Pain in Left Armpit: Common Causes of Pain Under Left Armpit

Pain in Left Armpit: Common Causes of Pain Under Left Armpit

Pain in the left armpit (also called axilla) can have a number of causes that can range from a simple sore pulled muscle to enlarged lymph nodes. Because we use our arms so much during the day, pain under the left armpit can affect daily activities. Many people are concerned about left armpit pain because they may worry it is connected to their heart. Or, that a painful lump in the left armpit could be a sign of cancer.

The armpit skin is very sensitive, and shaving, skin infections, or armpit rashes can easily flare-up and cause irritation. Also, an ingrown hair can cause a painful lump in the armpit, or a viral infection can result in swollen lymph nodes. Thankfully, most causes of sore armpits are harmless and the pain and discomfort go away when the underlying issue is resolved.

There are also many muscles, nerves, and ligaments in your armpits that keep your arms flexible and strong. Straining muscles in the armpit or suffering from nerve pain can cause throbbing aches or shooting pains down an arm or across your chest.

In this article, I will look at what it can mean when it hurts under your left armpit. In many cases, you will also find helpful home remedies to reduce aches and pain in your left armpit. You will also learn when the symptoms of underarm pain on the left side could indicate that there could be something more serious going on.

The Symptoms of Pain in Left Armpit

Pain under the left armpit is usually accompanied by other symptoms that can help diagnose the root cause of the pain.

For example, a viral infection can cause you to have a fever, a runny nose, and enlarge nodes in the armpit that may be sore. An inflammatory skin condition like eczema or psoriasis will cause an itchy red armpit rash that becomes sore with chaffing.

Other symptoms of pain in the left armpit can include:

  • Pain, weakness, or tingling down the left arm due to damaged muscle or nerve
  • Redness, small red sore bumps, and skin irritation caused by waxing or shaving
  • Large painful nodules that ooze pus-like discharge
  • A cyst or enlarged lymph node that may or may not be painful
  • Shooting, electric-like pains that go down the left arm or across to the left chest
  • Swelling of the upper arm and shoulders
  • Burning sensation in the chest caused by acid reflux

Of course, it is normal to feel a measure of anxiety with armpit pain. Because squeezing chest pains that spread to the left arm and jaw could be signs of a heart attack, you should never ignore this type of pain.

Causes of Pain Under Left Armpit

Let’s look in more detail at various causes of a sore left armpit and what you can do to get rid of the armpit pain naturally.

Pulled / strained muscle or tendon

Pulling or straining a muscle or tendon in your left arm can result in sharp pain in your armpit and shoulder blade.

Researchers from the Cleveland Clinic say that your biceps are located in your upper arm. Overuse arm injuries can cause your upper arm and chest to hurt and throb. In severe cases, a traumatic injury to your left arm or chest could tear one of the tendons resulting in searing pain in the left armpit.1

According to doctors from the American Academy of Orthopedic Surgeons, repetitive strain injuries are the most common reason for biceps tendonitis. Other symptoms can include:2

  • Armpit pain that intensifies when lifting or throwing an item
  • Aching discomfort in the left arm bone
  • Feeling a snapping sensation in the shoulder

Usually, getting proper rest and using cold packs can help to resolve aching pain caused by a pulled muscle. If you have pulled or stretched a muscle in your back, you can also use natural remedies to get rid of muscle soreness.

Skin irritation or rash

The skin of the armpit is very sensitive and the moist dark environment of the armpit means that rashes or skin irritation is common. Inflammation, bacterial infections, or fungal infections can easily affect either armpit making it sore and itchy.

Psoriasis. This is a skin condition that often causes a painful rash in the armpit of both men and women. According to doctors from the Mayo Clinic, some types of psoriasis commonly affect the armpits. This results in inflammation and patches of sore red skin in the armpit that get easily irritated.3

You can try these natural ways to relieve psoriasis to help manage the symptoms of underarm psoriasis.

Yeast infection. Yeast or fungal infections that affect the left armpit and can cause a painful rash. Dr. Denise M. Aaron in MerckManuals says that a yeast skin infection can also cause scaling, itching, and swelling. It’s important to keep the armpit as dry as possible and apply an antifungal ointment to clear the infection.4

You can use a mixture of coconut oil and tea tree oil as a natural antifungal cream to apply to your itchy armpit skin, or apply diluted apple cider vinegar as an effective home remedy that you can use to treat armpit yeast infection.

Bacterial skin infection. Dr. Carol DerSarkissian on WebMD reports that bacterial infections can affect the hair follicles of the armpit, resulting in painful red bumps. Sometimes, the infection can go deeper causing a very sore inflamed red lump in the armpit.5  

You can get rid of a bacterial armpit rash by applying some aloe vera gel to reduce itching and repair skin damage.

Eczema. According to Prof. Amanda Oakley, a dermatologist in New Zealand, dermatitis (eczema) can cause a painful itchy red patch to flare up in the armpit. This red armpit rash may also have flaky bits of scaly skin.6

Witch hazel has anti-inflammatory properties that can help to reduce the severity of eczema symptoms. You can find other natural ways to treat eczema in my article on 13 natural remedies for eczema or try these top 12 essential oils for eczema.

