What causes armpit pain? Related conditions and treatments

You may not think much about your armpits at all—that is, until something goes wrong. If you’re not expecting pain in your armpit, you may be a little taken aback. The pain could be the result of any number of causes and can vary by cause and in severity. 

“There’s not a one-size-fits-all treatment,” says Jay W. Lee, MD, a family medicine physician and member of the board of directors for the American Academy of Family Physicians.

In order to treat armpit pain, you need to know the cause. So, if you develop new pain in your armpit, and the pain seems to be getting worse or you’re developing additional symptoms, checking in with your doctor can get the ball rolling. In the meantime, we’ll discuss the most common causes of pain in the armpit.

Key takeaways:

• Armpit pain is a fairly common symptom with a number of potential causes.
• Typically, armpit pain does not require immediate medical attention, but it depends on the cause of the pain. Read more about treatments for skin tags, hidradenitis suppurativa, and shingles. 
• Armpit pain can be managed with cold compresses, rest, and sometimes medication. 

What causes armpit pain?

Wondering what’s causing that pain in your armpit area? It could be any of a number of causes, such as swollen lymph nodes, a pulled muscle, and dermatitis, among others. 

Swollen lymph nodes

A viral infection like mononucleosis or the flu can lead to swollen lymph nodes under the arm, which can be tender or even a little painful. The lymph nodes tend to swell when they react to an infection or a vaccine. You may even notice armpit pain after a COVID-19 vaccine. If you have pain in the left armpit, and that’s the same arm you had your vaccine, it could simply be a sign that your immune response has kicked in and the vaccine is working.

Although lymph node swelling may lessen as you recover from your illness or within a couple of days of getting a vaccine, you should see a doctor for swollen lymph nodes if they grow in size, have been present for two to four weeks, are accompanied by persistent fever, night sweats, or unexplained weight loss, or feel hard or rubbery. Hard, fixed, rapidly growing nodes can be a symptom of cancer and lymphoma.

Contact dermatitis

Exposure to allergens such as deodorants, fragrances, plants, jewelry, detergents, soaps, and certain chemicals can cause an itchy rash to develop under the arm. This type of rash is known as contact dermatitis—caused by direct contact with a substance or an allergic reaction to a substance. For example, using a new detergent for laundry may result in some itchy redness where the clothing comes into close contact with the skin in the armpit. This can cause pain or even lead to a secondary infection if rubbed or scratched in an attempt to relieve the itching. Although it may be uncomfortable, contact dermatitis is not contagious.

Growths

“Growths such as cysts, skin tags, and moles can also cause pain when they’re inflamed,” says Brendan Camp, MD, a dermatologist with MDCS Dermatology in New York. For example, a skin tag or mole can become irritated if it rubs up against clothing or another item, like a seat belt or purse strap. Growths can also cause pain in the armpit if you accidentally nick it while shaving. 

Muscle strain

Injuring a muscle or tendon can lead to muscle strain. Activities that involve lifting, stretching, throwing, and pulling may result in a muscle strain to the armpit area, which can cause some pain when you move your arm. Resting the arm can provide time for the muscle to recover from the strain and resolve any pain in the armpit.

Ingrown hair

Hair that grows back into the skin after shaving, waxing, or plucking the armpit area can cause a painful lump or bump. It might look like a pimple at the site of a hair follicle. Also known as pseudofolliculitis, this inflammation is more common in people who have curly hair. 

Bacterial or viral infections

Bacteria and viruses can both cause pain in the armpit in certain circumstances. “For the most part, it’s bacterial infections that we worry about,” says Dr. Lee, explaining that bacteria can get into a cut from shaving or even an ingrown hair, which could lead to a serious infection like cellulitis. According to Johns Hopkins Medicine, the bacteria that are most likely to cause cellulitis are staph and strep bacteria. 

Shingles

Shingles is one particular viral infection that could cause armpit pain. The varicella-zoster virus, which causes chicken pox, also causes shingles, a painful infection that causes a rash that usually occurs on one side of the body, although it can also be more widespread in people with weakened immune systems.

Fungal infections

Fungal infections can also cause itchiness and pain in the armpit area. For example, a yeast infection, or candidiasis, can develop under the arm, where it’s moist and warm. So can ringworm, a common fungal infection that causes a circular red rash that can become itchy and possibly a little sore. 

Hidradenitis suppurativa

Painful lumps, boils, cysts, and sores in the armpit area could be a symptom of a painful skin condition called hidradenitis suppurativa, or acne inversa. It’s a chronic condition, and although it isn’t curable, it is treatable. If left untreated, abscesses can develop, break open, and leak blood and pus. 

Inverse psoriasis

Inverse psoriasis is an autoimmune condition that tends to develop in skin folds, such as the armpit, groin, and under the breasts. You might notice red, purple, or brown lesions in those areas, and they can be very irritating and painful. 

Should I be worried about armpit pain?

“Unless severe pain, a fever, nausea, or other symptoms develop, it’s probably not necessary to rush off to a doctor or an urgent care center,” Dr. Lee says. It might be worth applying warm compresses to the area for a day or so to see if that helps. “Waiting overnight is never a bad idea if it’s not excruciating.”

