At TheHealthBoard, we're committed to delivering accurate, trustworthy information. Our expert-authored content is rigorously fact-checked and sourced from credible authorities. Discover how we uphold the highest standards in providing you with reliable knowledge.

Learn more...

What are the Most Common Causes of Swelling Under the Arm?

Autumn Rivers
Autumn Rivers

A swollen armpit can be caused by a number of conditions, ranging from mild to serious. This is because the lymph nodes located under the arms can swell up due to infection, injury, or serious diseases. In fact, one of the most common causes of swelling under the arm is an infection, as many areas of the body drain into the lymph nodes in this area. Surface injuries or allergies to certain products, such as deodorant, can also result in swelling. While most causes are mild and treatable, cancer, including melanoma, lymphoma, and breast cancer, can also cause swelling in the lymph nodes.

Since the lymphatic system is supposed to remove bacteria from the body, swollen lymph nodes are often a sign that it is trying to fight off an infection. Infections that come from the hands, arms, and breasts are likely to affect the underarm since these areas drain into the lymph nodes located here. Other signs of infection include chills, a fever, and headache as the body attempts to fight it off.

Lymph nodes under the arm are a common source of under arm swelling.
Lymph nodes under the arm are a common source of under arm swelling.

Injuries on the surface of the skin can also result in swelling under the arm, especially if an infection results. Bites, scratches, and cuts may cause the lymph nodes to flare up, particularly when they are located in the underarm area, such as tiny cuts caused by shaving. Additionally, allergies to certain products, such as deodorant, perfume, soap, and shaving cream, may cause swollen lymph nodes, especially when they enter the body through cuts in the skin. Fortunately, the swelling should go down once the injury heals or the product is no longer used. If the swelling does not disappear on its own within days, the individual may need antibiotics.

Bites and tiny cuts from shaving can cause lymph nodes to swell up temporarily.
Bites and tiny cuts from shaving can cause lymph nodes to swell up temporarily.

Though most cases are quite treatable, armpit swelling can also be a symptom of various types of cancer. Since breast tissue includes the skin under the arm, swelling of this area may be a symptom of breast cancer, especially if it is painless and gradual. Lymphoma, which is cancer of the lymphatic system, can also cause the lymph nodes under the arm to swell, as can melanoma, or skin cancer. For this reason, this symptom should not be ignored. If the swelling does not decrease within a few days, an individual should see a medical professional to determine the underlying cause.

Discussion Comments


Very helpful. I will have a mammogram tomorrow! I have a swelling that is painful under my right arm. I didn't realize how important it is to have this looked at. Thank you everyone.


I have lymph nodes under my arm pit. They are painful. This is the second week and they don't seem to want to disappear. What could be the cause?


A few weeks back, I noticed a "pimple" like bump under my armpit and of course, it went away because it was a pimple or the start of an ingrown hair. Well, it is starting to come back and is tender around the area.

Does anyone think this could be the start of breast cancer? Breast cancer or any type of cancer does not run in my family unless self-inflicted such as lung cancer from smoking cigarettes for, at the very least, 50 years.

Please let me know what you women out there think, I am very scared because this bump has come back a second time only a few weeks after it went away. What do all of you think? --Beckie P.


My daughter is 11 and she has a very swollen armpit. It's been this for a few weeks now. We were hoping it would go down. It's not painful, either, so we're going to get her a doctor's appointment right away. I will let you know the outcome.


When I was at my annual exam, the doctor found a small swelling under my arm. I was not even aware that this was there. It was not tender or sensitive, but once she showed me where it was you could definitely feel it.

She scheduled me for a biopsy to see if it was anything I needed to be concerned about. The biopsy ended up negative and they said this was something that would not turn in to any kind of cancer.

It can be pretty scary to realize you have some swelling under your arm because there are so many lymph nodes there. It is something I would want to get checked out right away.


