Read below about armpit lump, including causes, treatment options and remedies. Or get a personalized analysis of your armpit lump from our A.I. health assistant. At Buoy, we build tools that help you know what’s wrong right now and how to get the right care.

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Armpit Lump Symptoms

A "lump" is a general term, meaning any kind of swelling, enlargement, or bump. Lumps in the armpit can have a wide range of causes. Most are not serious and can be easily treated. [1]

However, a newly discovered unexplained lump under your arm should be examined by your medical provider, especially if you are a woman. These lumps can be symptoms of a more serious illness and, proper treatment – if needed – can begin right away. [5]

Most of the time, these armpit lumps are swollen lymph glands. The lymphatic system, made up of many small glands and a circulatory system of its own, runs throughout the body and is responsible for filtering out any infectious agents. That's why lymph glands, or nodes, are very important but also vulnerable to infections and tumors of their own. An armpit lump is also called an axillary lump, from the Latin word for armpit. [1,3]

Characteristics: ### [3,6]

  • A lump or swelling anywhere in your armpit, just below your skin. The lump may be:

    • Large or very small.
    • Soft, rubbery, or firm.
    • Painful, tender, or painless.
    • Reddened, or with normal skin color.
    • Hot to the touch, or normal.
    • Barely visible under the skin, or an obvious lump that hangs down.
  • Fever is sometimes present.

Duration:

  • If the armpit lump is actually swollen lymph nodes due to an infection, the swelling usually goes away soon after the infection is cleared up. [6]

Are armpit lumps serious? ### [6]

  • A small lump or swelling that clears up on its own is probably not serious.
  • A lump that is reddened, painful, and/or persistent should be examined by a medical provider.
  • A lump that is large, reddened, and painful and continues to grow – especially if you also have fever – should be examined by a medical provider.

Armpit Lump Causes Overview

Many conditions can have an armpit lump as a symptom. The most common are those involving the lymph nodes under the arm, as well as infections and, more rarely, tumors. [1]

The most common armpit lump causes:

  • Having enlarged lymph nodes, which can feel like lumps under the skin of the armpit, is a sign that the body is fighting some sort of disease. It is usually a systemic disease affecting the entire body and can be either a bacterial or a viral illness. [1]
  • A bacterial infection of the lymph node itself also causes swelling, but it will usually be painful and reddened as well. [2]

Less common armpit lump causes:

  • A lump of bacterial infection, called an abscess or boil, can form just under the skin of your armpit, arm, or breast. It is often caused by shaving. Even a small break in your skin can allow bacteria, most often staphylococcus or streptococcus, to get in and begin to grow. [2]
  • A cyst, which is a small, isolated sac of fluid, pus, air, or other substance, can form almost anywhere in the body. Cysts are usually the result of some trauma or irritation such as shaving, having an ingrown hair, and/or using an antiperspirant (antiperspirants block the pores.) [2]
  • An insect bite, especially a mosquito bite, can form a small red bump under your arm. These bites are usually very itchy where most other kinds of armpit lumps are not. [3]

Infrequent armpit lump causes:

  • Some vaccinations can cause swollen lymph nodes in your armpit and elsewhere, because the vaccine actually gives you a mild case of the disease in order to stimulate your own immune system. [1]
  • In women who are nursing an infant, a milk duct can sometimes become blocked. This causes lumps to form throughout the breast and well into the armpit, since the breast tissue does extend beneath the arm. [4]
  • A lump under your arm can be linked to breast cancer or to cancer of the lymph nodes. This is most important reason to have any unusual lump checked by your medical provider. [5]

A.I. Health Assistant Causes for Armpit Lump

The list below shows results from the use of our A.I. Health Assistant by Buoy users who experienced armpit lump. This list does not constitute medical advice.

  1. 1.Skin Cyst

    An epidermoid cyst is a closed sac under the skin filled with a cheese-like or oily material. It is caused by trauma or surgery.

