Why do I get a sharp pain when I breathe deep?

Pain that stabs when you breathe in has a classic explanation: pleurisy, inflammation of the pleura - the two thin layers wrapping your lungs. Healthy layers slide silently over each other with every breath; inflamed ones rub, and the NHS describes the result exactly: sharp chest pain when you breathe in, often worse when you cough, sneeze, or move, sometimes spreading to the shoulders and back. The cause is usually a viral infection, and the NHS says it is easy to treat and usually gets better in a few days - rest and ordinary painkillers while it settles. MedlinePlus adds the fuller cause list: pneumonia and other infections, chest trauma, and - the one that makes this symptom deserve respect - a blood clot on the lung (pulmonary embolus). The dividing lines: pleurisy-type pain with a cough and mild fever after a cold is the common, calm version. Sharp breathing pain with sudden breathlessness, a fast heartbeat, coughing blood, faintness, or one swollen calf is the emergency version - that combination needs 911 or the ER, not an appointment. The NHS also says pleurisy can signal pneumonia, so pain with a high fever and feeling genuinely ill earns a same-day call to a GP or 111. Do not simply endure recurring sharp breathing pain for weeks - even the calm version deserves a listen from a doctor if it keeps returning. Pymander is a free AI doctor, 24/7 by text, that can help you size up the pattern.