But, Dr. Lee pays close attention to underlying medical issues that his patients may have, such as diabetes and other chronic health conditions. In that case, he might want to be more vigilant about infections.

Some people may worry that a lump, bump, or swollen lymph node under the arm could be a sign of breast cancer. According to Dr. Patricia A. Ganz, MD, a professor at the UCLA Field School of Public Health and the David Geffen School of Medicine at UCLA, there’s not too much to worry about—at least on the cancer front. “Painful lumps are almost always associated with an infection,” Dr. Ganz says. “A swollen lymph node in the armpit, either from breast cancer or lymphoma, is rarely, if ever, painful. They are asymptomatic.”

However, if a lump in the armpit is painful, the best course of action is to consult a doctor. “The acute onset of a lump could be a sign of infection that warrants treatment. But if the painless lump lingers, that could be an impetus for evaluation and a needle biopsy to rule out a malignancy,” says Dr. Ganz. 

In general, if you’re not sure what causes the armpit pain that you’re experiencing, talk to your doctor so you can get a diagnosis. Using the right treatment will give you the best chance to get rid of the armpit pain. 

How is the cause of armpit pain diagnosed?

If a patient came to him with complaints about pain in the armpit area, Dr. Camp says he would start the diagnostic process by asking some questions. 

“Assessing an underarm issue requires first taking a careful history from the patient to determine the duration of the issue, associated symptoms, potential triggers, and any treatments that have already been tried,” Dr. Camp says.

Dr. Lee agrees that he would begin a visit by taking a thorough patient history. He would start by asking a patient to describe any symptoms that concern them. He would inquire about their history, asking questions such as:

• Have you recently traveled where you could have picked up an infection?
• Have you experienced any trauma or injuries to your armpit or surrounding muscles?
• Have you been sick recently?

Additionally, a doctor might feel compelled to run some tests. For example, a skin sample and some blood work can help determine whether the cause of the armpit pain is a cellulitis infection. A bacterial culture can pinpoint the specific bacteria that caused the infection and provide valuable information for choosing the right antibiotic to treat the infection. 

How long does armpit pain last?

It’s hard to put a timeframe on how long armpit pain can last because it depends on the cause. Someone with a chronic illness like hidradenitis suppurativa or inverse psoriasis may experience ongoing or recurrent pain in the armpit area. 

But, someone who experiences pain due to an infection might find that the pain lessens once they begin treatment. 

How to treat armpit pain

Treating armpit pain depends on the cause of the pain. For example, armpit pain treatments for pain caused by inverse psoriasis might include corticosteroid creams or topical treatments. However, if those don’t work, a healthcare provider may prescribe oral medications, such as methotrexate or acitretin, or injectable medications, such as adalimumab, etanercept, or infliximab.

If you suspect that your armpit pain or rash is caused by contact dermatitis, you can switch back to your old deodorant or detergent, and in the meantime, apply cool, wet compresses to your armpit. If that doesn’t alleviate the pain, you could use an over-the-counter (OTC) anti-itch cream like hydrocortisone to soothe the skin. Hydrocortisone cream can only be used for a limited number of days in the armpit, and strong corticosteroid creams are typically avoided in this area and other skin folds.

“Pain from more straightforward causes, such as irritation from shaving, may respond to at-home treatments, such as OTC hydrocortisone cream or an ice compress,” Dr. Camp says. “Pain or skin changes that impact the quality of your life, do not respond to at-home treatments, or are associated with other symptoms should be addressed by a board-certified dermatologist.” 

Living with armpit pain 

If the cause of the armpit pain is easily treatable, you may not have to worry about living with it for very long. An antibiotic may knock out a bacterial infection, for example, and a doctor can remove an inflamed skin tag. 

However, living with a chronic condition that causes pain, such as hidradenitis suppurativa, may require some long-term coping strategies. Pain can make it hard to sleep, concentrate, and connect with other people. The American Academy of Dermatology recommends these tips for hidradenitis suppurativa:

• Treat painful lumps with black tea or warm water compresses.
• Take steps to reduce sweating, which can aggravate the pain and discomfort.
• Wash your armpit skin gently since scrubbing can worsen inflammation.
• Consider laser hair removal to remove armpit hair follicles so there is less to become occluded.
• Follow your doctor’s wound-care treatment plan if you have open lesions.
• Use a mild deodorant that doesn’t cause further skin irritation.

Most importantly, see a doctor if the pain worsens or you develop other symptoms

Armpit pain causes vary widely but include bacterial infections, viruses like the varicella-zoster virus that causes shingles, muscle strain, and chronic conditions such as hidradenitis suppurativa. The cause of armpit pain may resolve on its own without treatment. However, if armpit pain continues, worsens, or is accompanied by fever and swelling, it could be a sign of infection and require treatment such as antibiotics, antivirals, or antifungal medication. Only your healthcare provider can rule out infection or other serious health conditions. Visit your doctor to determine the best treatment for armpit pain.