There are several causes of pain in the breast and armpit. Some of the most common causes include hormonal changes, an ill-fitting bra, or a muscle strain.

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We all experience aches and pains from time to time. One type of pain you may encounter is breast pain that spreads to, or includes, your armpit.

There are several causes for this type of pain. However, when it happens, it can sometimes be hard to determine what causes it and whether it’s serious.

In this article, we’ll look at the possible causes of breast and armpit pain, the symptoms that are typically associated with these causes, and when it’s important to contact a doctor.

There are many different causes of breast pain. Sometimes, pain may also occur around the armpit.

It’s important to point out that this type of pain doesn’t just affect women. Breast and armpit pain can affect people of all genders.

That said, people assigned female at birth can experience two different types of breast pain. These are cyclic and noncyclic breast pain.

Cyclic breast pain

Cyclic breast pain is associated with your menstrual cycle. It involves swelling and tenderness that often affects both breasts and can spread to the underarm area as well.

This type of breast pain typically comes on about a week before your period and then eases during the course of your menstrual cycle. Most breast pain in people assigned female at birth tends to be cyclic.

Noncyclic breast pain

Noncyclic breast pain does not follow the pattern of your menstrual cycle and can come on at any time.

Instead of the generalized pain felt with cyclic breast pain, noncyclic breast pain is typically sharper and affects a specific area.

Below, we’ll explore the different causes of breast and armpit pain. For each cause, we’ll also call attention to any additional symptoms to be aware of and the possible treatment options.

Changes in a person’s hormones can cause breast pain that spreads to the armpit. Some examples of when this may occur include:

Breast and armpit pain due to hormonal changes is typically dull, achy, and impacts both sides of the body. The breasts may also feel tender and swollen.

There are ways to help ease this type of pain, such as:

At a minimum, a bra that doesn’t fit well can be uncomfortable or irritating. However, wearing a bra that doesn’t fit properly can also cause breast and armpit pain.

This problem is not uncommon. In fact, some research has found that about 80 percent of women wear an incorrectly sized bra. According to this research, around 70 percent wear bras that are too small, and 10 percent wear a bra that’s too large.

In order to find a bra that fits you well, consider having a professional bra fitting. To do this, look for a retailer that offers bra fitting services, focusing on those that specialize in lingerie.

A 2011 study illustrates the benefit of professional bra fittings by comparing professional bra fitting criteria with traditional bra fitting criteria in the United Kingdom. The traditional bra fitting criteria was found to be inaccurate, particularly for people with large breasts.

Mastitis is when breast tissue becomes inflamed or swollen. It most often occurs in breastfeeding people due to a buildup of milk or a bacterial infection.

One of the symptoms of mastitis is pain in the affected breast. Depending on the location, this may also spread to the armpit. Other symptoms of mastitis include:

  • swelling or redness of the affected breast
  • breast skin that feels hot to the touch
  • a firm or hard area in the affected breast
  • a painful or burning sensation when breastfeeding

If mastitis is due to a bacterial infection, you may also have additional symptoms like:

Mastitis can be treated by:

  • using OTC medications like acetaminophen and ibuprofen to ease pain and swelling
  • applying a warm compress to the affected area
  • drinking plenty of fluids
  • taking a course of antibiotics if a bacterial infection is present

If you’re breastfeeding, you can continue to breastfeed as you recover. In fact, breastfeeding and expressing milk from the affected breast may help speed up recovery.

It’s also possible that some types of muscle strain may be felt in the area of the breast and armpit. This includes strains to the muscles of your:

  • chest
  • neck
  • shoulders
  • back

If you’re having breast and armpit pain due to a muscle strain, you’ll likely experience a dull, aching pain on the side of your body where you experienced the injury. This pain may become worse when you move your arm, shoulder, or torso.

