What Causes Painful Armpit Lumps & When to Seek Care

A painful lump in the armpit is most commonly caused by skin conditions like an armpit cyst or an armpit ingrown hair. A sore lump in the armpit can also be caused by swollen lymph nodes. Read below for more information on associated symptoms, other causes, and treatment options.

Painful Armpit Lump Symptoms

Your armpit is vulnerable to several painful conditions, especially considering the effects of sweat, friction, bacteria, and hygiene. A painful lump in the armpit typically involves either lymph nodes or skin. Lymph nodes are present throughout the body and drain fluid and waste products that build up due to normal physiological functions. They also contribute to the immune response to infections. Certain conditions can cause lymph nodes to become enlarged and painful, and the lymph nodes in one or both armpits can be affected.

Common accompanying symptoms of a painful armpit lump

If you're experiencing a painful armpit lump, it's also likely to experience:

  • Rash
  • Itching or burning sensation
  • Smelly drainage
  • Red streaks
  • Fever: This is a sign of systemic illness.
  • Groin lesions: The same lumps or lesions on your armpit may also appear on your groin.
  • Painful, swollen lymph nodes in multiple parts of the body
  • Bumps appearing similar to acne
  • Scarring

What Causes Lumps Under the Armpits?

Skin conditions

Skin conditions can result in painful armpit lumps, such as the following.

  • Hidradenitis suppurativa: This condition causes chronic inflammation and sometimes infection, resulting in lumps that can drain smelly fluid and lead to scarring over time. The armpits are the area most commonly affected.
  • Ingrown hair: Shaving the armpit can cause ingrown hairs, where the newly cut hairs re-enter the skin instead of growing out. This results in tiny painful bumps in the armpits.

Infectious causes

Infectious causes of painful armpit lumps include the following.

  • Local infection: Since lymph nodes drain waste fluids and respond to infections, they can become enlarged due to a nearby infection. Skin infection in the arm can cause painful swelling of lymph nodes in the armpit. A painful armpit lump could also be caused by an infection in the armpit itself, such as infection of a hair follicle (the structure that surrounds a hair within the skin).
  • Systemic infection: An infection throughout the body may cause swollen and painful lymph nodes in many locations, including the armpits. Other symptoms will likely be present, such as fever and fatigue.

Other causes

Infectious and dermatologic conditions are the most likely reasons for a painful armpit lump, but there are other, less common causes.

  • Pain syndromes: Chronic conditions characterized by widespread pain and fatigue can cause painful swollen lymph nodes throughout the body, including in the armpits. Examples include fibromyalgia and chronic fatigue syndrome.
  • Cancer: Very rarely, a painful lymph node in the armpit could be caused by lymphoma. In this case, there will be an enlarged lymph node that is mostly painless but may become very painful after consumption of alcohol.

This list does not constitute medical advice and may not accurately represent what you have.

Skin cyst

A cyst is a small sac or lump, filled with fluid, air, fat, or other material, that begins to grow somewhere in the body for no apparent reason. A skin cyst is one that forms just beneath the skin.

It's believed that skin cysts form around trapped keratin cells – the cells that form the relatively tough outer layer of the skin.

These cysts are not contagious.

Anyone can get a skin cyst, but they are most common in those who are over age 18, have acne, or have injured the skin.

Symptoms include the appearance of a small, rounded lump under the skin. Cysts are normally painless unless infected, when they will be reddened and sore and contain pus.

Diagnosis is made through physical examination. A small cyst can be left alone, though if it is unsightly or large enough to interfere with movement it can be removed in a simple procedure done in a doctor's office. An infected cyst must be treated so that the infection does not spread.

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

Skin abscess

A skin abscess is a large pocket of pus that has formed just beneath the skin. It is caused by bacteria getting under the skin, usually through a small cut or scratch, and beginning to multiply. The body fights the invasion with white blood cells, which kill some of the infected tissue but form pus within the cavity that remains.

Symptoms include a large, red, swollen, painful lump of pus anywhere on the body beneath the skin. There may be fever, chills, and body aches from the infection.

If not treated, there is the risk of an abscess enlarging, spreading, and causing serious illness.

Diagnosis is made through physical examination.

A small abscess may heal on its own, through the body's immune system. But some will need to be drained or lanced in a medical provider's office so that the pus can be cleaned out. Antibiotics are usually prescribed.

Keeping the skin clean, and using only clean clothes and towels, will help to make sure that the abscess does not recur.

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

Boil (furuncle)

A furuncle, also called a boil, is infection of a hair follicle. The infection forms under the skin at the root of the hair and may occur anywhere on the body.

The infection is caused by bacteria, most often Staphylococcus aureus or "staph." Irritation caused by clothes or anything else rubbing the skin can cause the skin to break down and allow bacteria to enter.

Staph bacteria are found everywhere. Frequent and thorough handwashing, and otherwise maintaining cleanliness, will help to prevent its spread.

Most susceptible are those with a weakened immune system; diabetes; and other skin infections.

Symptoms include a single bump under the skin that is swollen, painful, and red, and contains pus.

It is important to treat the boil, since infection can spread into the bloodstream and travel throughout the body.

Diagnosis is made through physical examination and sometimes fluid sample from the boil.

Treatment may involve incision and drainage of the infection, followed by creams to apply to the site of the boil and/or a course of antibiotic medicine.

