Most armpit pain is a sign of overexertion or infection. Usually, armpit pain is a result of muscle strain. Occasionally, however, it can be due to an underlying disease.

This article covers the common causes of armpit pain, when to speak with a doctor, and how to treat the pain when it occurs.

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The armpit is the hollow underneath the shoulder joint. It is also called the axilla.

The armpit is the point where the muscles that move our arms and shoulders connect with the bones. Some of these muscles also connect to the ribs.

Major nerves and blood vessels also pass through the armpit, and it is home to several lymph nodes. Swollen lymph nodes usually indicate that a person is fighting an infection, but sometimes, they can be a sign of cancer.

The skin is thin under the arms and contains a large number of sweat glands. The warm, moist conditions may increase the likelihood of fungal or bacterial infections or rashes due to chafing.

Many factors either contribute to or cause armpit pain, including some skin issues, infections, and immune conditions.

This section will look at the possible causes of armpit pain.

Muscle strain

Doctors describe muscle strain as an injury to the muscles or tendons. The fibers in the muscles and tendons may simply overstretch, or they may tear.

People taking part in sports and activities that involve lifting, pulling, or throwing, may injure muscles and experience armpit pain.

Strained pectoral, or chest, muscles — which people use for lifting and pulling — can often cause underarm pain.

Damage to the coracobrachialis muscle, or upper arm muscle — which assists people in throwing and pushing motions — may also cause armpit pain.

Swollen lymph nodes

Lymph nodes are part of the body’s immune system. They filter foreign bodies, including bacteria, and stimulate the release of immune cells, which destroy and remove these invading bodies.

During infections, the lymph nodes fill with harmful cells and begin to swell.

This enlargement causes inflammation and pain.

Causes of swollen lymph nodes include:

Swollen lymph nodes usually go down within a few days or weeks. If the swelling lasts for more than 4 weeks, a person should contact a doctor.

Allergens and skin irritants

Many deodorants, antiperspirants, body washes, soaps, and laundry detergents contain skin irritants and allergens.

Some of these may lead to allergic contact dermatitis, a condition that causes itching, burning, and tiny blisters. People usually get the rash a day or two after coming into contact with the allergen.

Irritant contact dermatitis can result in an itchy rash, stinging, pain, swelling, and heat. As the reaction is almost immediate, people quickly learn what is irritating their skin.

Bacterial and fungal infections

Ringworm, or tinea corporis, is a common fungal infection affecting the uppermost layer of skin. It triggers a red, ring-shaped rash.

As fungi thrive in warm, moist environments, the armpit is an ideal location for the infections that the fungi can cause.

Ringworm fungi also use the keratin present in hair as food. Ringworm rashes can be painful and lead to inflamed, itchy, and scaling skin.

Bacteria also flourish in moisture and warmth, so bacterial infections can develop quickly and contribute to inflammation and pain in the area.

Intertrigo

Friction and moisture in the folds of the skin can lead to a type of inflammation called intertrigo. Symptoms of intertrigo include itchy skin, pain, tingling, and burning in the affected area.

Without treatment, secondary bacterial or fungal infections may also develop, causing further pain.

Candida is a type of yeast that can cause intertrigo. It turns the skin red and causes the development of white plaque.

Heartburn

Heartburn, in which stomach acids travel back up the esophagus — or the pipe down which food travels — can cause shooting, sharp chest pain and, less commonly, pain in the armpit.

Cysts

Cysts are painful lumps that can develop when body fluids build up in the armpits.

They can become infected, especially by Staphylococcus bacteria, which usually live on the skin.

Cancer

The lymph nodes in the chest, including those in the armpits, often work extremely hard when cancer develops in the upper body.

In particular, painful lymph nodes may accompany breast cancer, lymphomas, and respiratory cancers.

Some people may also experience painful lymph nodes as a side effect of cancer treatments, such as radiation therapy, chemotherapy, and surgery.

Cancers that commonly cause armpit pain include:

  • lymphoma, or cancer of the lymphatic system
  • leukemia, or cancer of the blood-forming tissues, including the lymphatic system and bone marrow
  • cancers that have spread from another part of the body, including breast cancer, which develops nearby

Lipomas

A lipoma is a lump of fatty tissue that feels rubbery. A person can move it around under the skin. Most lipomas are noncancerous and do not cause pain.

However, lipomas that grow rapidly can cause pain by putting pressure on the nerves or blood vessels. In these cases, doctors may recommend surgery to remove the growth.

Boils or ingrown hairs

When inflammation occurs in a single hair follicle, a boil or furuncle may develop. Boils are red, swollen lumps that are tender to the touch.

When neighboring hair follicles become infected, the underlying tissue may feel inflamed and painful.

Diabetes

Diabetes can give rise to neuropathy, or nerve damage, causing burning pain in the affected body part.

Diabetic neuropathy may develop in people whose blood sugars are consistently too high.

Some autoimmune conditions

Lupus is a long-term autoimmune condition that causes inflammation throughout the body, including in the lymph nodes.

Rheumatoid arthritis is another example. This condition can lead to swelling and inflammation of the inner tissues of the joints, which may affect the armpit.

