Why Does My Armpit Hurt?

Medically Reviewed by Jabeen Begum, MD on April 19, 2023
3 min read

Whether it’s throbbing, aching, or sharp, everyone has been in pain. The uncomfortable sensation is a red flag. Pain in your armpit could mean that you’ve simply strained a muscle, which you can ease with ice and rest. It could also be a sign of more serious conditions, like an infection or breast cancer.

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 armpit muscles by overdoing things, like lifting something heavy. 

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 muscle 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 medicine to ease pain and swelling. Call a doctor if your symptoms get worse or the strain doesn’t heal within a few weeks.

Lymph nodes are found in many areas of your body, including your neck, groin, and armpits. If they’re swollen and painful, it’s usually a sign that your body is fighting a viral infection such as:

Less commonly, lymph node infection can be caused by: 

  • Tuberculosis 
  • Sexually transmitted infections such as syphilis
  • Toxoplasmosis (infection with a parasite that happens when you eat undercooked meat or come into contact with the feces of an infected cat) 
  • Cat scratch disease (infection from a bite or scratch from a cat infected with the Bartonella henselae bacteria

Autoimmune conditions such as rheumatoid arthritis (RA) and lupus can also cause swollen lymph nodes. 

When your lymph nodes swell, you may also have a runny nose, sore throat, fever, and night sweats.

Pain due to infection goes away when the condition causing it gets better. In the meantime, to feel better:

  • Place a warm, wet washcloth under your armpit.
  • Take over-the-counter pain medicine.
  • Get plenty of rest.

There are other, less common but more serious causes of swollen lymph nodes, including a malignancy or lymphoma. See your doctor if yours:

  • Appear for no 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

Breast cancer happens when cells in your breast grow uncontrollably. They usually form a tumor.

A common symptom of breast cancer is pain and swelling around 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, so if things don’t feel right, be sure to see a doctor.

There are several treatments for breast cancer that has spread to your lymph nodes. The one you and your medical team will choose depends on the stage and type of cancer:

Surgery. During breast-conserving surgery (called a lumpectomy), doctors will remove the cancer and leave as much normal breast tissue as possible. They’ll also take out some lymph nodes and healthy tissue. When this type of surgery isn’t an option, doctors will remove your entire breast (mastectomy).

Radiation therapy. Doctors use high-energy rays or particles to destroy cancer cells, lower the chance of the cancer coming back, and help you live longer.

Chemotherapy and other drugs. Hormone therapy is used after surgery to lower the chance of your breast cancer coming back. For larger tumors, tumors that grow fast, or ones with certain features, your doctor may recommend anti-cancer drugs (chemotherapy).