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4 Causes of Armpit Pain

Your armpit is susceptible to irritation and skin infections.

What is armpit pain?

Your armpit experiences a lot of activity, from sweating to daily applications of deodorant to shaving. So it’s no surprise that it can have the occasional health issue. Pain can be caused by an ingrown hair or rash from a new lotion or deodorant.

But in some cases, the pain can be caused by a lymph node that’s swollen from fighting off an infection. Or from changes in breast tissue that occur during a woman’s menstrual cycle.

Most underarm pain can be treated by avoiding irritating products or using a warm compress, but some causes may need to be checked by a doctor.

Armpit pain, especially when it’s in the left arm, can also be related to your heart. Pain that radiates from your chest toward your arm may be a sign of a heart attack and should be taken seriously.

What is causing your armpit pain?

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1. Skin irritation

Symptoms

  • Rash
  • Redness
  • Pain or tenderness
  • Itchiness

Skin irritation may be caused by an ingrown hair. But irritants, like deodorant or detergent, can trigger contact dermatitis. This is an allergic reaction that causes a rash that is itchy or painful.

Changing out of damp or sweaty clothes can help avoid these issues. Try using a warm compress or stop using the products on your armpit until it goes away. If that doesn’t help, see a doctor.

The armpit, with its folds and creases, can also get bacterial skin infections, such as folliculitis or cellulitis. Folliculitis is an infection of the hair follicles under the arm. Cellulitis damages deep layers of skin and can spread. If you also have severe pain, fever, or chills, contact a doctor. You may need antibiotics to treat the infection.

2. Muscle strain

Pro Tip

The armpit is a common location for muscle strains. Strains usually occur when trying to lift a heavy object, working out too vigorously, or performing repetitive motions. The pain of muscle strains may come on quickly, if there is a sudden injury, or may develop over the course of a day or so. —Dr. Benjamin Schwartz

Symptoms

  • Swelling or bruising under the arm or on the upper rib cage
  • Tenderness at the shoulder, armpit, or upper rib cage

Lifting a heavy object, working out too intensely, or repetitive motions, such as snow shoveling, can all cause a strain in the muscles around the armpit or rib cage.

Rest, heat, and ice, can help relieve symptoms. If symptoms continue for more than 3 weeks or interfere with daily activities like washing your hair, putting on clothes, or reaching overhead, see a doctor.

3. Swollen lymph nodes

Symptoms

Lymph nodes are responsible for draining fluid and waste products from other parts of the body. They play an important role in fighting infection and may become enlarged when they trap viruses or bacteria. They may also become infected.

Swollen lymph nodes may be a symptom when you have a viral or bacterial infection. They may also become enlarged if you have a bug bite—or for no obvious reason.

You may feel a lump or bump that usually goes away in several days. If it doesn’t or if it keeps growing, becomes more painful, or you notice fluid, see a doctor.

So... which condition is actually causing your armpit pain?

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4. Angina pectoris

Symptoms

Angina pectoris causes reduced cardiac blood flow. This occurs when the arteries (blood vessels) narrow, which forces the heart to pump harder to deliver blood to the body. The pain generally doesn’t last long. A special medication called nitroglycerin can help the pain.

When the artery becomes completely blocked, it can lead to a heart attack.

Go to the ER or call 911 if you feel crushing chest pain that radiates toward the left arm and armpit. It may be accompanied by nausea, chills, and shortness of breath.

Other possible causes

Dr. Rx

Your armpit, known medically as the axilla, houses many different important anatomical structures including nerves, blood vessels, lymph nodes, breast tissue, sweat glands, and muscles. —Dr. Schwartz

A number of conditions may also cause underarm pain, although they are rare or may have additional symptoms beyond armpit pain. These include:

When to call the doctor

  • Pain that does not improve after 48 to 72 hours of home care
  • Increasing pain, swelling, or redness
  • Difficulty moving the shoulder or arm
  • Any lumps or bumps that are growing or become painful

Should I go to the ER for armpit pain?

You should go to the ER if you have any of these signs of a more serious problem:

  • Chest pain, or chest pain that radiates to your left shoulder and arm
  • Fever above 101.5℉
  • Any area that is draining pus
  • Severe pain that makes it difficult to breathe
  • Shortness of breath

Treatments

Pro Tip

The armpit area has several different muscles, including those that attach to your rib cage, your chest muscles, and muscles that help control the movement of your arm. —Dr. Schwartz

At-home care

  • Avoid scented detergents or fabric softeners.
  • Wear tops with loose or non-restrictive sleeves.
  • Take off clothes if sweaty or damp.
  • Consider skipping deodorant until it improves.
  • To reduce skin bacteria, wash armpits before and after shaving.
  • Over-the-counter (OTC) pain relievers like ibuprofen, naproxen, or acetaminophen can help relieve muscle strain.
  • Topical OTC pain relievers such as creams, balms, or rubs.
  • Avoid activities that may aggravate the pain like reaching overhead or pulling.
  • Ice to help numb the pain and reduce swelling and/or heat to relax muscles.
  • Take note of other symptoms, such as fever or swollen glands that don’t seem to get smaller, or are tender to the touch. If symptoms exist for 10 to 14 days after at-home treatment, see a doctor.

Other treatment options

  • Physical therapy to stretch and strengthen muscles around the armpit.
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