Swollen Lymph Nodes in the Armpit

Last updated: May 27, 2021

Contributed by:
Richard Honaker M.D.
Primary Care Physician
View Full Profile

Swollen lymph nodes in the armpit could be an indication of an illness, injury or infection in the body. 


Armpits are not one of the more glamorous areas of the body. They are often hairy, sweaty and smelly. Yet it is important to pay attention to any significant changes in this often overlooked area of your body. A lump or bump could mean a swollen lymph node. 




Lymph nodes are oval-shaped pieces of lymphatic tissue that play an important role in your immune system. Swelling of your lymph node in any part of your body could indicate an injury, illness or infection. While a swollen lymph node could be the cause of something relatively harmless, it could also be an indication of something much more serious. 


What are Lymph Nodes?


Lymph nodes are small bean-shaped tissues that act as filters within the lymphatic system. 


Your lymphatic system plays an important role in your immune system. Lymph vessels work together within a network to draw fluid, waste, viruses and bacteria from the body. 


Lymph Vessels

Source: Canva


The lymph vessels are formed together in a complex pathway in the body which draws lymph fluid away from the body’s capillary walls and towards the chest where it is absorbed into the bloodstream. 


Lymph vessels run along the body much like your veins although even the biggest lymph vessel is smaller than your largest vein. 


The lymph vessels gather fluid throughout the body and in most cases it is filtered through several nodes. For example, if a lymph node is located under the armpit it is filtering lymph fluid from the fingers as well as the arms. 


Lymph Fluid


The fluid that flows through the lymph vessels also plays an important role in your immune system. As the fluid flows through the lymph vessels it removes impurities such as bacteria and carbon dioxide. It also carries nutrients such as oxygen and infection-fighting white blood cells called lymphocytes throughout the system. 


There are two main types of lymphocytes:


  • B lymphocytes (B cells): These cells protect the body from bacteria and viruses by making antibodies. 
  • T lymphocytes (T cells):These cells either boost the activity of other immune cells or destroy germs and abnormal cells.  


Lymph Nodes

Source: Canva


Lymph nodes are found along the lymph vessels similarly to beads along a necklace chain. The nodes are small bean-shaped tissue. They work as a filter to remove the body’s impurities that are in the body’s muscle tissue, outside of the bloodstream. 


There are approximately 600 lymph nodes in the body that are located at intervals along the lymph vessels. Some lymph nodes are close to the skin’s surface, while others are located deep within the body. 


The lymph nodes are important as they remove impurities such as viruses, bacteria and even cancer cells from the lymph fluid as it passes through the node. The nodes are able to do this because they contain immune cells that help your body to break down infection in the body. The fluid travels slowly through the body, passing through one or more nodes before it reaches its final destination in your chest. 


Swollen Lymph Nodes in the Armpit


Lymph nodes will swell as a reaction to an illness, infection or injury. You may notice that your doctor will routinely feel the lymph nodes in your neck, behind your ears and under your jaw during a routine exam. This is because lymph nodes will swell in response to infection in the area they are located. Any upper respiratory infection can cause lymph nodes to swell in this area. 


When the swollen lymph node is located under the armpit it can be a sign of an illness, infection or injury in that general area. In their normal state lymph nodes are not able to be felt. When swollen lymph nodes can swell from the size of a pea to as large as the size of a cherry. In general, lymph nodes more than 1 cm in diameter are considered to be ‘abnormal’. 


Why would Lymph Nodes in the Armpit Swell? 

Source: Canva


Although swollen lymph nodes in the armpit may seem scary, they are often simply the result of a benign infection. Infection that spread to the lymph nodes are usually caused by bacteria, fungus or a virus. 


While swollen lymph nodes are usually the result of an infection, they can also indicate other medical conditions as well. While swollen lymph nodes are more common in the neck, behind the ear and under the jaw, they can also occur in the armpit. 


Swollen lymph nodes in the armpit can be a result of: 


  • Adverse reactions to vaccinations


  • Systemic lupus erythematosus (an autoimmune disease that targets your joints and organs)


  • Lymphoma


  • Leukemia


Swollen lymph nodes can also be the result of an injury in the area. Certain injuries can cause scar tissue in the area which can make it difficult for the lymph nodes to properly filter the lymph fluid. In these cases surgery may be required to resolve the issue. 