Intertrigo. Intertrigo is an inflammatory skin condition that affects folds of the skin and commonly causes an irritating armpit rash. Chaffing of the armpit skin can aggravate the sore condition and even cause a secondary infection to develop.7

Make a paste of colloidal oatmeal and apply to the irritated patch of skin in your armpit to reduce itching and irritation.

Waxing or shaving the underarm

If you regularly shave your underarm hair, you might find that irritation and swelling can develop in either or both of your armpits.

The International Journal of Cosmetic Science found that removing armpit hair can cause pain and discomfort because shaving also removes skin. Researchers found that swollen red marks and painful flare-ups are common in shaved armpits.8

Find out how to reduce friction while shaving your armpits in my article on how to get rid of razor burns naturally.

Hidradenitis suppurativa

If you have large sore nodules and pain in your armpit, it could mean that you suffer from a condition called hidradenitis suppurativa.

Dermatologists say that hidradenitis suppurative can cause boil-like lumps in the armpit. Very often, these firm papules can be very sore and sometimes pus-like fluid can drain from them. Managing the symptoms of hidradenitis suppurativa can be a challenge. However, dermatologists suggest following an anti-inflammatory diet and losing excess weight to help to reduce pain.9

Arm artery disease (peripheral artery disease)

A persistent ache in your armpit could be an indicator that you have a type of peripheral artery disease (PAD) that affects the arm.

PAD describes a condition were small arteries become narrowed and reduce blood flow. When it affects the arteries in the armpit and arm, it is called arm artery disease. Doctors from the Ohio State University say that symptoms of arm artery disease can include:10

  • Discomfort or pain in one or both of your arms
  • Cramping feeling in the affected arm
  • Loss of feeling in the arm
  • One or both arms that have pale, reddish blue skin and is cool to touch

Looking after your cardiovascular system is the best way to prevent PAD and its associated symptoms. This will also help greatly reduce your risk of a heart attack and improve your blood circulation.

Sharp Shooting Pain in Armpit

Some medical conditions result in a sudden sharp pain in the left armpit that could even startle you.

Intercostobrachial neuralgia (armpit nerve pain)

Your armpit is home to a series of nerves called the brachial plexus which run between your left and right arm and your ribcage. Damage to the intercostobrachial nerves can cause severe shooting pains in your armpit and chest.

According to the journal Regional Anesthesia and Pain Medicine, damage to the nerves in your armpit is often a result of surgery to the upper chest or breast.11 Armpit nerve damage can cause a dull, throbbing ache which can suddenly become sharp and painful.12

Brachial plexus injury

A feeling like an electric shock in your armpit that travels down one arm could be due to a brachial plexus injury.

Doctors from the Mayo Clinic say that brachial plexus injuries are common among sports people or as the result of an accident. Because brachial plexus injuries cause a stinging, burning underarm pain, they are sometimes called “burners” or “stingers.” The sharp, stabbing pain in your left armpit or right one may just last a few seconds or some minutes.12

A serious brachial plexus injury can result in severe pain and possibly an inability to use the arm. Treating a brachial plexus injury depends greatly on the severity of the nerve damage.

Painful Lump in Armpit – Female Only

It can be concerning for any woman to discover a lump in the armpit that is sore. What are some of the reasons for having a lump in the armpit that hurts?

Breast pain

Doctors from the National Health Service report that most lumps that appear on the body are harmless. If you have breast and underarm pain with a lump, then you should have your doctor check it out.

Times, when it is advisable to see a doctor for a painful lump, is if the armpit lump gets bigger and is sore or you have swelling in your armpit.13

It’s reassuring to know that most causes of breast pain are more an inconvenience rather than something to worry about. Many women experience sore breasts after their period or before. Pain under the breast  can also be associated with gallstones, indigestion, or a result of being under emotional stress.

Breast cancer

If you discover a new lump in your armpit or breast, you should get it checked out by your doctor. Pain under the left armpit and down an arm can, on rare occasions, be a sign of breast cancer.

According to the American Cancer Society, there are a number of noncancerous conditions that cause lumps. However, armpit lumps can sometimes be a sign of cancer and may appear before any lump in the breast.14

Painful Lump in Armpit – Female and Male

Let’s look in some detail at what a painful lump in your armpit can mean for both men and women.

Cyst in armpit

One cause of underarm pain of the left arm is if a cyst develops and presses on a nerve in your armpit.

The journal Tumori reported on cases where people attended their doctor because of a tender cyst in their armpit. It was discovered that out of 30 people, 4 had an armpit cyst and one had a lipoma (a buildup of a fatty mass).15

Swollen underarm lymph nodes

A sore, painful lump in your left armpit may be caused by an enlarged lymph node that causes a visible lump.

Dr. John P. Cunha on eMedicineHealth reports that lymph nodes are found in the armpits, neck, and chest. Lymphadenitis (inflammation of the lymph nodes) can often occur if the body is fighting a virus. If you have injured your left arm, you might discover that a lump in the armpit develops.16

Lymphoma (lymphatic cancer) can also cause lymph node swelling. The soreness under the left armpit can develop if the lump presses on a nerve.17

If the armpit lump doesn’t go away after 2 weeks or you develop a sore lump in your armpit, you should see a doctor.