    Resolves with treatment

    Rarity:
    Common
    Top Symptoms:
    skin-colored armpit bump, marble sized armpit lump, small armpit lump
    Symptoms that always occur with skin cyst:
    skin-colored armpit bump
    Urgency:
    Wait and watch
  2. 2.Skin Abscess

    A skin abscess is an infection of the deeper skin that's typically due to bacteria seen on the skin. Recently, infections are more frequently caused by Staph. Aureus (puts the "staph" in "staph infections"), which is dangerous and requires treatment.

    Good prognosis with treatment

    Rarity:
    Common
    Top Symptoms:
    rash with bumps or blisters, red rash, red skin bump larger than 1/2 cm in diameter, pus-filled rash, rash
    Symptoms that always occur with skin abscess:
    rash with bumps or blisters
    Urgency:
    Primary care doctor
  3. 3.Lipoma

    A lipoma is a noncancerous growth of fatty tissue cells. A lipoma can develop in almost any organ of the body although they are most commonly found in the subcutaneous layer just below the skin.

    Resolves with treatment

    Rarity:
    Uncommon
    Top Symptoms:
    skin-colored groin bump, marble sized groin lump, small groin lump
    Symptoms that always occur with lipoma:
    skin-colored groin bump
    Urgency:
    Wait and watch
  4. 4.Boil (Furuncle)

    Boils are infections of a hair follicle that creates a small pocket of inflammation full of pus. It's typically caused by a common bacteria called S. Aureus.

    5-10 days

    Rarity:
    Uncommon
    Top Symptoms:
    pink or red facial bump, small facial lump, painful facial bump, marble sized facial lump, constant skin changes
    Symptoms that always occur with boil (furuncle):
    pink or red facial bump
    Symptoms that never occur with boil (furuncle):
    fever
    Urgency:
    Self-treatment
  5. 5.Enlarged Lymph Nodes in the Armpit

    Enlarged lymph nodes occur when the node becomes larger as it fills with inflammatory cells. This often is a result of an infection but can occur without a known cause.

    Enlarged lymph nodes should go away within a week or two.

    Rarity:
    Common
    Top Symptoms:
    armpit lump, movable armpit lump
    Symptoms that always occur with enlarged lymph nodes in the armpit:
    armpit lump
    Symptoms that never occur with enlarged lymph nodes in the armpit:
    fever, unintentional weight loss, hard lump in the armpit
    Urgency:
    Phone call or in-person visit

    Armpit Lump Checker

    Take a quiz to find out why you’re having armpit lump.

    Armpit Lump Quiz
  6. 6.Pimple

    Acne, also known as pimples, occurs when hair follicles become clogged with oil & dead skin cells. Acne is extremely common and ranges from mild to severe.

    The severity of the acne dictates treatment-type and duration. With proper treatment, acne should resolve in weeks to months. In some cases, acne is a long-term condition.

    Rarity:
    Common
    Top Symptoms:
    pink or red facial bump, small facial lump, painful facial bump, marble sized facial lump
    Symptoms that always occur with pimple:
    pink or red facial bump
    Urgency:
    Self-treatment
  7. 7.Folliculitis

    Folliculitis is a common skin problem where hair follicles are infected by bacteria or fungi.

    Mild cases clear in a few days. More severe ones can cause hair loss and scarring.

    Rarity:
    Common
    Top Symptoms:
    small facial lump, pink or red facial bump, face itch, facial bump leaking yellow/milky fluid, yellow or white facial bump
    Symptoms that always occur with folliculitis:
    small facial lump
    Urgency:
    Self-treatment
  8. 8.Hodgkin's Lymphoma

    Hodgkin lymphoma is a cancer of the lymphatic system, which is part of the immune system. Cells in the lymph nodes grow abnormally and may spread beyond the lymphatic system.

