What causes swollen lymph nodes?

The lymph nodes, an essential part of the lymphatic system, can become inflamed for a variety of reasons, the most common being the presence of an infection. In other words, swollen glands are usually a sign that your body’s defenses are at work.

The location of swollen nodules depends on the site of infection. For example, neck nodules can become inflamed in cases of flu, tonsillitis or otitis.

In many cases, the inflammation goes away on its own within a few days once the infection is over. However, if the area is red and hot, or if you have a fever, it is best to see a doctor, as well as if the lump is hard and immobile (it can usually be moved with your fingers).

Although the term adenopathy or lymphadenopathy exactly refers to a non-specific disorder of the lymph nodes, it is very common for these terms to be used to refer in a general way to the inflammation of the lymph nodes without paying attention to the cause.



The most common cause of swollen glands is an infection, whether bacterial, viral, fungal or parasitic. Lymph is filtered into lymph nodes where there is a connective tissue network filled with lymphocytes that collect and destroy germs and toxins, triggering a humoral or cellular immune response that often causes inflammation.

autoimmune diseases

Other causes are problems and illnesses related to the immune system, such as some allergic reactions, sarcoidosis, rheumatoid arthritis, or lupus erythema.systemic killed.


The presence of a tumor can also be a cause of adenopathy. Among those that cause inflammation in the lymph nodes, we can distinguish between primary tumors, such as Hodgkin’s lymphoma, non-Hodgkin’s lymphomas, and some types of leukemia, and secondary tumors, such as Virchow’s lymphoma, neuroblastoma, or metastasis from another tumor.

Side effects and drug reactions

Some medications can cause adenopathy as a side effect, such as phenytoin (or diphenylhydantoin, an antiepileptic), or by a hypersensitivity reaction, such as allergic reactions to thioamides (used primarily to control Basedow’s disease) and aminosalicylic acid (mesalazine, antituberculosis).


Bites and pecks from some animals can also cause the glands in the area to swell, especially some snakes such as the taipan, black mamba, coral snake, and some snake species. This is due to the action of the inoculated venom, but a bite from any animal can produce a secondary infection that also causes inflammation of the lymph nodes.

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Location and relationship to the cause

Lymph nodes or lymph nodes are part of the lymphatic system and are distributed throughout the body in clusters in the form of clusters. It is estimated that there are around 600 lymph nodes in the human body and they appear in the armpits, groin, neck, mediastinum and abdomen. Everyone can become inflamed, but the most visible, due to their proximity to the skin surface, are the nodules in the groin, armpits and neck.

Usually the nodes are inflamed locally and this is why we can deduce where the problem could be depending on the area where they appear:


In the neck, swollen glands may appear on the sides, behind the ears, or under the jaw. They would indicate an upper respiratory tract infection such as tonsillitis, colds and flu, and infections in other areas of the head (otitis, dental infections, etc). Nodules in this area can also become inflamed from lesions and tumors in the area.


The nodes in the armpits can become swollen due to injuries and infections in the upper extremities and, less often, it can be related to lymphomas or breast cancer.


In the groin are located inguinal and femoral ganglia. They can be inflamed by injuries to any part of the leg and genitals, as well as infections in these regions of the body. They can also become inflamed, although this is rare, due to testicular cancer and the appearance of lymphomas.


The supraclavicular lymph nodes (above the collarbone) may be swollen due to infections and tumors in the chest and abdomen, but also in the neck.

generalized adenopathy

Lymph nodes are usually locally swollen because they are the filtering lymph nodes where the lymph vessels in a given area converge. If swollen nodes appear in two or more areas, we can speak of generalized adenopathy (or generalized lymphadenopathy). Among the possible causes we can find:

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viral infections: measles, rubella, chickenpox, mumps, infectious mononucleosis (Epstein-Barr virus), cytomegalovirus, infectious hepatitis, AIDS Bacterial infections: tuberculosis, brucellosis, syphilis, streptococcal pharyngitis, Lyme disease parasites: toxoplasmosis, African trypanosomiasis fungal infections: histoplasmosis Side effects of phenytoin and other medicines or the MMR vaccine (measles-mumps-rubella) Some types of leukemia and lymphomas


The symptoms of adenopathy are very varied and largely depend on the cause. We can even find patients with totally asymptomatic lymph nodes or exactly the opposite, with very painful and swollen nodes.

Perhaps the most important are the symptoms of the underlying disease causing the adenopathy, as they are often more clinically relevant. For example, the presence of fever and earache could be a sign of an ear infection that needs to be treated and that is causing the glands in the neck to swell.

when to go to the doctor

The most common is that swollen glands are not a concern however as has been pointed out some of the causes can be serious so they should be monitored. You should always go to the doctor, especially if the lumps remain for more than a week, fever, sweating, joint pain, or weight loss appear.

You should also see your doctor when the area where the swollen nodules appear is hot and red, if the nodules are very swollen and larger than 1 cm in diameter, are too hard, or cannot be moved with your fingers. The doctor should be told if there was an infection that may have caused the swelling, but the lumps have not returned to their normal state after the infection has subsided.

Tests and analysis

Given the wide variety of causes that can cause adenopathy, diagnostic tests to determine the cause are similarly varied. On some occasions, as in the case of infections, the diagnosis of the cause can be based on the diagnosis of the infection without specific tests. But when a conclusive result is not achieved, a thorough examination of the patient, including blood analysis, is usually performed.

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If blood tests and examination of the patient do not identify the cause, or if swollen glands persist, ultrasound, biopsy, or both are usually used to accurately determine the structure of the node and confirm or rule out cancer.


Treatment focuses on treating the cause and there is no treatment specifically aimed at swollen glands. For example, if there is an infection, treatment is directed at ending the infection, or if there is cancer, treatment is directed against the cancer. However, anti-inflammatories and pain relievers may be prescribed to reduce inflammation and pain.


In case of infection, the nodules may remain swollen for a long time after the infection has healed, especially in children. If the underlying infection is left untreated, an abscess and infection of the surrounding tissue.

If the nodes become too large, they can compress nearby structures, which in some cases can be severe and require emergency surgery. For example, they can compress blood vessels and nerves.


Examination of the lymph nodes in the neck Location of the lymph nodes in the neck and head Swollen node at the base of the neck Lymph travels through the lymph vessels and nodes.

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