Why Does My Armpit Hurt?

Medically Reviewed by Shruthi N, MD on July 21, 2024
Written by Alyson Powell Key, Marijke Vroomen Durning, RN
6 min read

Pain can be throbbing, aching, or sharp, and it can be occasional or constant. It all depends on what’s causing the pain. The uncomfortable sensation is a red flag, though, a warning to you that something is wrong. If you have pain in your armpit, it could mean that you’ve simply strained a muscle, which you can usually ease with ice and rest. It could also be a sign of more serious conditions, like an infection or cancer.

It may seem odd to think “why does my armpit hurt,” but pain is pain, no matter where it is. And if you have pain in your armpit, you need to find out why so you can deal with it. One common reason for armpit pain is muscle strain.

Your armpits and the surrounding chest and arm area are made up of blood vessels, nerves, and muscles. Like other muscles in your body, you can strain muscles around your armpit by overdoing things, like lifting something heavy or with repeated movements.

Symptoms of a muscle strain depend on how serious the strain is. They can include:

  • Pain or tenderness, especially after movement that stretches the muscle
  • Redness or bruising
  • Muscle twitching or spasm
  • Swelling

For mild strains, doctors suggest that you rest the muscles by taking a break from the activity that caused the pain. You can also put ice on the area and take an over-the-counter (OTC) medicine to ease pain and swelling. Call your doctor if your symptoms get worse or the strain doesn’t heal within a few weeks.

Lymph nodes are small bean-shaped organs found throughout your body. They’re connected to each other by lymph vessels. The lymph nodes filter lymph fluid, which contains many cells, including proteins, fats, white blood cells, cancer cells, bacteria, viruses, and many more. The lymphatic system is part of your immune system, so the lymph nodes help fight infections and other illnesses. Adults have around 600 lymph nodes throughout their body, but the ones people have heard of the most often are inthe neck, groin, and armpits. If lymph nodes become swollen and painful, it could be a sign that you’re fighting an infection such as: 

Swollen and painful lymph nodes caused by an infection usually improve when the infection goes away. In the meantime, to feel better, you can:

  • Place a warm, wet washcloth under your armpit over the tender area.
  • Take over-the-counter pain medicine.
  • Get plenty of rest.
  • Take antibiotics or antivirals if prescribed by your health care professional.

Your armpits are at risk of irritation for a few reasons, and they can cause allergic contact dermatitis, which can cause redness, pain, itching, and blisters:

  • Deodorants or antiperspirants 
  • Soaps and detergents
  • Shaving cream
  • Sweat

If you have allergic contact dermatitis, try switching the products you use, and clean your armpit well before and after using them.

You could also have skin irritation and redness from:

  • Shaving
  • Rubbing – skin to skin as you move your arms, or from clothing

Why do bumps under armpits hurt?

Bumps in your armpit can be more than just irritation. They could be an abscess or cyst. An abscess is a small pocket that is filled with pus. A cyst is a small sac that can have fluid in it, but it also can be hollow or hard.  

One type of abscess is called hidradenitis suppurativa, or HS. It’s also called acne inversa. These appear in areas where skin rubs together, including armpits. If it becomes painful, doesn’t go away, or keeps coming back, you should see your doctor for treatment. You may need antibiotics or other medications, like corticosteroids or hormonal therapy.

Cysts might form if you have an ingrown hair. Unless there are signs of an infection (such as redness, increasing pain, or fever), you can try treating this at home before seeing a doctor. First, don’t shave the area. Let the hair grow out for a while. You can apply a warm, wet cloth or compress to your armpit a few times a day for 10 to 15 minutes. This can help your skin pores open and eventually release the ingrown hair or hairs.

When you do shave again, an electric shaver is better than a razor for your skin. Or you may want to try depilatory creams instead, so you don’t have to shave at all.

Autoimmune conditions such as rheumatoid arthritis (RA) and lupus can cause swollen lymph nodes. Other diseases that can do this as well include:

A lump in your armpit is not normal, so it should be checked by a doctor. In some cases, it could be a sign of cancer, such as:

Adult soft tissue sarcoma

This type of cancer affects your body’s soft tissues, like the muscles, tendons, and fat cells. It’s a rare form of cancer that may show up as a fast-growing lump. It can happen in the armpit.

Breast cancer

One possible symptom of breast cancer is pain and swelling in your armpit. It may come from:

  • The spread of breast cancer to your lymph nodes
  • Lymph nodes themselves

The swelling and pain may come before you feel a lump in your breast.

Leukemia

Leukemia is a blood cancer, and there are many types. It happens when cancerous cells in your bone marrow don’t allow the marrow to make enough red blood cells. 

Because there is no tumor, like with breast cancer or sarcoma, sometimes it can take a while for someone to be diagnosed with the disease. One of the symptoms of leukemia is swollen lymph glands. If you have leukemia, you may notice a lump in your armpit, which is the swollen gland.

Lymphoma

Lymphoma is another type of blood cancer that affects the lymphatic system. There is Hodgkin's lymphoma and non-Hodgkin's lymphoma. It starts in the white blood cells, the type of blood cells that usually fight infections. 

Like leukemia, there are no tumors with lymphoma. One of the symptoms is lymph node swelling.

Since swollen lymph nodes could be caused by something serious, it’s important to see your doctor if yours:

  • Happen for no known reason
  • Continue to grow
  • Don't get better after 2 weeks
  • Feel hard or rubbery, or don't move when you press them
  • Come with a fever, night sweats, or weight loss that you can’t explain

If you have armpit pain, think about what you might have been doing recently. Have you switched detergents or soap, or have you shaved recently? Have you lifted anything heavy, done more exercise than usual, or gotten hurt? These could be causes of armpit pain. If you’ve been feeling sick with a cold or some other illness, this also could be a cause. If the pain or lump doesn't go away within a couple of weeks, or if you start having other symptoms, like a fever, sweating, or the pain gets worse, see your doctor as soon as possible. It could be a sign of something serious.

Can armpit pain be hormonal?

Yes, armpit pain can be related to your menstrual cycle. Your breasts can become tender overall, and that includes the tissue just under the arm. Some people find it gets worse when they are in perimenopause and later, especially if they take hormone replacement therapy.

Can stress cause armpit pain?

Physical stress, like overusing your muscles, can cause armpit pain.

Why do my armpit lymph nodes hurt?

The lymph nodes in your armpit could become swollen and tender if you have an infection or some other illness that is causing the swelling.

What should I do when lymph nodes in my armpit hurt?

If your lymph nodes are swollen and painful, see your doctor to rule out any serious illnesses.