Pain In or Under Left Breast: Causes and When to Get Help

Experiencing pain under your left breast can be concerning and leave you wondering what might be causing it. There are several potential reasons for this discomfort, ranging from mild muscle issues to more serious heart-related concerns. 

Certainly, one possible source of this pain is muscle soreness, particularly after an intense workout or engaging in activities that strain the chest and surrounding muscles. 

What’s Causing This Pain Under My Left Breast

Heart, chest, digestive system conditions, infections, and hormonal fluctuations are, however, also among potential causes of pain under the left breast. Identifying the underlying cause and seeking appropriate treatment are essential for addressing and managing this discomfort effectively.

Causes: Heart and Chest

Pain under the left breast can sometimes signal issues related to the heart or other structures in the chest. While some causes may be relatively benign, such as indigestion, others can potentially involve serious cardiovascular conditions.

Causes - Heart and Chest

Heart Conditions

Angina is a possible cause of pain under your left breast. When the heart muscle doesn’t receive enough oxygen through the coronary artery, it can cause chest pain. 

Heart attacks can cause similar symptoms, including chest pain, shortness of breath, and nausea. It’s always important to seek medical attention if you suspect a heart attack.

Heart Conditions

Pericarditis, the inflammation of the pericardium surrounding the heart, might also cause pain under the left breast. 

This sharp chest pain occurs when the irritated layers of the pericardium rub against each other. Mild cases often resolve without treatment.


Pleurisy, inflammation of the tissue lining the lungs and chest cavity, can cause sharp, stabbing pain that worsens with deep breaths, coughing, or sneezing. The pain may radiate to your shoulders or arms. 


Treatment usually targets the underlying cause, which could be a viral infection, pneumonia, or other illness.


Costochondritis is an inflammation of the cartilage connecting the ribs to the breastbone. It can cause pain under the left breast, which may feel like a deep ache or sharp stabbing sensation. The pain may worsen with movement, coughing, or deep breathing. Treatment often involves pain relievers, such as NSAIDs, and rest.


Causes: Digestive Issues

Digestive issues are a common cause of pain under your left breast. While the digestive system may seem far from the chest, conditions affecting the stomach, esophagus, or even the colon can present as chest discomfort.


This common digestive issue occurs when stomach acid travels up the esophagus and causes burning pain right behind the breastbone, which can also be felt under the left breast. 


Occasional heartburn is often manageable with over-the-counter medications and lifestyle changes. However, if heartburn is frequent or interferes with daily life, it might indicate a more serious condition like GERD and should be evaluated by a healthcare provider.

Gastroesophageal Reflux

Gastroesophageal reflux disease (GERD) is a more severe form of heartburn, often accompanied by bloating and abdominal pain. Over-the-counter antacids can help manage GERD symptoms.

Gastroesophageal Reflux

While GERD is not usually a serious condition, chronic acid reflux can cause significant discomfort and potential complications like esophagitis. It’s important to manage GERD symptoms with lifestyle modifications and possibly medications, guided by a healthcare professional.

Hiatal Hernias

Hiatal hernias, caused by a part of the stomach bulge pushing through the large muscle and separating the abdomen and diaphragm, can lead to similar pain. Increased pressure on the stomach during pregnancy may contribute to this condition.

Hiatal Hernias

Smaller hiatal hernias often cause no signs or symptoms, but larger ones can cause chest pain, belching and discomfort. Treatment depends on the severity and might range from lifestyle changes to surgery.


These small and hard deposits that form in the gallbladder can block bile ducts and cause pain in the left breast area. This pain may radiate to the back or shoulder, accompanied by sweating. 

The pain typically happens after meals and can be severe.


Gallstones often require medical treatment, such as medication to dissolve the stones or surgery to remove the gallbladder, so be sure to consult a doctor if you experience these symptoms.


Pancreatitis is a swelling of the pancreas, sometimes resulting from long-term ibuprofen use, high triglycerides, or heavy alcohol consumption. Symptoms may include pain under the left breast, fever, and vomiting.


The pain often occurs shortly after a meal and can become severe, lasting for several hours to a few days. The condition often requires hospitalization for treatment, which includes fasting, pain medication, and intravenous fluids.