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


Lipoma is a word that translates as "fatty tumor," but a lipoma is not cancer. It is simply a growth of fat between the muscle layer and the skin above it.

The exact cause is not known. The condition does run in families and is associated with other unusual syndromes such as adiposis dolorosa, which is similar. Lipomas most often appear after age 40.

Symptoms include a soft, easily moveable lump beneath the skin, about two inches across. A lipoma is painless unless its growth is irritating the nerves around it. They are most often found on the back, neck, and abdomen, and sometimes the arms and upper legs.

It is a good idea to have any new or unusual growth checked by a medical provider, just to make certain it is benign.

Diagnosis is made through physical examination, biopsy, and imaging such as ultrasound or CT scan.

Most of the time, treatment is not necessary unless the lipoma is unsightly or is interfering with other structures. It can be removed through surgery or liposuction.

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

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.

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


Pimples are also called comedones, spots, blemishes, or "zits." Medically, they are small skin eruptions filled with oil, dead skin cells, and bacteria.

Pimples often first start appearing at puberty, when hormones increase the production of oil in the skin and sometimes clog the pores.

Most susceptible are teenagers from about ages 13 to 17.

Symptoms include blocked pores that may appear flat and black on the surface, because the oil darkens when exposed to the air; blocked pores that appear white on the surface because they have closed over with dead skin cells; or swollen, yellow-white, pus-filled blisters surrounded by reddened skin.

Outbreaks of pimples on the skin can interfere with quality of life, making the person self-conscious about their appearance and causing pain and discomfort in the skin. A medical provider can help to manage the condition, sometimes through referral to a dermatologist.

Diagnosis is made through physical examination.

Treatment involves improving diet; keeping the skin, hair, washcloths, and towels very clean; and using over-the-counter acne remedies.

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

Severe skin abscess in the armpit

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"). If the infection begins to spread, urgent treatment is required.

Rarity: Rare

Top Symptoms: fatigue, fever, painful armpit lump, pink or red armpit bump, marble sized armpit lump

Symptoms that always occur with severe skin abscess in the armpit: pink or red armpit bump, red bump

Urgency: Hospital emergency room


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

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

Mononucleosis infection

Infectious mononucleosis, also called "mono" or "kissing disease," can be debilitating for a while but is usually not dangerous in itself.

Several viruses cause mononucleosis. It spreads easily through saliva and other body fluids. Sharing a drinking glass or a spoon, or kissing someone who has the virus – even they show no symptoms – will transmit the disease. It can also be sexually transmitted.

Due to lifestyle, teenagers and young adults seem to be the most susceptible.

Symptoms include tiredness, sore throat, fever, rash, body aches, swelling in the neck and armpits, and sometimes swollen liver and spleen. The symptoms alone are usually enough for the doctor to make a diagnosis.

Because mononucleosis is caused by a virus, antibiotics will not help. Treatment consists of bed rest, fluids, and good nutrition. The patient should still be under a doctor's care due to the risk of secondary infections or damage to the heart, liver, and spleen.

Handwashing, cleanliness, not sharing dishes or drinking glasses, and not having unprotected sex are the best ways to prevent mononucleosis.

Rarity: Common

Top Symptoms: fatigue, headache, loss of appetite, abdominal pain (stomach ache), cough

Urgency: Primary care doctor


Lymphangitis is a condition resulting in inflamed lymphatic vessels due to an infection. The lymphatic system runs throughout the body and consists of both nodes and these vessels. The nodes produce lymph — the clear fluid that bathes and nourishes the organs and other tissues — while the vessels cir..

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How and When to Treat Sore Armpit Lumps

Most causes of a painful armpit lump are not immediately dangerous. However, an infection may require urgent treatment to prevent it from spreading to the rest of the body.

When it is an emergency

Seek emergency treatment if you experience the following in addition to your painful armpit lump.

  • Systemic symptoms: Such as fever and chills
  • Signs of infection: Such as redness, warmth, and drainage in the area of the armpit lump or at the site of an injury on the same arm

In some cases, even though emergency care isn't necessary, you may need evaluation and treatment.

When to see a doctor

Make an appointment with your doctor for the following.

  • The lump worsens: Your painful armpit lump fails to resolve or becomes larger and more painful over time.
  • You have foul-smelling drainage from the armpit
  • You have other symptoms: Such as fatigue, weight loss, night sweats, and/or swollen lymph nodes throughout the body.
  • You have an armpit lump that is only painful after you consume alcohol
  • You have recurrent ingrown hairs: Particularly if you notice darkening and scarring of the skin

Medical treatments

Your doctor may prescribe one or more of the following treatments, depending on the cause of your symptoms.

  • Oral or topical antibiotics: To treat an infection
  • Oral anti-inflammatory medications
  • Referral to a dermatologist or surgeon: If first-line treatments are not effective.

At-home treatments

Some home treatments may help with a painful armpit lump.

  • Minimize exposing the armpit to sweat: Shower immediately after working out and avoid tight clothing.
  • Avoid shaving the armpit: If you do continue shaving, clean and dry the skin before and after shaving and try shaving in different directions to see which way reduces ingrown hairs.
  • Try warm compresses and/or warm baths: For relief of painful skin conditions

Questions Your Doctor May Ask About Painful Armpit Lump

  • What color is the bump?
  • Any fever today or during the last week?
  • Is there fluid coming out of the bump?
  • Do you have a rash?

Self-diagnose with our free if you answer yes on any of these questions.

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