What causes painful lymphadenitis? Understanding the Underlying Reasons

October 2, 2025 •

4 min read

Painful lymphadenitis, the medical term for tender and swollen lymph nodes, is most often caused by an infection that has spread from a nearby area. Understanding the root cause of this condition is essential for proper treatment and effective recovery.

Quick Summary

Painful lymphadenitis results from an underlying infection—most commonly bacterial or viral—that inflames the lymph nodes as they filter and fight off pathogens. Other potential causes include inflammatory conditions and, in rare instances, cancer.

Key Points

Infections are the main cause: Bacterial and viral infections are the most common triggers of painful lymphadenitis as the immune system activates.
Localized vs. Generalized: Painful, swollen lymph nodes may be localized (near an infection) or widespread, depending on the cause.
Pain is a key sign: Tender and painful swelling often indicates an active infection, as opposed to the typically painless swelling seen with chronic issues like cancer.
Autoimmune conditions can trigger it: Diseases like lupus and rheumatoid arthritis can cause the immune system to cause inflammatory lymph node swelling.
Diagnosis is crucial: Determining the cause of painful lymphadenitis requires medical evaluation, which may include a physical exam, blood tests, and potentially a biopsy.
Treatment depends on the cause: The underlying cause, whether a bacterial infection, viral illness, or another condition, dictates the appropriate treatment, from antibiotics to simply waiting for the infection to clear.

The Body's Defense System: A Closer Look at Lymph Nodes

Lymph nodes are small, bean-shaped structures that are a vital component of the immune system. Acting as filters, they trap viruses, bacteria, and other foreign invaders, preventing them from spreading further through the body. When an infection is detected, the nodes rapidly produce white blood cells, causing them to swell and become tender or painful. This reaction is known as lymphadenitis, a telltale sign that your body's immune system is actively at work.

Primary Causes of Painful Lymphadenitis

Infectious Origins

Bacterial Infections Infections caused by bacteria are one of the most common reasons for painful lymphadenitis. When a local skin infection, sore throat, or wound occurs, bacteria can travel to the nearest group of lymph nodes, triggering an inflammatory response. Key examples include:

Staphylococcus aureus and Streptococcus pyogenes: These bacteria are responsible for the vast majority of acute bacterial lymphadenitis cases, often spreading from a nearby skin or soft-tissue infection.
Cat-scratch disease (Bartonella henselae): This results from a scratch or bite from an infected cat and can cause localized, painful lymphadenitis, typically in the armpit or groin.
Other infections: Less common but serious bacterial causes can include syphilis, tuberculosis, or tularemia (rabbit fever).

Viral Infections Viruses are also frequent culprits, causing generalized or localized lymph node swelling as the body mounts an immune defense.

Common Respiratory Viruses: Viruses like the common cold or flu can cause painful lymphadenitis in the neck.
Mononucleosis (Epstein-Barr virus): Often referred to as "mono," this viral infection can lead to significantly swollen and painful lymph nodes, especially in the neck.
HIV: In its early stages, an HIV infection can cause generalized lymphadenopathy (swollen lymph nodes) throughout the body.
Mesenteric Lymphadenitis: This specific form affects the lymph nodes in the abdomen, often caused by viral gastroenteritis, or "stomach flu".

Fungal and Other Infections While less common, certain fungal infections can also lead to painful lymphadenitis, particularly in immunocompromised individuals. Conditions like toxoplasmosis, a parasitic infection, can also trigger this response.

Inflammatory and Autoimmune Conditions

Sometimes, painful lymphadenitis is a symptom of a more systemic issue related to inflammation or an autoimmune response. In these cases, the immune system mistakenly attacks healthy cells, causing a widespread inflammatory reaction that includes the lymph nodes. Conditions include:

Lupus: A chronic disease that causes widespread inflammation and can affect the joints, skin, kidneys, and lymph nodes.
Rheumatoid Arthritis: An autoimmune disorder causing inflammation in the joints, which can also trigger lymphadenopathy.
Sarcoidosis: This disease involves the growth of tiny collections of inflammatory cells (granulomas) in different parts of the body, most often the lungs and lymph nodes.

Other Potential Causes

Though significantly less common, other factors can cause swollen, and sometimes painful, lymph nodes:

Malignancy (Cancer): Cancers such as lymphoma, leukemia, or metastatic cancer can cause lymph nodes to enlarge. Unlike typical infections, these are often painless or only slowly growing, but can sometimes cause tenderness. A node that feels hard, fixed, and doesn't move should be evaluated by a doctor.
Medications: Certain medications, including some for seizures or heart conditions, can cause swollen lymph nodes as a side effect.

