Cyst in Armpit: Causes, Treatments And When to See a Doctor

Cyst in Armpit - Causes, Treatments And When To See a Doctor

Discovering a cyst in your armpit or any other kind of armpit lump can make you feel worried and concerned. Because cysts that grow in the armpits are generally painless, you might not even realize you have one. Cysts in your armpits may be as small as a pea or they could develop into a larger cyst or boil that becomes infected and causes pain in your underarm.

There are many reasons why sore lumps can develop in your left or right armpit (medically called axilla). For example, you could suffer from ingrown hairs that infect hair follicles or follicles can become blocked and swollen. Because you have lymph nodes in your underarm which help fight off infection, any infection in your body can cause lymph nodes to become swollen and maybe painful.

Because any new lump could be a sign of something more serious, you should always have a new lump that doesn’t go away checked out by a doctor to make sure it’s benign.

In this article you will find out what causes cysts in your armpit, how to differentiate between a benign cyst and a worrisome lump, home remedies for treating armpit cyst and when to see your doctor.

What are Cysts in Armpits?

Cysts in the armpits are usually harmless sac-like structures that are filled with pus, liquid, or other material. For example, if a cyst becomes filled with sebum (the oil the skin produces) or keratin, the sac may fill with a soft, cheese-like substance. They can appear on the left or right armpit or on both sides.

According to Dr. Charles Davis on MedicineNet, cysts feel like lumps or bumps and can sometimes be painful. If the armpit cyst is filled with pus, it is usually called an abscess.1

Dr. William Blahd on WebMD says that cysts are noncancerous and will feel like a small pea under the skin. Usually, it’s possible to move them or roll them under the skin. In this way, it’s usually possible to tell the difference between a benign cyst and a lump that is a cause for worry. If you discover a growth under the skin that is hard and doesn’t move, you should always see your doctor for a checkup.

Symptoms of Armpit Cysts

There are some tell-tale symptoms of cysts that can develop and grow in your armpit or another area of your body.

Very often, cysts are painless lumps or bumps. Dr. Melissa Conrad Stöppler on eMedicineHealth says that cysts usually appear just under the surface of the skin and they can feel hard or soft and they may grow in size.3 However, Dr. Blahd says that cysts that become infected or inflamed will become painful and may need draining or removal by a specialist.2

In general, Dr. Stöppler says that most cysts are the result of small blockages in the flow of body fluids.4

Causes of Cysts in Armpits

Let’s look at some of the causes of cysts in your armpits and why the small sac-like structures can develop in your underarm area.

Armpit cysts caused by ingrown hairs

An ingrown hair is a common reason for a hair follicle in your armpit becoming blocked and developing into a cyst. Usually, shaving or waxing your armpits is one of the main reasons for hair growing back in and infecting the skin, which can then sprout an infected bump in your armpit.

Doctors from the National Health Service say that ingrown hairs can sometimes become infected and inflamed. This can result in a pus-filled pimple or lump in the affected area. Also, the dark, moist conditions in your armpits are just right for bacteria to cause skin infections and abscesses.5

A cyst caused by an ingrown hair in your left or right armpit can be quite painful. One of the ways of preventing these infected bumps becoming a nuisance is to always shave in the direction of hair growth. You should also make sure that your underarm hair is moistened to make shaving easier.

There are many ways that you can get rid of an underarm ingrown hair, for example by exfoliating the skin using a natural olive oil and sugar scrub or baking soda and coconut oil scrub. This helps to remove any dead skin cells and prevents cut hairs growing back into the skin.

Use of antiperspirants

A common reason for having an abscess in your armpit is using antiperspirants. In fact, Dr. Linda Vorvick on MedlinePlus said that antiperspirants (not deodorants) are often a cause of cysts or abscesses that form painful lumps in the armpit.6

Whereas deodorant is only used to eliminate or mask the unwanted odor produced by the bacterial breakdown of sweat, its purpose isn’t to stop the problem of excess sweating. However antiperspirants are designed to prevent the root cause of body odor by blocking sweat from reaching the skin, and thus preventing a bacterial breakdown that causes body odor.

Many antiperspirants contain aluminum to control sweat output. According to the Iranian Journal of Pharmaceutical Research, aluminum forms a plug that blocks sweat output.7 Dr. Colin Tidy on says that aluminum antiperspirants can cause skin irritation or inflammation.8

Because of the harmful chemicals present in many deodorants and antiperspirants, many people choose to use natural home remedies to get rid of underarm odor such as making their own natural deodorant to control armpit odor. You can find out how to make your own coconut oil deodorant using baking soda, arrowroot powder, and antibacterial essential oils or this natural lavender deodorant which contains witch hazel extract, aloe vera gel and essential oils.

These homemade deodorants are very effective and won’t irritate your armpit which can result in a painful infected abscess.

Epidermoid armpit cyst

A pea-sized cyst in your armpit could be an epidermoid cyst. This is a harmless lump that forms from keratin – the substance that skin cells are made of.

According to Dr. Louise Newson on, epidermoid cysts can form anywhere on the body. The cyst sac forms from skin cells and becomes filled with a semi-fluid substance. Generally, epidermoid cysts in your armpit are not painful. However, they may become painful if they get infected.9

Sebaceous cyst in armpit

Another type of cyst that can cause discomfort in your underarm area is a sebaceous cyst. This type of cyst can occur in your armpit if a hair follicle or sweat gland becomes blocked.