It's a little embarrassing, but if you are going for your physical at the doctor's office make sure you get someone to teach you how to do your own breast exams. It is a good idea to learn how to feel for your underarm lymph nodes because then you will know how to spot if they feel differently, get swollen or develop a lump.

One of the female nurses at my doctor's office taught me how to do a proper breast exam, and while it was a bit awkward I am glad I learned how to do one properly. It is reassuring to know your own body enough to spot if something dangerous develops early on.


There are a lot of people that run into trouble with heavily scented deodorants. When I first started using deodorant I picked the one that I thought smelled the nicest. It was richly perfumed and I liked that a lot. Unfortunately after that my underarms swelled and itched quite a lot.

My doctor told me that I had had an allergic reaction to some of the ingredients and that I should use unscented deodorants from now on. It wasn't a huge deal switching I just wish I had known sooner because the swelling hurt quite a lot. At least the medication my doctor prescribed did its job.


I have a cousin who is allergic to so many products. When she first started shaving, she found out that many types of shaving cream cause her skin to react violently.

She used a peach scented shaving cream under her arms. After she finished shaving, the area started to itch and turn red. Within an hour, it had swollen. It was very sore.

Her doctor told her to put bags of ice under her arm to ease the swelling. He also told her to take a strong antihistamine every four hours until she didn’t need it anymore.

After she recovered, she tried dry shaving, but she always seemed to cut herself this way. She started using a product formulated for sensitive skin, and she didn’t swell.


I am the worst at remembering to replace my disposable razors when the blades become dull. If I shave my underarms with a dull razor, I nick myself and bleed a little, and the cuts become sore for days.

Once I did this before going swimming in a lake. I could not apply deodorant, because it would burn the cuts. So, there was no layer of protection between my tiny open wounds and the lake full of bacteria.

I got an infection, but I did not know it right away. I thought that the swelling under my armpit was due to my cuts. When I got a fever and chills and the swelling increased, I knew it must be something more.

I told my doctor I had gone swimming after shaving, and she said I most likely got the infection there. She gave me antibiotics and told me to stay out of the lake when I have open wounds.


I have never experienced swelling in this area, but I have had swollen glands in my neck. This is probably because the areas of my body that become infected the most are my throat and ears. I seem to get strep throat several times a year, and I swim a lot, so my ears get irritated. The sides of my neck under my jaw swell up and become sore.

I would imagine that swollen lymph nodes under the arms feel much the same. I have a friend who is allergic to several types of deodorant, and hers will swell up for a couple of days if she uses one that bothers her. She says they get sore and tender, and it hurts to fully lower her arms down by her sides.


I agree. I think that when people think about breast cancer they usually don’t consider the lumps under the arm as a possibility for having breast cancer. I heard that it is important to do self exams especially in this area.

They say that you should have your arm raised and with the other hand work in a circular motion in order to detect swollen lymph nodes under the arm. If you do this regularly you will immediately be able to tell if something is not right.

Thank goodness my friend did this because when she got her mammogram results it came up negative, but she found a lump under her arm that turned out to be cancerous.


Very useful article. Thank you.

Post your comments
Forgot password?
    • Lymph nodes under the arm are a common source of under arm swelling.
      By: Alila Medical Media
      Lymph nodes under the arm are a common source of under arm swelling.
    • Bites and tiny cuts from shaving can cause lymph nodes to swell up temporarily.
      By: Kirill Kedrinski
      Bites and tiny cuts from shaving can cause lymph nodes to swell up temporarily.
    • A doctor should be seen if swelling persists as it can also be a cancer symptom.
      By: Alexander Raths
      A doctor should be seen if swelling persists as it can also be a cancer symptom.
    • An allergic reaction to a deodorant may cause swelling.
      By: karam miri
      An allergic reaction to a deodorant may cause swelling.
    • Wearing tight clothing may cause armpit swelling.
      By: Anton Zabielskyi
      Wearing tight clothing may cause armpit swelling.