Stabbing pain when breathing, also described as "knife-like," is distressing. Pain caused by a condition in the lung is often sharp, and commonly worsens during a deep breath. A variety of disorders, some which are very serious, can cause stabbing pain when breathing. Disorders not involving the lungs may also cause a similar symptom. A physician should evaluate the cause of a the pain.
Membranes, or pleura, surround the lungs and line the chest cavity, separating them. Pleurisy results when inflammation develops between these two layers, the Mayo Clinic explains. Inflammation causes the layers to rub against each other, producing the characteristic sharp pain of pleurisy that occurs during breathing. An underlying medical condition, such as the flu, pneumonia or other infection, can cause pleurisy. Other causes include autoimmune diseases such as Lupus, injury to the chest, broken ribs, open heart surgery and tuberculosis. A collection of fluid between the inflamed layers, or pleural effusion, can occur, which stops the pain but can result in a collapsed lung. Treatment focuses on eliminating the underlying cause and relieving pain. If a large pleural effusion developed, it may need to be drained.
Pulmonary embolism, or PE, is a sudden blockage of an artery in the lungs by a blood clot that traveled from somewhere else in the body, most commonly the legs. A blood clot that forms in a vein and then breaks off and travels through the circulation is called an embolus, the National Heart, Lung and Blood Institute explains. A PE is a life-threatening condition. It can cause low oxygen levels in the blood which can damage organs, permanently damage part of a lung and cause death if multiple clots, or a large clot, causes the problem. Symptoms include a sharp, stabbing pain in the chest during breathing, shortness of breath and a rapid heart rate.
A pneumothorax is an accumulation of air into the pleural space, or the space between the lung and chest cavity, that results in a collapsed lung. The collapse can be partial or complete, and results when injury or disease, such as emphysema, causes a hole in the pleural space, which then fills with air. A spontaneous pneumothorax can also occur, and has no known cause. Symptoms depend on the extent of the collapse, and include shortness of breath, a stabbing pain when breathing, pain in the shoulder or abdomen and a dry, hacking cough. Shock, cardiac arrest and death can result, says the National Heart, Lung and Blood Institute.