A hiatal hernia can make breathing harder, and this is more common than most people realize. In one study of patients with giant paraesophageal hernias, roughly half reported shortness of breath as a symptom before surgery.1Elsevier / The Journal of Thoracic and Cardiovascular Surgery. Repair of giant paraesophageal hernias routinely produces improvement in respiratory function The connection between the two is not obvious, which is why breathlessness caused by a hiatal hernia often gets blamed on the lungs or the heart before anyone thinks to look at the diaphragm.
How a Hernia in the Diaphragm Affects Your Lungs
Your diaphragm is both a breathing muscle and a barrier between your chest and abdomen. A hiatal hernia occurs when part of the stomach, and sometimes other abdominal organs, pushes up through the opening (hiatus) in the diaphragm into the chest cavity. Once abdominal tissue is sitting where your lungs normally expand, two things happen. First, the lungs have less physical room to inflate fully. Second, the herniated tissue can press against the airways and restrict airflow. Surgical repair improves breathing measures precisely because it removes that tissue from the chest and restores the space the lungs need to expand.2SpringerOpen. The effect of surgical repair of hiatal hernia on pulmonary function: a systematic review and meta-analysis
Think of it like trying to take a deep breath while someone is pressing a pillow against your chest. The lungs themselves are fine, but they cannot do their job because something external is crowding them. That mechanical compression is the most direct way a hiatal hernia interferes with breathing, and it is the one doctors check for on imaging.
Size Makes a Big Difference
Not every hiatal hernia causes noticeable breathing trouble. Small sliding hernias, where a little bit of the stomach slips above the diaphragm and slides back down, are extremely common and rarely affect lung function in any measurable way. The hernias most likely to cause breathlessness are the large ones, particularly paraesophageal hernias, where a significant portion of the stomach (or other organs) sits permanently in the chest.
Research confirms a dose-response pattern: the bigger the hernia, the more lung capacity drops. One study grouped patients by hernia size and found that total lung capacity and vital capacity both fell as hernias got larger. That said, the average values in each group were still within normal range, and only about 14% of patients had outright abnormal lung volumes.3Wiley Online Library. Changes in lung volumes and gas trapping in patients with large hiatal hernia This means most people with even a large hiatal hernia are not walking around with dramatically impaired lungs. What they experience instead is a subtle reduction in how deeply they can breathe, which shows up mainly during exertion, when you need that extra capacity and it is not there.
This is partly why the symptom is so easy to miss or misattribute. If your resting oxygen levels are fine and your lung function tests look close to normal, a doctor might not immediately connect your exercise breathlessness to a hernia. The impairment is real but modest in most cases, and it tends to creep up rather than announce itself.
A Surprising Route Through the Heart
Mechanical lung compression is not the only way a large hiatal hernia makes you feel short of breath. There is a cardiovascular pathway that is less intuitive but well documented. When a large hernia sits in the chest, it can physically press on the left atrium, the heart chamber that receives oxygenated blood from the lungs. That compression raises the pressure in the pulmonary veins, which can lead to fluid leaking into the lung tissue and reduced lung flexibility.4Journal of the American College of Cardiology. Left Atrial Compression and the Mechanism of Exercise Impairment in Patients With a Large Hiatal Hernia
The result feels a lot like early heart failure: you get winded during activity, your exercise tolerance drops, and the usual cardiac workup does not find a clear explanation. This is one of those diagnostic traps in medicine. Patients with a large hiatal hernia sometimes end up seeing a cardiologist for breathlessness on exertion, and if nobody thinks to image the hernia, the actual cause stays hidden. The heart itself is structurally fine; it is just being squeezed from the outside.
This also explains why some patients notice their breathlessness is worse after eating a large meal. A full stomach that is already displaced upward through the diaphragm takes up even more space and presses harder on adjacent structures, including the left atrium. If you find yourself unusually short of breath after eating, and you have a known hiatal hernia, this mechanical compression is a likely reason.
Acid Reflux, Microaspiration, and Airway Irritation
Hiatal hernias are best known for causing gastroesophageal reflux, and reflux itself has its own pathway to breathing problems. When stomach acid washes up into the esophagus, tiny amounts can spill over into the airways. This is called microaspiration, and hiatal hernias increase the risk of it happening.5Elsevier. Diffuse parenchymal lung disease with micro aspirations in presence of hiatal hernia The aspirated material irritates the lining of the airways, triggering inflammation, mucus production, coughing, and in some cases bronchospasm, where the airways tighten reflexively.
If you have both a hiatal hernia and chronic cough, recurrent throat clearing, or a feeling that your asthma medications are not working well, microaspiration is worth considering. Some people are treated for asthma for years before the reflux connection is identified. The clue is often that breathing difficulty tends to be worse at night or when lying flat, since gravity no longer keeps stomach contents from reaching the throat. Elevating the head of the bed and managing reflux with medication can reduce these airway symptoms even without hernia surgery.
This reflux-to-airway connection is separate from the direct mechanical compression described above. A person with a moderate hiatal hernia that is not large enough to physically crowd the lungs can still have significant breathing symptoms if reflux and microaspiration are the main issue. In practice, many people with large hernias have both mechanisms working at once, which is part of what makes the breathlessness feel disproportionate to what any single test reveals.
