Last reviewed by Dr. Raj MD on January 12th, 2022.
An underarm cyst is a lump under your skin and can be caused for many different reasons. Men appear to be at a higher risk of developing cysts than women are and can even appear in children.
What is a cyst?
In general any cyst, whether it is an underarm cyst or on another part of your body, is a closed pouch, or pocket, of tissue. Once it begins to grow it will start to fill with a protein called keratin, which is yellowish in color and has a foul odor. Most underarm cysts are small and do grow larger than two inches across but they can be larger. When they are small, they can resemble a pimple.
Symptoms of Underarm cyst
Some of the general symptoms that you may experience with an underarm cyst can include:
- Sudden loss of appetite
- Symptoms that are flu-like
If Hidradenitis suppurativa is the cause of an underarm cyst you will notice tender dark bumps that can be leaking or hard, and can lead to scarring.
Pictures of Underarm cyst
Picture of Underarm cyst (Armpit lump)
Small Armpit cyst looking like a boil
Underarm cyst that is painful
Causes of Underarm cyst
Some of the many reasons to develop an underarm cyst include clogged sebaceous glands, which are endocrine glands in your skin that secrete a waxy or oily matter that helps to waterproof and lubricate your skin, along with these reasons.
- Shaving, usually in adolescents who are just starting to shave under their arms
- The chemicals that are present in antiperspirants
- Bacterial infections — this can be due to skin disorders that are bacterial infection-related. It can also be due to cat scratch disease or the inflammation of a lymph vessel known as ascending lymphangitis. It could also be caused by an inflammation of your lymph nodes known as lymphadenitis. Using a dirty razor to shave can also cause a bacterial infection.
- Hidradenitis suppurativa — this medical condition occurs in the areas where there are many oil and sweat glands such in your armpit. It is normally observed around your hair follicles.
- Lipoma — these are harmless non-cancerous underarm cysts that are just fatty growths that are usually small and soft-to-touch.
- Fungal infections
- Viral infections — these can include AIDS, shingles, and chickenpox and the common cold
- Cancer — underarm cysts can also be caused by cancers such as Hodgkin’s lymphoma, which is cancer of your lymph tissue, leukemia, or
- Non-Hodgkin’s lymphoma, which is cancer of your lymphoid tissue
- Autoimmune diseases such as juvenile rheumatoid arthritis, systemic lupus erythematosus, and rheumatoid arthritis
- Chronic fatigue syndrome
- Trauma to your underarm
- Allergic reaction to a new antiperspirant or shaving gel or cream
- Breast cancer — this underarm cyst will grow slowly and are very hard and small.
Treatment for Underarm cyst
You should see your physician if it has not gone away after fourteen days or it has gotten larger and is causing you discomfort. If it is a small cyst it will usually not need any treatment because they will go away on their own but it is large and causes you discomfort you should see your physician. One important thing that you want to make sure that you do not do is to drain, open, or squeeze the underarm cyst as it can lead to skin infection.
- If it does require treatment your physician may drain the cyst using a needle.
- It can also be removed by surgery, especially if your physician thinks it could be cancerous and a biopsy is needed to make that decision.
- If your underarm cyst is inflamed your physician may inject it with a corticosteroid to help reduce any swelling
- Laser treatment to vaporize the cyst and to help reduce any scarring
- For an infection your physician may prescribe antibiotics. If the infection is not treated it can cause your underarm cyst
- Shaving — use an herbal shaving gel and make sure that you are shaving in the direction that the hair is growing can help to reduce razor bumps and underarm cysts. Use a new razor if the razor is dirty or is not shaving the area well.
- Keep your underarm area clean by washing the cyst and surrounding skin gently with an antibacterial soap.
- If the underarm cyst is a sebaceous cyst and it is not infected, you can take a washcloth and dip it in warm water, making sure to wring out the excess water. Hold it on your underarm to help drain the cyst and clear it.
- If your underarm cyst ruptures you could develop a severe infection so make sure that you wash it gently with warm water and antibacterial soap. Using a cotton ball apply an antibacterial cream and cover with a bandage using a gauze pad to keep the dirt away until you can see your physician.
- If it is due to an allergic reaction to a new antiperspirant or shaving gel or cream, switch back to your old one.