fungal and parasitic infections can also lead to swollen lymph nodes, although these are less common than bacterial and viral causes. However, lymph node swelling due to fungal infections should not be ignored.

a. Histoplasmosis

Histoplasmosis is a fungal infection caused by Histoplasma capsulatum. This fungus is commonly found in soils contaminated with bird or bat droppings. The infection can cause swollen lymph nodes in the lungs and surrounding areas. Symptoms include cough, fever, and fatigue, and it’s more common in individuals with weakened immune systems.

b. Coccidioidomycosis

Also known as “Valley Fever,” this fungal infection is caused by the Coccidioides fungus found in dry, dusty soils. The infection primarily affects the lungs but can also cause swollen lymph nodes. Symptoms include fever, chest pain, and chronic coughing.

c. Toxoplasmosis

Toxoplasmosis is a parasitic infection caused by Toxoplasma gondii. It typically leads to swollen lymph nodes in the neck and is transmitted through consuming undercooked meat or contact with infected cat feces. Common symptoms include mild fever, fatigue, and muscle aches.

4. Autoimmune Diseases

Autoimmune diseases, in which the body’s immune system mistakenly attacks healthy cells and tissues, can also cause swollen lymph nodes. Some autoimmune conditions that can cause this include:

a. Systemic Lupus Erythematosus (SLE)

Lupus is an autoimmune disease that causes inflammation in various parts of the body, including the lymph nodes. Swollen lymph nodes are often accompanied by joint pain, skin rashes, and fatigue. Lupus tends to flare up and may be triggered by stress or infection.

b. Rheumatoid Arthritis (RA)

Rheumatoid arthritis (RA) is an autoimmune disease that affects the joints and may cause lymphadenopathy, swelling of the lymph nodes. This occurs due to chronic inflammation in the body. Common symptoms of RA include joint pain, morning stiffness, fatigue, and in some cases, swollen lymph nodes in areas like the neck, armpits, or groin.

5. Cancer

Cancer is another serious cause of swollen lymph nodes. In some cases, swollen lymph nodes may be one of the first signs of cancer. Types of cancer that can cause lymph node swelling include:

a. Lymphoma

Lymphoma is cancer that originates in the lymphatic system, and there are two main types: Hodgkin lymphoma, characterized by the presence of Reed-Sternberg cells, and non-Hodgkin lymphoma, which is more common. Swelling of lymph nodes without pain is common, and it is often accompanied by fever, night sweats, and unexplained weight loss.

b. Leukemia

Leukemia is a cancer of the blood that can cause swollen lymph nodes due to the overproduction of abnormal white blood cells. Symptoms include extreme fatigue, frequent infections, and easy bruising or bleeding. Treatment for swollen lymph nodes in leukemia may involve complex medical intervention.

c. Cancers from other parts of body

Cancer from other organs, such as head & neck region, breast or lung cancer, can also spread to the lymph nodes, especially in the armpit or neck area. This is usually detected during medical exams and may be accompanied by symptoms of the primary cancer, such as a lump in the breast or chronic cough.

6. Medication Side Effects

Certain medications can cause swollen lymph nodes as a side effect. Some medications, such as anti-seizure drugs like phenytoin or biologic drugs for autoimmune diseases, can lead to lymphadenopathy.

Conclusion

Swollen lymph nodes can be caused by various factors, ranging from mild infections to serious conditions such as cancer. That’s why it’s important to identify the underlying cause through a thorough medical examination. If the swelling doesn't go away, it's strongly recommended to seek medical attention at a hospital.

For consultations, you can also visit IHH Healthcare Malaysia. The hospitals under IHH Healthcare Malaysia are ready to assist you—whether it’s for a consultation or a full medical check-up. So, there’s no need to worry—get checked today!