    Curable but survival rates are variable

    Rarity:
    Rare
    Top Symptoms:
    fatigue, loss of appetite, abdominal pain (stomach ache), shortness of breath, fever
    Symptoms that never occur with hodgkin's lymphoma:
    pulsing armpit mass, armpit lump that comes and goes, shrinking armpit lump, pink or red armpit bump, black or brown armpit bump, yellow or white armpit bump, bleeding armpit bump, armpit bump leaking yellow or milky fluid, armpit bump leaking clear fluid, scabbed armpit bump, scaly armpit bump, neck lump that comes and goes, shrinking neck bump, pink or red neck bump, black or brown neck bump, yellow or white neck bump, bleeding bump, bump leaking clear fluid, neck bump leaking yellow/milky fluid, scabbed bump, scaly neck bump, pulsing chest mass, chest lump that comes and goes, shrinking chest bump, pink or red chest bump, black or brown mass on chest, yellow or white chest bump, blue bump on the chest, bleeding chest bump, chest bump leaking clear fluid, chest bump leaking yellow/milky fluid, scabbed chest bump, scaly chest bump, pulsing groin mass, groin lump that comes and goes, shrinking groin lump, pink or red groin bump, black or brown groin bump, yellow or white groin bump, inflamed groin bump, scaly groin bump, bleeding groin bump, groin bump producing clear fluid, groin bump producing yellow or milky fluid
    Urgency:
    Primary care doctor
  9. 9.Wart

    Warts are non-serious skin growths caused by a virus that infects the top layer of the skin. They are contagious. Thus, warts on the face are often spread there by the hands, and vice versa.

    78% go away in 2 years

    Rarity:
    Common
    Top Symptoms:
    small facial lump, painless facial bump, skin-colored facial bump, scaly facial bump
    Symptoms that never occur with wart:
    headache
    Urgency:
    Self-treatment
  10. 10.Breast Cancer

    Breast cancer affects one in eight women during their lives. It is caused by uncontrolled and fast growth of damaged cells in the breast tissue. These cells can also move to the lymph nodes and sometimes other organs. The main symptom of breast cancer is a hard or firm, non-mobile, usually non-tender lump in the breast that increases in size.

    Indefinite

    Rarity:
    Uncommon
    Top Symptoms:
    breast pain, armpit lump, breast mass or retraction, breast lump, nipple discharge
    Urgency:
    Primary care doctor

Armpit Lump Treatments and Relief

Seek immediate treatment in the emergency room if you have a lump in your armpit that is reddened and painful, and you also have fever and/or difficulty breathing or swallowing. [7]

Schedule an appointment for:

  • An unexplained lump in your armpit, especially if you are a woman and have no other symptoms of illness. [5]
  • Swelling that persists, or worsens, over several days, especially if you also develop a fever or other symptoms of illness. [7]

Armpit lump remedies that you can try at home:

  • Drinking plenty of fluids, especially if you have fever. [7]
  • Taking over-the-counter pain relievers and nonsteroidal anti-inflammatory drugs such as ibuprofen. [7]

FAQs About Armpit Lump

Here are some frequently asked questions about armpit lump.

Why is the lump on my armpit painful?

Lumps in the armpit, even painful lumps, are common occurrences and the vast majority of encounters are non-life or limb threatening. Usually a painful lump in the armpit is the product of a clogged pore, a swollen lymph node, or a cyst. These bumps can be nearly pea-sized and inflamed and tender to the touch. They can cause pain upon lifting the arm as well. [6,8]

Will my armpit lump go away on its own?

Yes, most armpit lumps will dissipate with time given that their cause also resolves. Bumps and lumps from infection or blockage of pores will disappear as infection or bodily illness resolves. In the case of a skin infection, this may take a week or so. In the case of a swollen lymph node from a viral infection, it may take up to 10 days. If the lump is from using a deodorant or lotion that blocks pores (e.g. one containing aluminum), resolution may require switching products. Persistent armpit lumps, especially if hard and fixed in place, deserve medical attention. [5,7,9]

Why do I get lumps only under one arm?