Why This Symptom Gets Overlooked
Shortness of breath is one of those symptoms that points in a hundred directions. When someone reports it, the standard workup runs through the lungs first, then the heart, then less common causes. A hiatal hernia is rarely at the top of the differential diagnosis for dyspnea, even though research shows it is a common symptom. In the study of giant paraesophageal hernias, breathlessness was reported by 52% of patients, making it the third most common complaint behind heartburn and early satiety.1Elsevier / The Journal of Thoracic and Cardiovascular Surgery. Repair of giant paraesophageal hernias routinely produces improvement in respiratory function
Part of the diagnostic difficulty is that routine pulmonary function tests often come back normal or near-normal, as the lung volume data mentioned earlier suggest. A chest X-ray might show the hernia, but if the clinician is focused on ruling out pneumonia or fluid around the lungs, they may note the hernia and move on without connecting it to the breathing complaint. CT scans are better at showing the size and position of the hernia relative to surrounding structures, and they are increasingly what clinicians rely on when hernia-related breathlessness is suspected.
If you have a known hiatal hernia and are experiencing unexplained breathlessness, especially on exertion or after meals, it is worth bringing up the hernia with your doctor rather than assuming it is unrelated. Many people know they have a hiatal hernia from a previous endoscopy or imaging study but have never been told it could affect their breathing.
How Much Surgery Helps
One of the strongest pieces of evidence that hiatal hernias truly cause breathing problems is what happens after they are repaired. Surgical correction of large paraesophageal hernias consistently improves both subjective breathlessness and objective measures of lung function. Importantly, this improvement occurs regardless of whether the patient had a pre-existing lung condition, which rules out the possibility that the breathing benefit is just from treating some coincidental lung problem during the same hospital stay.6Oxford Academic. The other explanation for dyspnea: giant paraesophageal hiatal hernia repair routinely improves pulmonary function
A systematic review of studies measuring lung function before and after hernia repair found improvements in measures of airflow and total lung capacity, consistent with the idea that removing abdominal organs from the chest restores room for the lungs to expand and relieves any airway compression.2SpringerOpen. The effect of surgical repair of hiatal hernia on pulmonary function: a systematic review and meta-analysis For patients whose main complaint is breathlessness rather than heartburn, this matters because it means repair can be justified even when reflux symptoms are mild. The respiratory benefit alone can be clinically meaningful.
That said, not everyone with a hiatal hernia and some breathlessness needs surgery. Surgical repair is typically reserved for large or symptomatic paraesophageal hernias, hernias that are causing complications like anemia or obstruction, or cases where the breathing impairment is significant enough to affect quality of life. Small sliding hernias that cause occasional reflux and mild breathlessness are usually managed with medication and lifestyle changes. The decision is made case by case, weighing the severity of symptoms against the risks of the operation.
When Breathing Difficulty Becomes Urgent
Most hernia-related breathlessness develops gradually and is more of a nuisance than an emergency. But there are scenarios where a hiatal hernia and breathing difficulty together require prompt medical attention. If a paraesophageal hernia becomes incarcerated, meaning the stomach gets trapped above the diaphragm and cannot slide back down, the compression of the lungs and heart can worsen acutely. In rare cases, the trapped stomach can twist (a condition called gastric volvulus), cutting off blood supply and causing severe chest pain, difficulty swallowing, and worsening respiratory distress.
Sudden onset of severe shortness of breath in someone with a known large hiatal hernia, especially if accompanied by chest pain or inability to vomit despite feeling nauseous, warrants a trip to the emergency room. These situations are uncommon, but they are surgical emergencies when they happen. The more typical experience is a slow, grumbling decline in exercise tolerance that the person adapts to over months or years, not recognizing how much breathing capacity they have lost until it is measured or until it improves after treatment.
Other Conditions That Overlap
Because a hiatal hernia can mimic heart and lung disease, it is worth knowing which conditions frequently get confused with hernia-related breathlessness. Asthma is a common one, particularly when microaspiration-driven airway irritation is the main mechanism. Patients are given inhalers that help somewhat but never fully control the symptoms, because the root issue is reflux rather than allergic or inflammatory airway disease. Chronic obstructive pulmonary disease (COPD) is another, especially in older adults who have both a large hernia and some age-related decline in lung function. The hernia compounds the COPD, making it look worse on testing than the lung disease alone would predict.
Heart failure with preserved ejection fraction, where the heart pumps normally but fills stiffly, is perhaps the trickiest overlap. Left atrial compression from a hernia raises pulmonary pressures in a pattern that can look similar on echocardiography, and both conditions cause breathlessness on exertion that improves with rest.4Journal of the American College of Cardiology. Left Atrial Compression and the Mechanism of Exercise Impairment in Patients With a Large Hiatal Hernia The distinguishing feature is that hernia-related compression resolves with surgical repair, while true heart failure does not. Getting the diagnosis right matters, because the treatments are completely different.
Anxiety-related breathlessness also enters the picture. When standard tests come back normal and a patient keeps reporting dyspnea, there is a temptation to label it as anxiety-driven hyperventilation. For some patients with unrecognized hernia-related compression, this means years of being told the problem is psychological when there is a structural cause sitting right there on the imaging that nobody connected to the symptom. If you have been told your breathlessness is “just anxiety” but you also have a known hiatal hernia, it is reasonable to push for a closer look at the relationship between the two.