Underarm Cysts – Causes, Diagnosis & Treatment

Finding unexpected and ugly lumps anywhere on the body for both males or females can be an intimidating and potentially chilling development. If those lumps are underarm/armpit cysts, the problem is likely more annoying than frightening.

An underarm cyst is primarily a sac under the skin containing pus similar to pimple. They usually result from a hair follicle or an oil-secreting gland within the hair follicle becoming damaged. Shaving is the major cause of the development of underarm cysts.

Underarm Cyst

Additionally, any kind of damage to the skin, like excessive exposure to ultraviolet rays or a wound, can generate conditions that may result in a cyst.

Most armpit cysts are painless, harmless and can be left untreated. However, if a cyst appears and it bothers you for cosmetic reasons or worse, it becomes infected, you must see a physician.

Once a cyst begins to grow, it fills with a protein known as keratin, which has foul odor and yellowish color. The sac grows to become a small protrusion on the skin at the area of initial injury. When it comes to diagnosing armpit cysts, you must know that all lumps are not cysts. It could simply be a swollen or distressed lymph node (glands which aid your body in fighting infection). Albeit the only sure method to diagnose a lump that has popped up under the arms is to have a doctor examine it, since there are basic symptoms to scout for. Cysts are typically skin-colored, and unless infected, they are painless.

They are small growths and usually do not grow much larger than two inches or five centimeters across.

Moreover, you can check the growth by squeezing the lump between the forefinger and thumb, and moving it back and forth. If it wiggles, it is likely a cyst. Another good indicator to know that the growth is benign is whether you have recently injured the skin near the lump/cyst. Acne, deodorants and shaving can all cause skin damage and irritation leading to a cyst.

Read on to know the causes, diagnosis and treatments for underarm cysts

Causes of Armpit Cysts

Shaving and Antiperspirants

Cysts found in the underarm area can be caused by chemicals present in antiperspirants or by shaving. The cysts are usually observed in adolescents, who have just begun to shave the underarms. Shaving the direction of hair-growth (or T-shape) and using herbal shaving gels plus antiperspirants can help alleviate occurrence of razor bumps.

Lipoma (or Fatty Growths)

Benign harmless armpit cysts called lipomas can also look like armpit cysts. Lipomas are small, soft-to-the-touch lumps that develop under the skin. If the lump grows in size or turns painful you should consult with your doctor.

Hidradenitis Suppurativa

This condition develops on skin areas that have numerous oil and sweat glands. It is essentially observed around the hair follicles. The areas prone to this condition are the groin, anus and armpits. Dark, benign lumps develop which can be hard or leak and can often lead to scarring.


Underarm cysts can occur due to cancer such as Hodgkin’s lymphoma (cancer of lymph tissue) or leukemia, or Non-Hodgkin’s lymphoma (cancer of lymphoid tissue).

Viral and Fungal infections

Fungal infections are another reason one can be having armpit lumps. Viral infections such as shingles, chicken pox and HIV are other conditions that can lead to the development of armpit cysts.


Vaccinations utilized for allergic reactions, typhoid, measles, mumps or smallpox can cause lumps within the armpits.

Armpit Cysts Diagnosis

Any lump that develops on the body unexpectedly is an unwanted intruder. Additionally, not knowing what needs to be done if one pops up under the arms can be annoying mentally and physically. The only sure-fire method to diagnose a lump under the arms is to consult a doctor and have it tested. Physicians know the symptoms to look for and exactly whether the lump in question is a ‘cyst’ or not.

At-Home Diagnosis

Wiggle Test

You can check the growth via squeezing the lump between the forefinger and thumb, and move it back and forth. If it wiggles, it is likely a cyst, as they tend to be easily movable.

What to expect at your visit to the doctor’s office:

Your doctor will perform a thorough physical examination and ask a few questions about your medical history and symptoms. Some questions you may be asked are:

  • When did you first notice the lump?
  • Are you breastfeeding?
  • Is the lump painful?
  • Is it becoming better, worsening or saying the same?
  • Have you noticed any factors that make it worse?
  • What other symptoms are present?

The physical examination performed by the doctor may include palpation – gently pressing the nodes with the fingertips. Testing often depends on what is found during the physical examination. The tests that may be done are:

  • Liver function tests
  • Kidney function tests
  • Blood tests, like complete blood count (CBC)
  • Platelet count
  • Mammogram
  • Chest X-ray
  • Lymph node biopsy

Treatment Options

Medical Treatments

  • If the cyst is large and contains pus, the doctor may drain the pus by using a needle
  • If the cyst grows too large, causes discomfort , pain and obstructs your daily activities, then your doctor will remove it surgically. If your doctor suspects that the cyst is cancerous, he will do a biopsy and remove it surgically
  • Laser treatment is another technique utilized for treating cysts. If the cyst is on a sensitive area, laser is utilized to vaporize the lump. This technique helps to reduce scarring
  • If the cyst is inflamed, the doctor may inject the lump using a corticosteroid to lessen the swelling

Home Treatments

  • Make sure you do not squeeze, open or drain the lump, as this can lead to an infection
  • If it is a sebaceous cyst, take a towel and soak it in hot water. Wring the excess water from the towel and put it on the affected area. This will help to drain and clean it. If you have an infected cyst, do not use this method
  • For skin care, keep the underarm areas clean by washing the skin containing the lump and its surrounding area properly using an antibacterial liquid
  • If you have a ruptured cyst, there is a chance that you may have an underlying serious infection. For a ruptured cyst, wash the area with antibacterial soap and water. Apply an antibacterial lotion with a cotton ball and cover the area with a band-aid made of a gauze pad. This will help in keeping the dirt away from the affected area until you visit the doctor


A lump in the underarm area triggered by a viral infection will eventually go away without treatment. On the other hand, an underarm lump caused by an allergic reaction will go away once the ‘trigger’ is eliminated. No treatment is necessary for an underarm cyst caused by normal breast tissue.

A lump in the underarm region caused by a lipoma is totally harmless, unless it becomes so large that it causes distress. The outlook for cancerous lumps depends on the particular kind of cancer, such as:

  • Leukemia
  • Hodgkin’s lymphoma
  • Breast cancer
  • Non-Hodgkin’s lymphoma

The underlying reason behind underarm cyst can be as simple as shaving or it can be as serious as cancer or AIDS. Therefore, it is vital that you see a physician if the lump or cyst does not go away on its own within two weeks.

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