Other Causes

Less common causes of digestive pain include colon cancer, bacterial infection, and ulcerative colitis. It is essential to consult a healthcare professional to diagnose and treat any underlying illnesses. 

colon cancer

Causes: Other

Several other factors may contribute to pain under the left breast. These can range from psychological factors, such as anxiety, to various physiological conditions, such as infections, hormonal changes, or even physical activity.

Anxiety and Stress

Anxiety can sometimes cause physical symptoms, including chest pain. While it may not be the first cause to consider for pain under the left breast, for those with generalized anxiety disorder or panic attacks, chest pain is a common symptom. 

Anxiety and Stress

Stress can also trigger this discomfort. While chest pain related to anxiety is often distinct from that of a heart issue, it may mimic cardiac-related pain.

Consult a healthcare provider if you experience this symptom to rule out serious conditions.

Respiratory Infections

Infections, particularly those related to the respiratory system, like pneumonia, can cause pain under the left breast. The discomfort usually worsens with deep breathing or coughing and is often accompanied by other symptoms like fever, cough, and fatigue.

Respiratory Infections

While some infections can resolve on their own, others, especially those that cause severe chest pain or discomfort, should be evaluated by a healthcare provider. Specific medical treatments may be needed depending on the infection.


The spleen, located under your left rib cage, ideally should not cause pain under normal conditions. However, certain circumstances, such as an enlarged spleen (splenomegaly), a ruptured spleen, physical injury, stress, or an infection, can cause discomfort or pain under the left breast.


Any spleen-related pain warrants immediate medical attention as it can potentially be a medical emergency. An injured or ruptured spleen can cause internal bleeding that needs urgent care. If you suspect your spleen is the source of your pain, seek immediate medical help.

Hormones and Physical Activity

In young adults, hormonal fluctuations can lead to chest pain or discomfort under the left breast, especially in females during menstruation or pregnancy, which can be amplified by stress or anxiety. 

Hormones and Physical Activity

Mild muscle strain caused by strenuous physical activity or exercise can also contribute to discomfort in the same area. Home remedies and relaxation techniques can offer relief, but if pain persists or worsens, consult your doctor.

While these causes are generally less alarming, if the pain is persistent, severe, or accompanied by other concerns like difficulty breathing or palpitations, it is advisable to remain vigilant in the observation and seek medical attention when the pain intensity increases. 

Mild muscle strain

Always listen to your body and report anything unusual or concerning to your healthcare provider.

When to See a Doctor

If you experience pain under your left breast, monitor your symptoms closely. 

Chest pain, especially when accompanied by shortness of breath, nausea, vomiting, or dizziness, as well as pain radiating to the arm or jaw or severe pressure in the chest, may indicate a heart-related issue. Do not hesitate to seek medical attention if these symptoms arise.

shortness of breath

Besides chest pain, swelling and a feeling of impending doom should also prompt you to consult a healthcare provider. These could be signs of a potentially serious illness.

Pay attention to changes in pain when coughing, sneezing, or taking a deep breath. This type of discomfort can give more insight into the underlying cause.

Pay attention to changes in pain

Equally important, if you experience sudden sweating or lightheadedness, it’s crucial to contact a healthcare professional. Persistent or recurrent chest pain, regardless of its nature, should always be evaluated to rule out any severe health issues.

Frequently Asked Questions

What causes dull pain under the left breast?

Dull pain under the left breast can be caused by several factors, including muscle soreness, and heart issues like angina.

What causes dull pain under the left breast

Pain may also be related to costochondritis – an inflammation of the cartilage connecting the rib to the breastbone.

Why does sharp pain occur under the left breast while lying down?

Sharp pain under the left breast while lying down could be due to heart-related issues like angina, lung problems, injuries, or even position-related changes. 

Why does sharp pain occur under the left breast while lying down

It’s essential to consult a healthcare professional if this pain persists.

Why does pain occur under the left breast after eating?

Pain under the left breast after eating can be associated with gastrointestinal issues such as indigestion, heartburn, or trapped gas. 

Why does pain occur under the left breast after eating

However, if the pain consistently occurs after eating, it’s best to reach out to a healthcare professional for further evaluation.