Other possible Diagnosis

Source: Canva


Swollen lymph nodes are not the only reason for a bump in the area. There are many possible explanations for lumps and bumps under the armpit. No matter what you suspect the lump to be, it is important to have the bump checked by your physician. 


Breast Cancer


Armpit lumps can occur at any time, but in women it can be a sign of breast cancer. It is important to perform monthly self-exams and to report any findings to your doctor right away. 

During your menstrual cycle your breasts may change and feel more or less lumpy. The best time to perform a self-exam is about three days after your last period. Keeping your checks consistently at the same time each month is ideal. 


close up image of folliculitis

source: Canva

Folliculitis occurs when the hair follicle becomes compromised and inflamed. This often occurs as a result of shaving, especially dark and coarse hair. Folliculitis is easily mistaken for acne because it often causes red bumps that may or may not become filled with pus. Folliculitis can be a mild irritation or become inflamed and tender to the touch. 


Hidradenitis suppurativa 


This painful, long-term skin condition occurs when there is inflammation near apocrine glands of hair follicles in the skin become clogged leaving behind painful boil-like lumps that will fill with pus, leak and may become infected. 




Fibroadenomas are  noncancerous fibrous tissue growth. It is the most common type of non-cancerous tumor and is most often found in premenopausal women. Having Fibroadenoma does not increase your risk of breast cancer. This tumor is usually round or oval with a rubbery texture. 




These are benign fat tissue growths that are normally completely harmless. They can form anywhere along the body including the scalp. Unlike swollen lymph nodes, lipomas are not painful to the touch. 


Cancer in the Lymph Nodes

source: Canva


Your lymph nodes do many important jobs in the body, including breaking down cancer cells. Unfortunately sometimes cancer can affect the lymph nodes. This occurs in one of two ways: the cancer may form initially in the lymph nodes or it may form elsewhere and then spread to the lymph nodes. 


If a cancerous tumor starts in the lymph nodes it is called lymphoma. This is less common than cancer starting elsewhere in the body and then spreading to the lymph nodes. When cancer initially forms elsewhere in the body, cells can break off from the tumor and travel through the lymph fluid. If they are not destroyed by the lymph nodes, they can form a new tumor. 



Source: Canva


In order to diagnose swollen lymph nodes your doctor will perform a physical exam and ask about any pain in the area as well as any noticeable changes to the lump. 


The doctor will examine the area by using their hand to check for the size and texture of the lump. This process is called palpitation. 


If the doctor concludes that the lump is benign, they may order no further action to be taken. If the doctor needs more information to make their diagnosis they may order some testing. These tests are to rule out infection, allergic reaction and any cancerous changes. These tests include:


  • breast X-ray (mammogram), which is an imaging test that may allow your doctor to see the lump better
  • complete blood count to measure the number of platelets, red blood cells, and white blood cells in your system
  • MRI or CT scan imaging
  • biopsy, which involves removing a small piece of tissue or the entire lump for testing
  • allergy testing
  • a culture of fluid from the lump to look for infection



Source: Canva


The reason for the swelling will determine the best course of treatment. If the swelling was due to a bacterial infection, it should subside after a round of antibiotics is taken. If the infection was viral there is no treatment, although over the counter pain reliever may be recommended to help with the inflammation. 


When the swelling is the result of an allergic reaction it should subside once the allergen is avoided or proper medication is administered. 


If the lump is the result of a cancer diagnosis, it will only subside after treatment of the cancer is completed. This treatment can include: 


  • Chemotherapy
  • Radiation
  • Surgery

Don’t Wait to Feel Better

a group of doctors with a female doctor in front

Source: Canva


No matter what is causing the lump or bump in your armpit, the best chance of recovery is early intervention. Don’t wait to schedule an appointment with your doctor. Connect with a real North American doctor 24/7 with Your Doctors Online. We make it easy to access the medical advice of a physician from the comforts of home. Connect with us today. 


*Not her real name

Disclaimer: This article provides general information and is not intended to diagnose, treat or cure any disease or medical condition. If you require specific advice, please consult one of our medical professionals through the app. However, in case of an emergency, please call 911.

About Richard Honaker M.D.

Dr. Richard Honaker has over 40 years of experience as a primary care physician specializing in several different areas of medicine. He is able to provide expert case review and analysis for insurance and workers compensation cases as well as providing online medical consultations as the Chief Medical Advisor for Your Doctors Online.

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