A collapsed lung, known medically as a pneumothorax, almost always announces itself with two hallmark symptoms: sudden, sharp chest pain and shortness of breath. These symptoms typically appear without warning, even at rest, and can range from mild discomfort to a medical emergency depending on how much of the lung has deflated. Knowing the specific pattern of symptoms helps you distinguish a collapsed lung from other causes of chest pain and decide how urgently you need care.
The Two Main Symptoms
The signature of a collapsed lung is chest pain that strikes suddenly on one side. It tends to feel sharp or stabbing rather than dull or squeezing, and it gets noticeably worse when you breathe in deeply, cough, or move your upper body. This is called pleuritic pain, meaning it’s directly tied to the motion of breathing. Many people describe feeling like something “popped” or tore inside their chest just before the pain started.
Shortness of breath accompanies the pain in most cases. Even if the collapse is small, you may feel like you can’t get a full breath or that your breathing is shallow and unsatisfying. With a larger collapse, you might feel winded just sitting still. The combination of one-sided sharp chest pain plus sudden difficulty breathing is the clearest signal that air may have leaked into the space around your lung.
How It Feels Different From a Heart Attack
Because both conditions cause sudden chest pain, it’s natural to wonder whether you’re having a heart attack. A few key differences stand out. Heart attack pain is usually a pressure, tightness, or squeezing sensation in the center or left side of the chest, and it often radiates to the jaw, arm, or back. Collapsed lung pain is sharper, more localized to one side, and directly linked to breathing. Taking a deep breath makes pneumothorax pain spike; heart attack pain typically doesn’t change much with breathing.
That said, these patterns aren’t foolproof. Any sudden, severe chest pain with breathing difficulty warrants emergency evaluation, regardless of what you think the cause might be.
Subtle Signs You Might Notice
Beyond the two main symptoms, a collapsed lung can produce several other changes. Your heart rate may climb as your body compensates for reduced oxygen exchange. You might notice that one side of your chest doesn’t seem to expand as much as the other when you breathe. Some people feel a dry, hacking cough that comes on suddenly alongside the pain.
If you have a home pulse oximeter, a drop in your oxygen saturation reading can be an early clue. In at least one documented case, an unexplained drop on pulse oximetry was the first sign of a tension pneumothorax before other symptoms became obvious. A reading below your normal baseline, especially paired with chest pain, adds another data point suggesting something is wrong with your lung.
When It Becomes Life-Threatening
Most collapsed lungs are painful but manageable. A tension pneumothorax is the dangerous exception. This happens when air continues leaking into the chest cavity with no way to escape, building pressure that compresses the heart and major blood vessels. The symptoms escalate quickly: rapid breathing, a racing heart, and then signs of shock, including dangerously low blood pressure, dizziness, weakness, and visibly bulging veins in the neck.
Tension pneumothorax is a true emergency. If someone’s chest pain and breathing difficulty are getting worse by the minute, especially after an injury, call emergency services immediately.
Who Is Most at Risk
Collapsed lungs happen to people with no lung disease at all, a type called primary spontaneous pneumothorax. It’s three to six times more common in men than women, with U.S. incidence around 7.4 per 100,000 men per year. Tall, thin young men are the classic profile. Smoking, including cannabis, is a significant risk factor, as are genetic predispositions that cause tiny air-filled blisters (blebs) to form on the lung surface. These blebs can rupture without any obvious trigger.
People with existing lung conditions face a higher risk of what’s called secondary spontaneous pneumothorax. The most common underlying diseases include COPD, asthma, cystic fibrosis, and tuberculosis. Certain connective tissue disorders like Marfan syndrome and Ehlers-Danlos syndrome also weaken lung tissue enough to increase risk. If you have one of these conditions and develop sudden chest pain with breathing difficulty, a collapsed lung should be high on your list of concerns.
Trauma is the other major cause. A car accident, a hard fall, a sports collision, or even a fractured rib can puncture the lung lining and allow air to leak out. After any significant blow to the chest, new or worsening chest pain and shortness of breath should prompt immediate medical evaluation.
How Doctors Confirm It
You can’t diagnose a collapsed lung at home with certainty. The definitive answer comes from imaging. A chest X-ray is the standard first step and can reveal air in the chest cavity where it shouldn’t be. CT scans are more sensitive and serve as the gold standard for confirming smaller collapses that X-rays might miss.
Bedside ultrasound is sometimes used in emergency rooms, particularly for trauma patients, but recent research suggests it has significant limitations. A 2024 study of blunt trauma patients found that chest ultrasound missed 72% of pneumothoraces that CT later confirmed. Nearly a quarter of those missed cases were serious enough to require a chest tube. This means ultrasound alone isn’t reliable for ruling out a collapsed lung, and if your symptoms are concerning, pushing for a chest X-ray or CT is reasonable.
What Happens After Diagnosis
Treatment depends on the size of the collapse. A small pneumothorax, where only a thin rim of air surrounds the lung, may heal on its own with rest and monitoring. You’ll typically have repeat imaging over several hours to make sure the collapse isn’t expanding. Supplemental oxygen can speed reabsorption of the trapped air.
A larger collapse usually requires removing the trapped air. This involves inserting a small tube or needle through the chest wall to let the air drain out so the lung can re-expand. The procedure is done under local anesthesia, and while it’s uncomfortable, most people feel immediate relief in their breathing once the lung re-inflates. Hospital stays range from a couple of days to about a week depending on how quickly the air leak seals.
Recurrence Is Common
One of the most important things to know about a collapsed lung is that it tends to come back. In a study of 253 patients with primary spontaneous pneumothorax, just over half experienced a recurrence, with 37% of those repeat episodes happening within the first year. This means if you’ve had one collapsed lung, you should be especially vigilant about recognizing the symptoms again.
Quitting smoking is the single most impactful step to reduce recurrence risk. For people who’ve had multiple collapses, a surgical procedure can seal the area where air leaks occur and significantly lower the chances of it happening again. Your doctor will typically discuss this option after a second episode on the same side.