Psoriasis is an autoimmune condition that has effects on the skin in various parts of the body, including the armpit area. It can lead to different types of plaque or scale developing on the skin, as well as itching, discomfort, and pain.

Hidradenitis suppurativa

This is a chronic condition that causes inflammation of the sweat glands beneath the hair follicles. It often affects the armpits and groin, as the skin rubs together.

Symptoms usually begin as pimple-like bumps or blisters that turn into cysts and boils. Eventually, these wounds may burst and leave scars as they heal.

Shingles

Shingles causes a painful and scaly rash that often affects the chest, back, and armpits.

The rash usually clears within 7–10 days.

Peripheral artery disease

Peripheral artery disease narrows the blood vessels carrying blood away from the heart. It is more common in the legs but can affect the arms.

Arteries carry oxygen-rich blood to the muscles. Without oxygen, muscle cells begin to wither and die, which can cause intense pain.

Different conditions cause different symptoms, including skin rashes, lumps and swelling, and pain when moving.

Armpit pain on its own may not need medical attention. However, if it continues for more than 1–2 weeks, a person may consider speaking with a doctor.

People with weakened immune systems may need to consult a doctor earlier to reduce the risk of infection.

Swelling or lumps around the collarbone and armpit may be a sign that breast cancer has spread to the lymph nodes. Occasionally, this is the first sign of the disease.

Doctors may recommend a biopsy to find out if the nodes are cancerous. If they are, doctors often perform surgery to remove them. People typically have between 20 and 30 lymph nodes in each armpit, and surgeons generally remove fewer than 20.

If the lymph nodes are cancerous, there is a strong chance that the cancer has spread to other parts of the body.

People should seek medical attention if armpit pain becomes severe or interferes with daily life.

People should consult with their doctor if they have:

  • swelling in the lymph nodes that lasts for more than 1–2 weeks without a known cause
  • extremely sore armpits or lymph nodes that are tender to the touch
  • swelling on multiple lymph nodes across the body, such as in the groin, head, and neck
  • fever and night sweats
  • hard lumps in the armpit region or lymph nodes
  • swallowing and breathing difficulty
  • unexplained weight loss
  • unexplained, continuous exhaustion
  • lingering skin infections
  • abscesses or boils, or other painful skin rashes

If armpit pain occurs with lumps and soreness in the area, it may indicate serious infections or an immune condition.

Very rarely, underlying health complications can cause armpit pain. These include:

Doctors may perform a physical exam to discover the cause of a person’s armpit pain.

People with skin rashes may need to see a dermatologist for further tests.

Most people with muscle strains will not need additional tests, but doctors may recommend ultrasound or MRI scans if the damage is severe.

Doctors may recommend a biopsy if they suspect a person’s swollen lymph nodes are cancerous.

A person can soothe or prevent armpit pain by:

  • using a cold compress to reduce muscle soreness
  • taking over-the-counter anti-inflammatory medications such as ibuprofen, which are available to purchase in stores or online and can be helpful for lowering inflammation and pain
  • getting a massage, as it may help promote circulation and reduce swelling
  • using a warm compress, as this may reduce lymph node swelling and ease pain
  • using topical steroids, or antifungal or medicated creams, to treat any underlying skin conditions that cause armpit pain
  • applying moisturizers with glycerin or other hydrating properties, which can help prevent excessive dryness and related skin conditions
  • keeping the armpits clean to prevent infection
  • avoiding body washes, soaps, and detergents that contain allergens or irritants and instead using gentle, fragrance-free products
  • avoiding excessive exposure to hot temperatures, which can help prevent excess moisture and warmth in the armpits
  • taking quick, lukewarm baths and showers
  • wearing loose-fitting clothing, as this can help prevent chafing
  • not shaving the armpits too often, as doing so can cause irritation, nicks, and cuts
  • avoiding sharing personal hygiene tools or products to minimize the risk of bacterial infections

The best treatment option for armpit pain depends on the cause. If a healthcare professional suspects infection, muscle strain, or illness, they will almost always suggest rest.

Armpit pain that occurs due to cancer or any of its treatments may require anti-inflammatory and pain medications.

Controlling immune activity in conditions such as lupus and rheumatoid arthritis often helps reduce armpit pain.

Armpit pain may be the result of an accidental injury or infection and may not be completely preventable. However, people can take steps to reduce the risks of certain causes of armpit pain.

People can reduce the risk of muscle strain by warming up properly before exercising and taking care when lifting or throwing heavy objects.

People who have skin infections or rashes may be able to identify anything they are allergic to and avoid using it. Keeping the underarm area clean and dry can reduce the risk of bacterial and fungal infections.

By controlling their blood sugar levels, people with diabetes may reduce the risk of neuropathy.

Armpit pain is usually a sign of a strained muscle, minor infection, or skin condition. Very occasionally, it can be a symptom of a more serious underlying condition, such as cancer.

Some people may have rashes, boils, blisters, or sores on their skin, while others may have no visible symptoms.

People need to seek medical help if the pain is severe or interferes with their daily life.