What causes pain under my left breast? Related conditions and treatments

Overview: What does pain under my left breast feel like?

Pain under the left breast can occur for many different reasons. These can include heart-related problems, injuries, and hormonal changes. Sometimes, you may feel sudden, sharp, or stabbing pain. In other cases, it can be dull or achy. While many causes of pain under my left breast are benign, some can be life-threatening and require immediate medical attention. 

Read on to learn more about the most common causes of pain under the left breast.

What causes pain under my left breast?

There are many possible causes of pain under the left breast. It can be due to something benign, such as heartburn. Or it can be a sign of a medical emergency, such as a heart attack. 

Let’s explore some common causes of pain under the left breast. 

Heart-related causes

1. Heart attack

A heart attack occurs when a coronary artery, which supplies the heart with blood, is suddenly blocked. Heart attacks are a medical emergency that requires prompt treatment. And because the heart is located slightly to the left of the midline of the chest, pain under the left breast may be a sign of a heart attack. 

Other symptoms of a heart attack can include: 

• Chest pain, pressure, or discomfort

• Pain that spreads from the chest or arms to the neck, jack, or back

• Heartburn 

• Stomach pain

• Shortness of breath

• Cold sweats

If someone develops these symptoms, call 911 or the local emergency number right away. 

2. Angina

Chest pain caused by poor blood flow to the heart is called angina. It can feel like pressure or squeezing in the chest or under the left breast. This pain can also occur in the shoulders, arms, neck, jaw, stomach, or back. 

But angina isn’t a disease. It’s typically a symptom of a larger medical problem, such as heart disease. 

3. Pericarditis

The pericardium is a thin, sac-like structure that surrounds the heart. Pericarditis occurs when the pericardium becomes inflamed because of a possible infection, injury, or medical condition. One of the most common symptoms is pain in the upper left side or middle of the stomach or under the left breast.

Breast-related causes

1. Injury

The breast is covered with sensitive skin. An injury to the left breast can also cause pain under the left breast. The pain may also be accompanied by brushing, aching, and tenderness. Typically, breast injuries will resolve on their own over time. If the pain is substantial, discuss treatment options with your healthcare provider. They may recommend an over-the-counter (OTC) pain relief medication, such as Tylenol (acetaminophen) or Advil (ibuprofen). 

2. Breast surgery

Any kind of breast surgery, such as a mastectomy, breast augmentation, or breast reduction, can be a cause of pain under the left breast. You can have sharp pain or feel like a cramping or burning sensation. Similar to an injury, pain will likely be at its worst immediately after surgery and improve as the breasts and incision heal. 

3. Milk duct problems

Pain under the left breast causes may also include conditions that develop in the milk ducts. Examples of these conditions include:

• Clogged milk duct: Women who breastfeed can develop clogged milk ducts, which can cause firm, tender lumps in the breast that result in pain in or under the breast. 

• Mastitis: Mastitis is an infection of the breast tissue. It’s commonly the result of a clogged milk duct and can cause symptoms such as breast tenderness or pain, swelling in the breast, and fever. 

• Fibroadenoma: Fibroadenomas are benign growths in the breast that may cause aches and pain. 

• Duct ectasia: Duct ectasia is when a milk duct widens and fills with fluid. The duct may become clogged, which can result in breast pain, tenderness, or nipple discharge. 

4. Hormonal changes

Women often feel pain in or under the breasts during periods of hormonal changes. These changes may happen during certain periods of the menstrual cycle and pregnancy or while using infertility treatments, certain birth control medications, or hormone replacement therapy. 

5. Breast cancer 

Although rare, a cause of pain under the left breast includes breast cancer. Breast cancer is slightly more common on the left side of the body compared to the right. However, most breast cancers don’t cause pain in the breast or nipple. Nevertheless, if you are having persistent pain in or under the left breast, consult with a healthcare professional to be checked for breast cancer. 

Digestive causes

1. Heartburn

Heartburn is characterized by burning pain or discomfort in the chest, neck, or throat. It occurs when excess stomach acid moves up from the stomach into the esophagus, a tube connecting the throat to the stomach. Although heartburn has nothing to do with the heart, heartburn pain may be felt under the left breast because of where the esophagus is located.

2. Gastritis

Gastritis occurs when the lining of the stomach becomes inflamed and can cause burning, aching, and pain in the stomach. Because the stomach is located in the upper left region of the body, gastritis can also cause pain under the left breast.

3. Pancreatitis

The pancreas is an organ located behind the stomach in the upper region of the body. Pancreatitis occurs when the pancreas is inflamed, which happens when digestive enzymes activate inside the pancreas and digest the tissue of the pancreas. A major symptom of pancreatitis is pain in the upper left side or middle of the stomach or under the left breast.

Other causes

1. Costochondritis

The ribs are connected to the breastbone by cartilage. When there is inflammation of the cartilage, it’s called costochondritis. Costochondritis occurs more commonly on the upper left side of the body. So, it is a potential cause of pain under the left breast. 

2. Pleurisy

Pleurisy is inflammation of the lining of the lungs. It can cause sharp chest pain, which may feel like pain under the left breast. The pain can feel worse while breathing or coughing. 

3. Hiatal hernia

A hiatal hernia is when the top portion of the stomach pushes up into the chest cavity. Because the stomach is located in the upper left region of the body, the pain from a hiatal hernia may be felt under the left breast. 

Should I be worried about pain under my left breast?

Causes of pain under the left breast are typically benign, such as an injury, costochondritis, or heartburn. However, there are some cases where pain under the left breast can be a sign of a life-threatening condition, such as a heart attack or breast cancer. Because of this, it’s best to consult a healthcare provider if you have pain under the left breast, especially if there is a lump or skin is dimpling on the breast. And if the pain is sharp, sudden, radiates to your neck or jaw, or is accompanied by shortness of breath, call 911 to seek emergency medical help right away. If the pain is related to a heart attack, it requires prompt medical treatment to prevent heart damage or even death. 

How is the cause of pain under my left breast diagnosed?

It’s recommended to talk with a healthcare provider if you experience pain under the left breast. They can ask questions to determine the cause of the pain, such as when it started, what makes it worse or better, and if you’ve been injured recently. They may also order tests, such as an X-ray or mammogram. 

How long does pain under my left breast last?

The time it takes for pain under the left breast to disappear depends on the cause. If heartburn is the cause, the pain may last a few hours after a meal or go away once some dietary changes are made, such as limiting spicy foods. If the cause of pain is an injury, it can take weeks for the pain to go away as you heal. Some causes of pain under the left breast will only resolve with treatment. For example, if the pain is related to a heart attack, it will likely continue until a healthcare provider treats you. 

How to stop pain under my left breast

Pain under the left breast treatment depends on the specific cause. Most causes of pain under the left breast cannot be treated at home and need medical care. For example, pain caused by heartburn or a hiatal hernia is treated with drugs that reduce acid reflux, such as proton pump inhibitors (PPIs) and antacids. Some antacids and PPIs are available over the counter, but if you’re unsure if the pain is related to those issues, they won’t help. If the pain is caused by an injury, costochondritis, or surgery, pain relievers can help. Otherwise, you may need time to heal. In the rare case that the pain is caused by breast cancer, treatment will depend on the severity of the condition. 

What’s next? Additional resources for people with pain under my left breast

Test and diagnostics

• Breast pain, Mayo Clinic 

Treatments

• Left-side chest pain, Cleveland Clinic

Scientific studies and clinical trials

• Persistent postmastectomy pain in breast cancer survivors: Analysis of clinical, demographic, and psychosocial factors, The Journal of Pain