What's with the lumps in my underarm area?

Dear Alice,

I have two lumps in my underarm and they are very sore, they go away after a week or two, and then come back in a couple of weeks. It's been happening for almost two years. Some of my family says it could be a reaction from my deodorant. What is this caused from, what could this be? Is it possible that it is cancerous? It happens under both arms. Sometimes it gets so big that it hurts to even have my arms down to my side.

Dear Reader,

Generally speaking, the lumps you describe could be due to any number of causes, including cysts (fluid-filled sacs) and enlarged lymph nodes. You mention a cycle of these lumps appearing and then disappearing. If you’re assigned female at birth, it might be good to note whether they correlate with certain points during the menstrual cycle. Breast tissue continues underneath the arm, and extra fluid may accumulate between periods, causing you to feel lumps. As for your concern about these lumps being cancerous — cancer tends to be asymmetrical, meaning that it’s not often found in the same place on both sides of the body. Most cancerous masses stay in one place and don’t spontaneously recede. Ultimately, the best way to determine what exactly is going on is to consult with a health care provider. Based on what’s causing this soreness they’ll be able to direct you to the appropriate treatment and may be able to recommend some home remedies to alleviate pain.

There could be a number of causes for the lumps in your underarm. It's possible that your lymph nodes are swollen. Lymph nodes protect the body from bacteria, viruses, and cancer cells. As a line of defense, they can swell when they're fighting against cells the body finds undesirable. Under your arm, they may swell due to an infection in your arm or breast, due to infections across the body, or due to cancer. The lumps could also be cysts. It's possible that these lumps are caused by your antiperspirant. These cysts could also be caused by conditions such as cat scratch disease, the certain medicines, or simply be a fatty growth.

Before your medical appointment, you can make some preparations and note your experiences. If possible, try to make the appointment at a time when you expect the lumps to be in full force. They will likely do a physical exam and ask some details about it, such as the first time you noticed it, if it hurts, what makes it worse, if you’re breastfeeding, and if you’re experiencing any other symptoms. You may find it helpful to note any details you have about your experience before your appointment. The appropriate treatment (if needed) will depend on the cause of the lump. For example, if the lump is caused by swollen lymph nodes due to a bacterial infection, antibiotics may be prescribed. If the lumps are caused from an immune disorder or other condition, the underlying cause of the lumps may be treated. Given the wide range of causes, the treatment for the lumps is also wide reaching.

Though it may be tempting, it’s recommended that you don't try to squeeze, poke, or pop the lumps yourself, as it could result in a serious infection. Since you’re experiencing significant pain, your best course of action at this point is to see a medical provider. Hopefully they can quickly diagnose the lumps and make them disappear for good!

Last updated Jun 15, 2018
Originally published Jan 30, 2004

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