Doctors from the Cleveland Clinic say that sebaceous cysts fill with an oily or soft cheese-like material that creates a firm lump. Just like with epidermoid cysts, sebaceous cysts in the armpit will become tender, red, and sore if an infection gets into the cyst.10

Underarm bacterial infection

If bacteria get into some of the pores in your underarm area, you could end up having an armpit abscess or boil. Abscesses and boils are sore, red, painful lumps that are often filled with pus. However, some boils don’t come to a head and can be difficult to drain.

Dr. Carol DerSarkissian on WebMD says that our armpits contain a high concentration of hair follicles and sweat glands. If one or more of the axilla glands gets blocked and fills with infected pus, this will result in an abscess. However, an armpit boil will form if any hair follicles get plugged and infected.11

Other growths of skin like skin tags are also very common in the armpit area.

Hidradenitis suppurative

One reason for having cysts in the armpit is a medical condition called hidradenitis suppurative. This painful skin condition causes small boil-like bumps and cysts to appear near sweat glands and hair follicles, especially in the armpits.

According to doctors from the National Health Service, common places for these cysts and lumps to form are the armpits, around the genitals, below the breasts, and on the buttocks. The abscesses and cysts may start off as a pea-size lump that may ooze pus.12 Hidradenitis suppurative is also a reason for having itchy armpits.


Tissue growth under the skin in your armpit can turn into a lump called a lipoma. Lipomas aren’t technically a cyst because they don’t fill with fluid or pus.

Doctors on WebMD says that lipomas are usually small soft bumps under the skin that appear in the armpits, upper body, thighs, and upper arms. It is thought that a minor injury is the cause of these harmless bumps under the skin. They aren’t painful.13

Swollen lymph nodes

Swollen lymph nodes in your armpit are often the result of a viral infection and can feel like a cyst. Your lymph nodes are part of your body’s immune system and they filter out bacteria, viruses, and other waste products.

According to doctors from WebMD, lymph nodes become swollen because of injury, infection, or a tumor near the lymph node. A lump in your armpit because of infected lymph nodes can be the result of an infection in your arm or hand. In rare occasions, the swelling in the armpit lymph nodes is caused by breast cancer or lymphoma.14


As already stated in this article, cysts are noncancerous lumps that develop under the skin. However, there is always the risk that a lump is more than just a cyst.

The American Cancer Society says that lumps appearing around your armpit could be a sign that breast cancer has spread to the lymph nodes. Sometimes, these lumps appear before breast cancer is discovered. However, benign lumps are much more common than cancerous ones. So, it’s important to have any new lump checked out by your doctor.15

Home Remedies for Armpit Cysts

In many cases, armpit cysts can disappear without taking any action, however some might require treatment. One of the best and most recommended ways to get rid of a cyst from your armpit is to place a warm compress on the cyst. The heat from the compress helps to stimulate blood circulation to the affected cyst. The warmth also helps to reduce pain in the inflamed lump.

This is what you should do to remove a cyst from your armpit:

  • Gently wash your affected armpit with soap to remove any bacteria on the skin’s surface.
  • Dip a washcloth in hot water and squeeze out the excess water.
  • Apply the compress to the cyst and hold in on your armpit for 20-30 minutes.
  • Every so often, dip the washcloth in hot water to keep it warm.
  • Repeat the process 3-4 times a day to help bring the cyst to a head and speed up the healing process.
  • When pus starts to drain from the cyst, apply a clean bandage to prevent bacteria getting into the wound.

For more information on how to treat an armpit cyst naturally, please read my article on the best ways to get rid of a sebaceous cyst. There you will find how home remedies like tea tree oil, witch hazel, and aloe vera can help to eradicate the cyst and prevent infection.

Dr. Stephanie Gardner on WebMD warns against trying to get rid of a cyst yourself by squeezing it. If you try to pop a cyst, you could cause the lump to become more inflamed and infected and possibly make the infection spread.16

Can armpit cysts be prevented?

Dr. Melissa Conrad Stöppler says that, in general, cysts can’t be prevented.17

When to See a Doctor for a Cyst in the Armpit

Cysts are generally harmless and don’t need any treatment. However, for esthetic reasons or if the cyst develops an infection, you may want to have a doctor examine the cyst and remove it.

If an armpit cyst is bothering you, Dr. Colin Tidy on recommends visiting your doctor in these circumstances:18

  • The cyst causes embarrassment or discomfort in your armpit.
  • The cyst is sore and tender to touch and there are signs of infection.
  • The lump in your armpit starts to grow rapidly.
  • The armpit lump feels hard or firm or doesn’t go away within 2 weeks.

Read my other related articles:

Article Sources

  1. MedicineNet. Cysts.
  2. WebMD. Cysts, lumps, bumps, and your skin.
  3. eMedicineHealth. Cysts.
  4. eMedicineHealth. Cysts.
  5. NHS. Ingrown hairs.
  6. MedlinePlus. Armpit lump.
  7. Iran J Pharm Res. 2011 Summer; 10(3): 641–645.
  8. PatientInfo. Excessive sweating.
  9. PatientInfo. Epidermoid and pilar
  10. ClevelandClinic. Sebaceous cysts.
  11. WebMD. Picture of the armpit.
  12. NHS. Hidradenitis suppurative.
  13. WebMD. Lipoma.
  14. WebMD. Swollen lymph nodes.
  15. Cancer. Breast cancer symptoms.
  16. WebMD. What’s the treatment for cysts?
  17. eMedicineHealth. Is it possible to prevent cysts?
  18. PatientInfo. Lumps.

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