You can use OTC pain medications to alleviate pain and swelling due to muscle strains. Additionally, using the RICE method can also help treat muscle strains. This involves:

  • Rest. Try to rest the injured area, avoiding any motions or activities that may cause further irritation.
  • Ice. Apply an ice pack to the affected area several times each day for about 20 minutes at a time. Wrap the ice pack in a towel or cloth. Avoid applying the ice pack directly to your skin.
  • Compression. Wrap a bandage around the injured area to provide support.
  • Elevation. If possible, try to keep the painful area elevated as much as you can.

Lymph nodes are a key part of your lymphatic system. These small, bean-shaped glands help filter waste materials and harmful germs from your body’s tissues. They also carry immune cells that help fight disease and infection. Lymph nodes are found throughout your body, including in your armpits.

Typically, lymph nodes swell in response to an infection, such as mastitis or mono. In rarer cases, they can swell due to cancer or autoimmune disease. When lymph nodes in the armpit swell, it’s called axillary lymphadenopathy.

A swollen lymph node in the armpit will appear visibly enlarged and may be tender or painful, particularly when you touch it. If an infection is the cause, you may also have symptoms like fever, chills, or fatigue.

Swollen lymph nodes can be treated by addressing the condition that’s causing them. You can help ease any pain by using OTC medications or applying a warm compress to the affected area.

Breast cysts are fluid-filled sacs that can develop in your breasts. They’re typically round or oval in shape and may feel like a breast lump. According to, it’s estimated that about 25 percent of all breast lumps turn out to be cysts.

A breast cyst may cause pain or tenderness in or around the breast. This is particularly true just before you get your period.

Breast cysts may also be accompanied by fibrosis, which is when surrounding breast tissue becomes thickened and firm. This is known as fibrocystic changes.

Most cysts are benign and don’t require treatment unless they’ve become large or painful. In this situation, your doctor may recommend that the cyst be drained using a thin needle. This is called aspiration.

Mild pain from breast cysts can be addressed using various home remedies, such as:

  • taking OTC pain medications
  • applying a warm compress to the affected area
  • wearing a comfortable, supportive bra

One of the main concerns people have around breast and armpit pain is that it could be a sign of breast cancer.

While this could be a possibility, it’s unlikely to be a sign of breast cancer when the pain occurs by itself without other symptoms.

Some of the most common symptoms of breast cancer include:

If breast cancer is diagnosed, it can be treated in several ways, depending on the specific type and stage of the cancer.

Your care team will work with you to develop an appropriate treatment plan. Potential treatment options include:

If you have pain in your left breast and armpit, it’s possible that it could be a symptom of angina.

Angina is pain that happens when your heart doesn’t get enough blood. While it’s often felt in the chest, it can also affect other areas, such as your:

  • neck
  • shoulders
  • back
  • arms
  • abdomen

Angina pain can feel like tightness, squeezing, or burning. It may also happen in certain situations, such as after physical exertion or when you’re feeling stressed. Other symptoms of angina include:

Angina can be treated with medications, including but not limited to beta-blockers or calcium channel blockers. Your doctor will also recommend lifestyle changes like eating a heart-healthy diet, getting regular exercise, and reducing stress.

There are instances when it’s important to seek medical care for breast and armpit pain. Be sure to get medical attention if you have breast and armpit pain that:

  • is persistent or doesn’t go away with self-care
  • gets noticeably worse, either in the short- or long-term
  • doesn’t get better with OTC medications
  • happens with any of the following symptoms:
    • a hard lump that can be felt in the area of the breast or armpit
    • changes to the skin of the breast, such as dimpling or redness
    • unexplained nipple discharge
    • fever and chills
    • shortness of breath

There are several causes of pain in the breast and armpit. Some of the most common causes include hormonal changes, an ill-fitting bra, or a muscle strain.

Most of the time, breast and armpit pain isn’t serious. You can take steps to treat it at home by taking OTC medications, applying a warm compress, and wearing a supportive bra.

There are some instances when breast and armpit pain is a sign of a more serious condition.

See your doctor if your breast and armpit pain persists or gets worse, is associated with a noticeable bump or lump, or happens with symptoms like fever and chills.