Swelling in Armpit

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What is swelling in the armpit?

A swelling in the armpit or underarm area usually feels like a discrete lump or bump, rather than diffuse swelling across the entire area. The medical name for the armpit is axilla, so another name for this symptom is axillary swelling. You may or may not have other symptoms along with a swollen armpit.

There are various possible causes for armpit swelling. Some of these causes are more concerning than others. Because a swollen underarm can be potentially serious, it’s important to see your doctor for a diagnosis. Contact your doctor if an unexplained underarm lump doesn’t go away within a couple of weeks or gets bigger. Women should seek prompt medical care for a lump in the armpit. It is a possible sign of breast cancer. You should also seek prompt medical care for a hard lump that is fixed, meaning you can’t move it around within the tissue.

What other symptoms might occur with a swollen armpit?

Some armpit lumps have no other symptoms, are painless, and do not cause any discomfort. However, people often notice additional symptoms along with swelling. These symptoms can include:

These symptoms can occur on one side or both, depending on the cause. It’s important to see your doctor whether you have these other symptoms or not. Your doctor should evaluate even a painless lump or swelling without any other symptoms.

What causes armpit swelling?

There are several possible reasons for your armpit to swell up. One of the most common reasons is a swollen lymph node. You have several lymph nodes in each armpit. Some of them are close to the skin, while others are deeper. They act as filters for the lymph system in your upper body. When your immune system starts fighting an infection, the lymph nodes help trap viruses, bacteria, and other cells. Usually, this means the lymph nodes on both sides of your body will be swollen, including the ones under your arm and in your neck. This is bilateral lymphadenopathy. It is a normal response to an infectious disease or infection.

A swollen lymph node on one side is unilateral axillary lymphadenopathy. Sometimes, this is more cause for concern because it can be a sign of advanced breast cancer. Lymph nodes under the arm are common places for breast cancer to spread. However, there can be other reasons for swollen lymph nodes on just one side including:

Other possible causes of armpit swelling include:

Seeing your doctor is the only way to know for sure what is causing an armpit lump or swelling. In general, the sooner you seek medical care and any necessary treatment, the better the outcome is likely to be.

What are the potential complications of armpit swelling?

The possible complications from armpit swelling depend on the underlying cause. Ignoring the lump or swelling can lead to more problems and possibly more intensive treatments. So don’t delay seeing your doctor. Your doctor will want to know about all your symptoms and will perform a physical exam. You may also need imaging tests or lab tests to help your doctor diagnose the cause. Getting a timely diagnosis offers the best chance of treatment success.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Aug 29
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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  4. Hidradenitis Suppurativa. American Osteopathic College of Dermatology. http://www.aocd.org/?page=HidradenitisSuppura
  5. Swollen Lymph Nodes. Mayo Foundation for Medical Education and Research. https://www.mayoclinic.org/diseases-conditions/swollen-lymph-nodes/symptoms-causes/syc-20353902