Armpit lumps happen in men and women for various reasons, including infections, skin irritations and chronic diseases. They may be as small as a pea or as large as a golf ball. Armpit lumps typically go away on their own. On rare occasions, they’re a sign of cancer.
With an armpit lump, it feels as if there’s a pea or other growth under your skin in the upper-most area of your inner arm. Lumps can develop in men and women of all ages. There can be many reasons for an armpit lump, and most of them aren’t serious.
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In rare cases, an armpit lump can be a sign of cancer. More often, they’re due to irritation, blockages or injuries affecting:
An armpit lump may feel hard, soft or unusually warm.
You may have a fever, along with pain and redness in the area. The lump may also:
Additional causes may include:
Lymph nodes are located throughout your body, including your armpits. They contain white blood cells that help your immune system fight infections. When your body detects bacteria and viruses, they get trapped in your lymph nodes, causing temporary swelling.
A small number of people get an armpit lump after receiving a vaccine. This may include the COVID-19 vaccine or flu shot. The armpit lump often appears on the side of your body where you received the shot.
These armpit lumps occur because the vaccine triggers an immune system response that produces antibodies. This type of lump is a sign that the vaccine is helping you build immunity. It typically goes away in a few weeks.
These lumps tend to be painful, nonmobile and hard to the touch. But finding one doesn’t always mean you have cancer. A complete evaluation, including imaging tests and a potential biopsy, is typically necessary to make a diagnosis.
Watchful waiting, meaning monitoring instead of treatment, may be the right option for lumps that are likely to go away on their own.
If you need treatment, care may include:
Most armpit lumps go away on their own, but it can take a few weeks. It’s possible to develop a new armpit lump if you get another infection, receive a vaccine or experience a skin issue. But most lumps are harmless.
You should contact your healthcare provider if the armpit lump:
A note from Cleveland Clinic
It can be concerning to find a lump in your armpit. But most are harmless and go away on their own. Armpit lumps are often a sign of infection that may require antibiotics. Some lumps are due to skin issues and need to be removed. Rarely, an armpit lump can be a sign of cancer. If you’re worried about a lump, the best thing to do is contact your healthcare provider. They can determine what’s causing it and provide treatment if necessary.
Last reviewed by a Cleveland Clinic medical professional on 04/18/2022.
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