Swollen Groin Lymph Nodes Causes and Conditions

Enlargement of lymph nodes is not uncommon and often goes unnoticed by most people. Usually it is a temporary swelling often associated with immune activity as the body fights off an infection. The swelling may be very minor and resolve on its own without any need for medical treatment. However, there are times when lymph node swelling is persistent and very large requiring medical intervention to either treat the underlying cause or at times even surgically removing the lymph nodes.

Why do groin lymph nodes swell?

The lymph nodes are part of the lymphatic system, a network of channels that drains tissue fluid away from different parts of the body and also trap and destroy any invading microbes like bacteria. The lymphatic vessels are the conduits while the nodes are the filtering points. The lymph nodes are filled with immune cells that act rapidly to neutralize any threat to the body. When active, it can cause the lymph nodes to swell and for this reason an enlarged lymph node is usually associated with an infection.

The neck, armpit and groin lymph nodes are probably the most commonly swollen nodes but this does not always mean that there is a serious problem. The body’s ability to defend itself is unmatched by any advance in medical science although it is not completely foolproof. Most people are concerned about the swelling of groin lymph nodes as it may be a sign of a sexually transmitted disease (STD). While this is often true, these lymph nodes can also swell for other reasons which may not be associated with infections.

Lymph nodes that are large and growing in size, irrespective of the feel, should always be investigated by a medical practitioner even if there are not other symptoms present.

Causes of Enlarged Groin Lymph Nodes

Although there are lymph nodes distributed throughout the body and pelvic region, most of us consider the inguinal lymph nodes as being the groin lymph nodes. These nodes lie in the inguinal crease, a skin fold that forms where the torso joins the lower limbs. There are two layer of these inguinal lymph nodes – superficial and deep. It is important to differentiate between an enlarged lymph node or an abscess which may occur with an infection. Many people mistaken an abscess for a swollen lymph node and vice versa.

Groin and Systemic Infections

Most of the time enlarged lymph nodes are associated with an infection typically where the pathogen enters the body at the groin region. The presence of the genitalia often mean that groin lymph node swelling is due to sexually transmitted disease. However, these lymph nodes can also swell due to infections that do not involve the genitalia or even with systemic infections.

  • Sexually transmitted diseases (STDs) such as gonorrhea, syphilis and genital herpes.
  • Bacterial infections of the skin (impetigo) and underlying tissue (cellulitis) and systemic bacterial infections like the bubonic plague.
  • Viral infection like infectious mononucleosis and HIV (human immunodeficiency virus) infection.
  • Protozoal infections like toxoplasmosis.
  • Lymphadenitis is inflammation of the lymph nodes which is often due to viral or bacterial infections.

The swollen groin lymph nodes may also be accompanied by swollen nodes elsewhere on the body, like the neck and axillae (armpits). This is a common occurrence in HIV infection where these lymph nodes become very large usually as the infection progresses. Many patients may opt for surgical removal of these nodes.

Malignant Tumors

Many types of malignancies (cancers) cause swelling of the lymph nodes as the immune cells attempt neutralize the cancer cells. Often these cancerous cells travel through the lymphatic system and can sometimes cause cancer of the lymph nodes themselves (secondary spread/metastasis). Cancer can arise within the lymph node itself (primary).

  • Cancer of the organs in the groin or pelvic region may cause enlargement of the inguinal lymph nodes, such as cancer of the vulva (women) and anal cancer.
  • Leukemia is a cancer of the blood-producing tissue which affects both the bone marrow and lymphatic tissue.
  • Lymphoma is cancer of the lymph nodes which is classified as Hodgkin’s or non-Hodgkin’s.
  • Melanoma is a type of skin cancer which can occur anywhere in the body.

Since cancers can very easily spread to localized lymph nodes before spreading further across the body, the lymph nodes are closely monitored in cancer patients and even removed when the tumor is excised. The spread of cancerous cells to the regional lymph nodes is an important diagnostic feature to determine the severity of the cancer and risk of the cancer spreading to other sites in the body.


Certain drugs can cause lymph node swelling as a side effect. This is not a common side effect. It is mainly seen with drugs that target the lymphatic tissue like certain leukemia drugs or other anti-cancer medication (chemotherapy). Other drugs like certain antibiotics, gout medication, epilepsy and anti-psychotic drugs can cause lymph node swelling, not only of the groin lymph nodes. Never stop any medication if enlargement of the lymph nodes occur as a side effect unless advised so by a medical professional.


It is not uncommon for there to be lymph node swelling after the administration of vaccines. The immune cells that reside within lymph nodes become active after the administration of certain vaccines as it ‘learns’ how to target and neutralize specific pathogens. There may also be mild infectious symptoms following a vaccine although it is not due to an actual infection. Lymph node swelling is usually temporary in these cases. It is common with childhood immunizations and is not a cause for concern.

Systemic Diseases

Certain systemic diseases that are not infectious in nature can cause lymph node swelling. It is seen in conditions like rheumatoid arthritis and systemic lupus erythematosus. Lymph node swelling in these cases are more often associated with autoimmune diseases where the immune system attacks the body’s own tissue due to some dysfunction. Malaise and fever may also occur with some autoimmune diseases and it is therefore mistaken at times for an infection.

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