Ingrown hair

A sore lump under your armpit may be the result of an ingrown hair that has become inflamed and painful.

Doctors from the Mayo Clinic report that ingrown hairs that form into a sore bump are common in the armpit. Very often, the lump can become sore and itchy and fill with pus. Usually, shaving in the direction of hair growth and lubricating the underarm can help to prevent ingrown hairs in your armpit.18

Pain Under Left Armpit and Shoulder

What can it mean if your armpit and shoulder hurt?

Dislocated shoulder

If you have dislocated your left shoulder, you will have no doubt that the intense, agonizing pain in your upper left arm and shoulder is due to the dislocation.

According to doctors from the American Academy of Orthopedic Surgeons, dislocating your shoulder can also tear ligaments or tendons in your armpit and shoulder. Usually, the severe pain goes away when the arm is put back into place.19

To prevent permanent damage to the shoulder and upper arm, it’s important to follow your doctor’s advice on rehabilitation. This usually requires restricting movement of the arm and then strengthening muscles in the arm.

Other reasons for left armpit and shoulder pain

If you have pressing chest pains that cause your left armpit to become sore and then spreads to your shoulder, it could be one of the signs of a heart attack.

Pain Under Left Armpit and Chest

Sharp pain under your armpit that also cause chest pains could be related to internal organs, or medical conditions unrelated to your arm.

Acid reflux (heartburn)

Heartburn occurs when acidic stomach fluid escapes back up the esophagus causing a burning sensation in your chest. According to Dr. Sabrina Felson on WebMD, the sharp, burning sensation can also spread to your arms, cause shoulder pain, or make your neck sore.20

Try some natural antacids for heartburn to help get rid of acid reflux symptoms quickly. For example, taking a glass of water with ½ teaspoon baking soda can help to neutralize the acid in your digestive system.


Intense tingling pain in your armpit along with a blistering rash could be a sign that you have shingles.

Shingles is caused by the varicella-zoster virus and affects the nerve endings under the skin. Dr. Mary Harding on says that the pain from shingles can start as a dull gnawing pain that doesn’t give you any relief. Sometimes, if your armpit is affected, you may experience sharp shooting pains that come in waves. Your armpit skin may be tender to touch.21

Apply some Manuka honey to the sore, painful rash to help treat your symptoms of shingles naturally.

Heart-related arm pain

Your heart is situated to the left side of your chest, and most heart-related pain spreads to the left arm and armpit.

The publication Informed Health Online says that cardiac pain caused by heart disease, angina, or a heart attack causes excruciating chest pains. These squeezing pains may come and go and then radiate to the left armpit and down the left arm. Heart pain can also spread to the jaw, neck, or shoulder.22

Armpit Pain and Anxiety

Of course, armpit pain may cause a degree of anxiety until you find the source of the pain. However, anxiety itself can also affect every part of your body, including your armpit, upper arm and chest. The Journal of Affective Disorders reports that chronic pain is common in people who suffer from anxiety and mood disorders.23

Please read this article to find out how else stress and anxiety can affect your body. Try some natural relaxation techniques such as meditation or essential oils to relieve stress and anxiety.

When to See a Doctor

Because so many different conditions can affect the armpit, it is good to know when to see a doctor if you have pain in the left armpit.

Doctors advise seeing a medical professional for armpit pain in the following circumstances:

  • The lump in your armpit feels hard and doesn’t go away after 2 weeks.
  • Sharp armpit pain is also accompanied by tingling in your arm or numbness.
  • You have a large painful boil or abscess in your underarm area.
  • You notice lumps in your breast.
  • Pain in the armpit is severe and intense and affects your daily activities.
  • Pressing chest pains spread to your left arm.

Read my other related articles:

Medical Sources

  1. ClevelandClinic. Biceps tendon injuries.
  2. OrthoInfo. Biceps tendinitis.
  3. MayoClinic. Psoriasis.
  4. MerckManuals. Candidiasis (yeast infection).
  5. WebMD. The armpit.
  6. DermNetNZ. Seborrheic dermatitis.
  7. MedicineNet. Intertrigo.
  8. Int J Cosmet Sci.2007 Feb;29(1):31-8.
  9. DermNetNZ. Hidradenitis suppurativa.
  10. WexnerMedical. Arm artery disease.
  11. Reg Anesth Pain Med.2014 Jul-Aug;39(4):272-8.
  12. ScienceDirect. Intercostobrachial nerve
  13. NHS. Lumps.
  14. CancerOrg. Breast cancer symptoms.
  15. Tumori. 1996 Nov-Dec;82(6):596-9.
  16. eMedicineHealth. Swollen lymph nodes.
  17. eMedicineHealth. Lymphoma.
  18. MayoClinic. Ingrown hair.
  19. OrthoInfo. Dislocated shoulder.
  20. WebMD. What are the symptoms of heartburn?
  21. PatientInfo. Shingles.
  22. NCBI. Coronary heart disease.
  23. J Effec Disord. 2017 Oct; 220: 1-7.

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