Pain localized to the left submammary or subcostal region often causes significant concern due to its anatomical proximity to the heart. This area of the chest is a complex intersection of multiple body systems, including the cardiovascular, respiratory, musculoskeletal, and gastrointestinal tracts. Pain originating here can stem from a wide array of sources, ranging from temporary muscle strain to serious, life-threatening conditions. Understanding the characteristics of the discomfort—such as whether it is sharp, dull, or positional—is important in determining its potential origin. This article provides general information regarding possible causes and is not a substitute for professional medical diagnosis or treatment.
Cardiac and Major Organ Causes
Pain under the left breast is frequently associated with the heart, making cardiac conditions a primary concern. Reduced blood flow to the heart muscle (myocardial ischemia) can manifest as angina, often described as squeezing, pressure, or fullness beneath the breastbone that may radiate to the left arm, jaw, or back. This discomfort typically worsens with physical exertion and subsides with rest. A heart attack (myocardial infarction) occurs when blockage is severe, resulting in crushing chest pressure that lasts more than a few minutes, frequently accompanied by cold sweats, nausea, or shortness of breath.
Inflammation of the tissues surrounding the heart can also cause intense pain. Pericarditis, inflammation of the pericardium (the sac encasing the heart), causes a sharp, stabbing sensation. This pain often changes with body position, typically worsening when lying flat and easing when sitting up and leaning forward. A severe cause is an aortic dissection, a tear in the inner layer of the aorta, presenting as sudden, severe tearing or ripping pain in the chest or back.
Nearby major organ systems, specifically the lungs, can also refer pain to the left subcostal area. Pleurisy, inflammation of the lining of the lungs, causes a sharp pain distinctly aggravated by deep breathing, coughing, or sneezing. Furthermore, conditions involving organs like the spleen or pancreas may present as referred pain higher up in the chest. Pancreatitis, for example, can cause abdominal pain that radiates upward, occasionally being felt near or under the left breast.
Musculoskeletal and Chest Wall Pain
Most instances of pain felt under the left breast originate not from internal organs but from the structures of the chest wall, including bone, cartilage, and muscle. The most common cause is costochondritis, an inflammation of the cartilage connecting the ribs to the breastbone. This condition typically causes a localized, sharp pain that is tender to the touch at specific points along the ribs, often worsening with deep breaths or movement.
A related condition is Tietze syndrome, which is similar to costochondritis but is usually accompanied by noticeable swelling over the affected cartilage, typically involving the upper ribs closer to the shoulder. Muscle strains, particularly involving the intercostal muscles between the ribs or the pectoral muscles, are also frequent culprits. These strains cause a dull or sharp ache aggravated by twisting, lifting, or vigorous exercise, and often improve with rest.
Nerve-related issues can also produce localized pain. The viral infection herpes zoster (shingles) can cause intense, burning, or shooting pain in the area supplied by an affected nerve root before any rash appears. This pre-eruptive phase can be mistaken for other forms of chest pain, sometimes presenting as localized discomfort under the breast. Another benign source of sharp, momentary pain is Precordial Catch Syndrome, involving a brief, sudden, stabbing sensation that resolves quickly and is related to irritation of the chest wall nerves.
Gastrointestinal and Referred Pain
The digestive system is a frequent source of pain that mimics cardiac or musculoskeletal discomfort due to the phenomenon of referred pain. The esophagus and the stomach, positioned slightly to the left, are close enough to cause symptoms in the sub-breast region. Gastroesophageal Reflux Disease (GERD), or acid reflux, occurs when stomach acid flows back into the esophagus, producing heartburn that can be felt in the chest. This burning sensation is often mistaken for a heart issue, especially if it occurs after eating a large meal or when lying down.
Gastritis, inflammation of the stomach lining, can also lead to pain in the upper left abdomen that is sometimes perceived under the breast. Peptic ulcers, open sores in the stomach or small intestine lining, cause a gnawing or burning pain that may be referred to the chest area, often relieved temporarily by eating or taking antacids.
A hiatal hernia, where a portion of the stomach pushes up through the diaphragm, can also trigger symptoms in this area. This displacement exacerbates acid reflux, causing burning and pressure felt below the left breast. Simple issues like trapped gas or functional dyspepsia (indigestion) can also cause significant, temporary pressure and discomfort that is misinterpreted as a more serious chest problem.
Identifying Urgent Symptoms and Seeking Care
While many causes of pain under the left breast are minor, recognizing warning signs associated with serious conditions is important for prompt action. Immediate emergency medical attention is necessary if the pain is described as sudden, severe crushing or squeezing pressure that does not abate. This is particularly urgent if the pain radiates to the jaw, neck, back, or down one or both arms.
Other serious symptoms requiring an immediate call to emergency services include:
- Feeling dizzy, lightheaded, or faint.
- Experiencing sudden shortness of breath.
- Breaking out in a cold sweat alongside the pain.
- Sharp and severe pain accompanied by a feeling of tearing or ripping (signaling an aortic emergency).
For persistent, non-emergent pain that comes and goes, such as discomfort related to movement or eating, a consultation with a primary care physician is the appropriate next step. They can conduct a thorough evaluation to accurately diagnose the source of the discomfort.