What might cause left side chest pain when breathing?

When you take a deep breath and feel pain on the left side of your chest, there are several possible reasons. One possibility is that the lining around your lungs, called the pleura, is inflamed. This condition, known as pleurisy, can cause sharp pain when you breathe in deeply. Other problems, like pneumonia or a blood clot in the lungs, may also cause chest pain with breathing.

Heart-related issues, like an acute myocardial infarction (a heart attack), can also present with left-sided chest pain, although the pain associated with heart problems might be accompanied by other symptoms such as sweating, nausea, or shortness of breath. Additionally, the pain could come from the muscles or cartilage in the chest wall—this is often a musculoskeletal problem like costochondritis, where the cartilage connecting the ribs becomes tender and painful, especially when you breathe.

Because these potential causes range from less serious to serious, it is important to seek medical attention if the pain is new, severe, or comes with other concerning symptoms. To help identify what might be causing your chest pain, you can start by taking a free AI symptom checker before consulting with your doctor to determine the underlying cause and recommend the proper treatment.