What can cause enlarged lymph nodes in the groin?

Lymph nodes are an important part of your immune system. They have special cells that can help fight off an infection. When your lymph nodes are swollen, it often means your body is fighting an illness. However, you might still require treatment as your body can’t always do the job on its own. 

The lymph nodes in the groin are called the inguinal lymph nodes. If these are enlarged, there are many possible causes besides infection, including chronic conditions and prescription medications. Depending on what’s behind the swelling, a doctor can recommend appropriate treatment. 

Common causes of enlarged lymph nodes include:

Infections

Infection from bacteria or viruses is a common cause of enlarged lymph nodes in the groin. A healthcare professional can test for an infection and determine what type of bacteria is behind it.

Groin lymph node swelling might signal a sexually transmitted infection (STI) such as:

• Lymphogranuloma venereum: This infection results from a strain of the Chlamydia trachomatis bacterium.
• Syphilis: This infection is due to the Treponema pallidum bacterium. While early-stage syphilis might not lead to lymph node symptoms, it can cause swollen lymph nodes if it progresses to the secondary stage.
• Chancroid: This infection results from the bacterium Haemophilus ducreyi.

Fungal infections or infections from viruses, such as HIV and herpes simplex, can also cause lymph node swelling in the groin.

Lymphedema

Inflammation or damage to the inguinal lymph nodes can lead to lymphedema, a condition where the lymph node cannot drain fluid in certain body parts. Lymphedema may result from an infection of the lymph node or from cancer in the lymph node. 

In rare occasions, it may be due to lymphatic filariasis, a parasitic infection of the lymph system.

Cancer

Sometimes, enlarged lymph nodes in the groin can be a sign of cancer. If cancer is the cause of swelling in your inguinal lymph nodes, it might have spread from elsewhere in your body. It might also have started in the lymph nodes.

Types of cancer that might spread to your groin’s lymph nodes include:

• vulvar cancer, which occurs on the skin surrounding the urethra and vagina
• penile cancer, which occurs on the penis
• anal cancer, which occurs in the anal canal

According to the American Cancer Society, swelling of lymph nodes is often not from cancer but from another cause.

Autoimmune conditions

An autoimmune condition can also result in swelling of the lymph nodes. Common examples include lupus and rheumatoid arthritis (RA). 

You might also experience swelling only in the lymph nodes of the groin, or you may have generalized lymphadenopathy, where at least two lymph nodes not close to each other are enlarged. 

Medication use

Some prescription medications can also cause enlarged lymph nodes. They include high blood pressure and seizure medications, such as:

• atenolol (Tenormin)
• captopril (Capoten)
• hydralazine (Apresoline)
• phenytoin (Dilantin)
• primidone (Mysoline)

Enlarged lymph nodes can also be a potential side effect of many other medications, including the antibiotic sulfamethoxazole-trimethoprim (Bactrim) and the anti-parasitic medication pyrimethamine (Daraprim). 

If you experience this side effect, consider speaking with a healthcare professional. They may be able to recommend an alternative medication. 

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Treatment options

Common examples of conditions that cause enlarged lymph nodes are listed below, along with their treatment plans.

Cancer

Treatment for cancer depends on the type of cancer and the stage. Your treatment options might be different if the inguinal lymph node is the primary site of the cancer or if your cancer has spread to the lymph nodes. 

In general, people might have one or a combination of treatments, such as:

• surgery
• chemotherapy
• radiation
• immunotherapy
• hormone therapy
• targeted therapy

Infections

Doctors often treat an infection, such as an STI, with specific medications:

• Lymphogranuloma venereum: doxycycline (Vibramycin) and azithromycin (Zithromax)
• Syphilis: benzathine penicillin (Bicillin L-A)
• Chancroid: azithromycin (Zithromax), ceftriaxone (Rocephin), and erythromycin (Erythrocin)

Autoimmune conditions

A healthcare professional can put together a treatment plan to help you manage an autoimmune condition. It may include medications, physical or occupational therapy, or surgery.

First-line medications for lupus and rheumatoid arthritis include nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil) and naproxen (Aleve), as well as corticosteroids like prednisone (Rayos). 

Other medications to treat lupus or rheumatoid arthritis are as follows:

• Lupus: Medications for lupus include antimalarial drugs such as hydroxychloroquine-sulfate (Plaquenil), chloroquine phosphate (Aralen), and BLyS-specific inhibitors such as belimumab (Benlysta).
• Rheumatoid arthritis: Several medications are available for RA, including disease-modifying antirheumatic drugs (DMARDs) such as methotrexate (Rheumatrex) and sulfasalazine (Azulfidine).

When should you speak with a doctor?

If you have unexpected swelling of lymph nodes in the groin, consider speaking with a doctor. They can help diagnose the underlying cause.

Treating the cause early can usually prevent symptoms from getting worse. With some conditions, such as syphilis, symptoms might appear to go away, but the infection may remain in the body, causing serious problems later. 

Summary

Enlarged lymph nodes in the groin can have many different causes, including:

• infection
• cancer
• medication use
• autoimmune disorders

Getting a diagnosis of what’s causing the swelling can help you get the most suitable treatment.

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