When Pain Provides a Clue

Painful lymphadenitis is a key characteristic that can help distinguish between different causes. Here is a comparison of signs that provide valuable insight into the potential trigger:


Feature	Acute (Painful) Lymphadenitis	Chronic (Painless) Lymphadenadenopathy
Onset	Sudden	Slow and gradual
Sensation	Tender, sore, or painful to the touch	Often painless
Texture	Soft, movable, may feel rubbery	Hard, fixed, or matted together
Accompanying Symptoms	Fever, chills, sore throat, local infection	Night sweats, unexplained weight loss, fatigue
Underlying Cause	Bacterial or viral infections	Malignancy, autoimmune diseases

Diagnosing the Cause of Painful Lymphadenitis

To accurately determine what causes painful lymphadenitis, a healthcare provider will conduct a thorough examination and may order additional tests. The diagnostic process typically includes:

Physical Exam and Medical History: The doctor will check the size, tenderness, and location of the swollen lymph nodes. They will also inquire about any recent infections, travel, or animal contact.
Blood Tests: These can help identify the presence of a widespread infection or an underlying autoimmune condition.
Cultures: If a nearby wound or abscess is present, a sample of the fluid can be cultured to identify the specific germ responsible.
Biopsy: In cases where the cause is not clear or a malignancy is suspected, a tissue sample from the lymph node may be taken and examined under a microscope.

The Path to Recovery: Treating Painful Lymphadenitis

Treatment for painful lymphadenitis is entirely dependent on the root cause discovered during diagnosis. Effective strategies include:

Antibiotics: For bacterial infections, a course of antibiotics is typically prescribed. It is crucial to complete the full course of medication, even if symptoms improve quickly, to ensure the infection is fully eradicated.
Antivirals: In some cases, such as with certain viral infections, an antiviral medication may be necessary.
Symptom Management: Over-the-counter pain relievers like ibuprofen can help manage the pain and swelling. Applying a warm, wet compress to the affected area can also provide relief.
Abscess Drainage: If the lymph node becomes filled with pus (forms an abscess), a doctor may need to drain it surgically.
Treating the Underlying Condition: If an autoimmune disorder is the cause, treatment will focus on managing that condition. For information on specific autoimmune disorders, reliable resources such as those from the University of Rochester Medical Center can be very helpful(https://www.urmc.rochester.edu/encyclopedia/content?contenttypeid=134&contentid=80).

Conclusion

While the sight of a swollen, painful lump can be alarming, painful lymphadenitis is most commonly a sign that your immune system is successfully fighting an infection. By understanding the various potential causes, you can recognize when it's appropriate to manage the symptoms at home and when to seek professional medical advice. Always consult a healthcare provider for a proper diagnosis, especially if the swelling is persistent, growing, or accompanied by more serious symptoms.

Frequently Asked Questions

Lymphadenopathy is the general term for any swollen or enlarged lymph nodes. Lymphadenitis is a specific type of lymphadenopathy that indicates the lymph nodes themselves have become infected and inflamed, which often makes them painful.

You should contact a healthcare provider if your lymph nodes feel hard, are fixed in place, continue to enlarge, last longer than two weeks, or are accompanied by fever, night sweats, or unexplained weight loss.

While cancer can cause swollen lymph nodes, it is a less common cause. Swelling due to cancer is typically slow, painless, and the nodes often feel hard and immobile. Painful swelling is more indicative of infection or inflammation.

During a throat infection, such as strep throat, the lymph nodes in your neck swell up as they work to filter out the bacteria. The pain is caused by the rapid expansion and inflammation of the nodes as they fight the infection.

If the underlying cause is an infection, home care can include applying a warm compress to the area and taking over-the-counter pain relievers, such as ibuprofen. Rest and adequate fluid intake are also important for recovery.

In rare cases, severe swelling of the lymph nodes in the neck can interfere with breathing or swallowing. This is a serious symptom that requires immediate medical attention.

Painful lymph nodes in the armpit (axillary lymphadenitis) often indicate an infection or injury in the hand, arm, or nearby chest area. Less commonly, it can be a sign of cat-scratch disease or, in rare cases, a malignancy.