Pleurisy develops when the thin, two-layered membrane surrounding your lungs becomes inflamed. The most common cause is a viral infection like the flu, but it can also result from bacterial infections, autoimmune diseases, chest injuries, blood clots, and long-term environmental exposures. Understanding the specific triggers helps explain why this condition can show up in otherwise healthy people and in those with chronic illness alike.
What Happens Inside Your Chest
Your lungs are wrapped in a double-layered membrane called the pleura. Normally, these two layers glide smoothly against each other as you breathe. When one or both layers become inflamed, their surfaces roughen and start catching against each other with every breath. This friction is what produces the hallmark pain of pleurisy: a sudden, sharp, stabbing or burning sensation that gets worse when you inhale deeply, cough, sneeze, or laugh.
The outer layer of the membrane is the one that actually generates pain. It’s wired with sensory nerves that respond to trauma or inflammation. When inflammatory chemicals flood the space between the two layers, they activate those local pain receptors. Depending on where the inflammation sits, you may feel it in your chest wall or, if the central part of the diaphragm is involved, the pain can travel up to your neck or shoulder on the same side.
Viral and Bacterial Infections
Infections are the single most common route to pleurisy. A viral illness, particularly influenza, can inflame the pleural membrane directly. This type of pleurisy often follows a few days of typical flu symptoms and tends to resolve on its own as the virus clears, though the chest pain can linger for a week or more.
Bacterial pneumonia is the other major infectious cause. When bacteria infect the lung tissue, the inflammation can spread outward to the pleura. In more serious cases, infected fluid collects between the pleural layers, a condition called empyema, which requires drainage. Tuberculosis is another bacterial infection historically linked to pleurisy, particularly in parts of the world where TB remains common.
Autoimmune Diseases
Your immune system can also turn against the pleura. Lupus is one of the most well-known triggers. About 50% of people with lupus experience some form of lung involvement over the course of their disease, and pleurisy is among the most frequent complications. The inflammation happens because the immune system mistakenly attacks the body’s own pleural tissue, producing the same roughening and pain as an infection would.
Rheumatoid arthritis is another autoimmune condition that can cause pleurisy, sometimes even before joint symptoms become obvious. In these cases, pleurisy tends to come and go in flares that mirror the underlying disease activity. Treating the autoimmune condition itself is typically what brings the pleural inflammation under control.
Blood Clots in the Lungs
A pulmonary embolism, where a blood clot travels to the lungs, is a serious and sometimes overlooked cause of pleuritic chest pain. The clot blocks blood flow to a section of lung tissue, and the resulting damage and inflammation irritates the nearby pleura. The pain feels similar to other forms of pleurisy, but it often comes on very suddenly and may be accompanied by shortness of breath, a rapid heartbeat, or coughing up blood. This is a medical emergency, and the pleuritic pain is sometimes the first sign that a clot has reached the lungs.
Chest Injuries and Rib Fractures
Physical trauma to the chest can directly irritate or damage the pleura. A broken rib is the most straightforward example. If a fractured rib displaces far enough, bone fragments can actually penetrate into the pleural space, introducing bacteria and setting off an infection. Even without a full break, a hard blow to the chest from a car accident, a fall, or a sports injury can bruise the pleural layers enough to cause inflammation. Chest surgery is another common trigger, as the procedure itself disrupts the pleural membrane and the healing process involves a period of local inflammation.
Medications
Certain prescription drugs can cause pleural inflammation as a side effect. One well-documented example is nitrofurantoin, an antibiotic commonly prescribed for urinary tract infections. The reaction typically begins 2 to 10 days after starting the drug. Fever and cough develop in most cases, and pleurisy occurs in roughly one-third of affected patients. This reaction is not dose-dependent, meaning it can happen at standard doses. Other medications linked to pleural irritation include some heart rhythm drugs and blood pressure medications. If pleurisy develops shortly after starting a new prescription, the timing is worth mentioning to your doctor.
Asbestos and Occupational Exposure
Long-term exposure to asbestos is a well-established cause of several pleural diseases, including non-cancerous inflammation and thickening. Pleural plaques, which are patches of scarred tissue on the pleura, appear in more than 50% of workers who were directly exposed to asbestos. These changes don’t always cause symptoms, but they signal that the pleura has been damaged.
What makes asbestos-related pleural disease unusual is its timeline. Most forms require at least 10 years of exposure to develop, even at low intensity. Pleural plaques typically take 20 to 30 years to appear. Diffuse pleural thickening, a more widespread form of damage, averages 34 years from the onset of exposure. The one exception is non-cancerous asbestos pleural effusion, where fluid collects around the lungs, which can develop in under 10 years. People who lived with asbestos workers or near industrial sites can also be affected, though at lower rates than those with direct occupational exposure.
Other Causes
Certain cancers, particularly lung cancer and mesothelioma, can cause pleurisy when tumors grow into or near the pleural lining. Lymphoma and cancers that have spread to the chest from other parts of the body can do the same. Kidney failure and liver disease sometimes lead to fluid buildup around the lungs that irritates the pleura. Even something as common as a viral upper respiratory infection in an otherwise healthy person can occasionally trigger a brief episode of pleurisy that resolves without specific treatment.
How Pleurisy Is Identified
The pain itself is often the biggest clue. The sharp, breath-dependent quality of pleuritic chest pain is distinctive enough that it points doctors toward the pleura rather than the heart or muscles. During a physical exam, a doctor may hear a “pleural friction rub” through a stethoscope, a grating or creaking sound produced by the roughened pleural surfaces rubbing together as you breathe. Chest X-rays, CT scans, and blood tests help pin down the underlying cause, whether that’s an infection, a clot, or an autoimmune flare. Treatment depends entirely on what triggered the inflammation in the first place, since pleurisy is always a symptom of something else happening in the body.