Lumps under one arm are often due to blockage of pores on one arm. This can be due to overuse of one arm, causing more sweating and a backup of sweat and bacteria. it can be due to application of deodorant or lotion more heavily on one arm than the other. It can be due to an infection in the upper or forearm of the corresponding armpit as the lymph nodes respond to increased white blood cells, or it can rarely be due to a local malignancy or cancer. If it does not resolve, you may require medical evaluation. [5,9]

Can shaving cause armpit lumps?

Yes. Shaving can cause armpit lumps. This is most commonly caused by ingrown hairs after shaving. Shaving may create small cuts and abrasions in the skin of the arm pit. As they heal and skin regrows, the hair may grow into the skin instead of outward. Hair follicles are often colonized by bacteria. If the hair grows into the skin, the bacteria will have no means of drainage from the skin and a bacterial infection may form causing inflammation and pain. [10]

Can I pop the lump on my armpit?

Yes, if it is a superficial and small local infection or pimple it can be popped, but it is best not to pop any pustules or pimples in the armpit without medical evaluation as it is an uncommon place to acquire pimples. It may even spread the bacteria causing more pimples or further inflammation of the tissue causing additional damage and tenderness. [9]

Questions Your Doctor May Ask About Armpit Lump

  • Q.What color is the bump?
  • Q.Any fever today or during the last week?
  • Q.Do you have a rash?
  • Q.Do you feel pain when you touch the bump?

If you've answered yes to one or more of these questions, try our armpit lump symptom checker to find out more.

Armpit Lump Quiz

Armpit Lump Symptom Checker Statistics

  • People who have experienced armpit lump have also experienced:

    • 21% Armpit Pain
    • 8% Pain in One Armpit
    • 6% Painful Armpit Lump
  • People who have experienced armpit lump had symptoms persist for:

    • 43% Less Than a Week
    • 21% Over a Month
    • 13% Less Than a Day
  • People who have experienced armpit lump were most often matched with:

    • 100% Skin Abscess
  • Source: Aggregated and anonymized results from visits to the Buoy AI health assistant (check it out by clicking on “Take Quiz”).

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Armpit Lump Quiz

References

  1. Mount Sinai. Armpit lump. Mountsinai.org.Mount Sinai Link. Published 2018. Accessed September 28, 2018.
  2. Mostellar Medical Center. Armpit lump. Mostellarmedical.org. Mostellar Link. Accessed September 28, 2018.
  3. Healthwise staff. Swollen Glands, Hernias, and Other Lumps Under the Skin. uofmhealth.org Michigan Medicine Link. Published November 20, 2017. Accessed September 28, 2018.
  4. Farrokh D, Alamdaran A, Yousefi F, Abbasi B. Galactocele in the Axillary Accessory Breast Mimicking Suspicious Solid Mass on Ultrasound. Case Reports in Obstetrics and Gynecology. 2017;2017:4807013. Case Rep Obstet Gynecol Link. Published April 9, 2017. Accessed September 28, 2018.
  5. Radiology Info. Breast Cancer. RadiologyInfo.org. Radiology Info Link. Reviewed September 5, 2018. Accessed September 28, 2018.
  6. NHS Direct Wales. Lumps and swelling. nhsdirect.wales.nhs.uk. NHS Link. Updated May 5, 2015. Accessed September 28, 2018.
  7. Page not found (https://safety.fsu.edu/guardian00sep.pdf)
  8. PubMed Health. Acne Lesions. ncbi.nlm.nih.gov. NCBI Link. Accessed September 28, 2018.
  9. Breastcancer.org. Armpit Discomfort. breastcancer.org. Breast Cancer Link. Updated February 18, 2017. Accessed September 28, 2018.
  10. NHS. Ingrown hairs. nhs.uk. NHS Link. Updated May 24, 2016. Acccessed September 28, 2018.