A collapsed lung happens when air leaks into the space between your lung and your chest wall, putting pressure on the lung and preventing it from expanding fully. If the entire lung collapses, the condition is called a pneumothorax. If only a portion of the lung is affected, it’s called atelectasis. Either way, the result is the same: your lung can’t inflate properly, and your body gets less oxygen than it needs.
How a Lung Collapses
Your lungs sit inside your rib cage surrounded by a thin, fluid-filled space called the pleural space. Normally, this space has no air in it, and the slight vacuum it creates keeps your lungs inflated as you breathe. When air enters the pleural space, whether from a hole in the lung itself or a wound in the chest wall, that vacuum breaks. The lung on the affected side shrinks inward, partially or completely, depending on how much air leaks in.
Think of it like a balloon inside a sealed jar. If you poke a hole in the jar, outside air rushes in and the balloon deflates. In a collapsed lung, the “jar” is your chest cavity and the “balloon” is the lung tissue.
Types and Causes
Primary Spontaneous Pneumothorax
This type strikes people who have no known lung disease. It typically happens when a small air-filled blister on the lung surface, called a bleb, ruptures without warning. The classic profile is a tall, thin young male. Men are affected far more often than women, with an incidence of roughly 7 to 18 cases per 100,000 males per year compared to 1 to 6 per 100,000 females. Cigarette smoking significantly increases the risk.
Secondary Spontaneous Pneumothorax
This occurs in people who already have an underlying lung condition. The most common culprits are COPD, asthma, cystic fibrosis, and severe pneumonia. Tuberculosis and certain lung infections also weaken lung tissue enough to cause a collapse. Less frequently, lung cancer, pulmonary fibrosis, and sarcoidosis are responsible. Some connective tissue disorders, including Marfan syndrome and Ehlers-Danlos syndrome, make lung tissue more fragile and raise the risk as well.
Traumatic Pneumothorax
Any injury that punctures the chest wall or damages the lung can force air into the pleural space. Car accidents, stab wounds, broken ribs, and even certain medical procedures like central line placement or lung biopsies can trigger this type.
What It Feels Like
The hallmark symptom is a sudden, sharp pain on one side of the chest, often near the shoulder. The pain gets worse when you take a deep breath or cough. Shortness of breath comes on quickly and can range from mild to severe depending on how much of the lung is involved.
A small collapse might feel like a pulled muscle or a stitch in your side. A larger one produces more alarming symptoms: chest tightness, rapid heart rate, lightheadedness, extreme fatigue, and visible changes in breathing effort. In serious cases, the skin can turn bluish from lack of oxygen, a sign called cyanosis.
When It Becomes an Emergency
A tension pneumothorax is the most dangerous form. It works like a one-way valve: air enters the pleural space with each breath but can’t escape. Pressure builds rapidly, compressing not just the affected lung but eventually shifting the heart and major blood vessels, compressing the opposite lung, and cutting off blood flow back to the heart. This causes a sharp drop in blood pressure, visibly distended neck veins, and the windpipe shifting to one side. Without immediate treatment, it leads to shock and can be fatal within minutes. This is a true medical emergency.
How It’s Diagnosed
Doctors often suspect a collapsed lung based on physical examination alone. Listening with a stethoscope reveals decreased or absent breath sounds on the affected side, and tapping on the chest produces a hollow, drum-like sound instead of the normal dull tone.
A chest X-ray is the most common first test, but it catches only about 37% of pneumothoraces in trauma patients. Ultrasound performs significantly better, detecting roughly 83% of cases. CT scans are the gold standard and pick up even very small air collections that other imaging misses. In an emergency, doctors may skip imaging entirely and treat based on clinical signs.
Treatment Options
Treatment depends on the size of the collapse and how you’re feeling. A small pneumothorax that isn’t causing significant pain or breathing trouble can sometimes be managed conservatively, meaning you’re monitored closely while the air reabsorbs on its own over days to weeks. This approach works regardless of the pneumothorax size, as long as symptoms remain minimal.
When the collapse is larger or symptoms are more severe, two main interventions are used. Needle aspiration involves inserting a needle into the chest to manually withdraw the trapped air. It’s a quick procedure, often done at the bedside. If that’s not sufficient, a chest tube is placed between the ribs and connected to a drainage system that continuously pulls air out of the pleural space. The tube typically stays in for a few days until the leak seals and the lung re-expands.
For recurrent collapses or cases where air keeps leaking, surgery becomes the next step. A minimally invasive procedure uses a small camera and instruments inserted through tiny incisions to find and remove the ruptured blebs. To prevent future episodes, surgeons typically combine this with pleurodesis, a technique that intentionally irritates the pleural surfaces so they scar together, sealing the space where air would otherwise accumulate.
Recurrence Risk
One of the most important things to know about a collapsed lung is that it can happen again. After a first primary spontaneous pneumothorax, the recurrence rate ranges from 10 to 30% over one to five years, with some studies reporting pooled one-year recurrence rates as high as 29%. The highest risk period is the first 30 days through the first year.
One large study tracked recurrence rates in detail. For men, the chance of a repeat collapse was 4% within the first week, 10% within three months, 13% within a year, and 20% within five years. Women had similar numbers: 5% within a week, 11% within three months, 15% within one year, and 22% within five years. Pleurodesis during surgical repair substantially reduces these odds.
Recovery and Activity Restrictions
Recovery from a small, uncomplicated pneumothorax typically takes one to two weeks. If a chest tube was needed, expect to spend a few days in the hospital, with full recovery taking several weeks. Surgical recovery adds a bit more time, though the minimally invasive approach means most people return to normal activities within two to four weeks.
Air pressure changes pose a real concern after a collapsed lung. Scuba diving is widely considered off-limits for anyone with a history of spontaneous pneumothorax because the pressure changes of compressed-air diving stress lung tissue in exactly the ways that could trigger another collapse. Flying in commercial aircraft, which have lower cabin pressure than sea level, also carries some risk in the period shortly after a collapse. Your doctor will give you a specific timeline for when air travel is safe, usually after confirming the lung has fully re-expanded and healed.
Smoking cessation is one of the most effective steps you can take to reduce recurrence risk, since smoking is both a cause and an amplifier of the underlying lung tissue changes that lead to spontaneous collapse.