Medical note: This article is for general education and does not replace individualized medical advice, diagnosis, or treatment from a qualified clinician. Chest pain, fainting, severe shortness of breath, new weakness, or symptoms of a heart attack require urgent medical care.
Long COVID has a special talent for making ordinary activities feel suspiciously ambitious. A short walk can become an expedition. A flight of stairs may suddenly have the emotional intensity of climbing Everest in flip-flops. For some people, lingering fatigue, breathlessness, palpitations, chest discomfort, and exercise intolerance raise an uncomfortable question: is the heart still feeling the effects of COVID-19?
One emerging area of research is hyperbaric oxygen therapy, often called HBOT. In a small randomized trial, researchers found that some people with post-COVID symptoms and subtle abnormalities in heart function improved after a course of HBOT. The results are promising, especially for a group of patients whose standard heart tests may look normal while they still feel anything but normal. But promising is not the same as proven, and a hyperbaric chamber is not a magic submarine that fixes every long COVID symptom on contact.
This article explains what researchers found, why heart symptoms can occur after COVID-19, what HBOT actually involves, and how to think about this treatment without getting swept away by hype or fear.
Why Long COVID Can Affect the Heart
Long COVID, also called post-COVID condition, can involve many body systems. The symptoms are broad and occasionally feel like a very unhelpful buffet: fatigue, brain fog, sleep problems, dizziness, shortness of breath, fast heart rate, headaches, chest pain, and symptoms that worsen after physical or mental exertion.
Heart-related symptoms do not automatically mean someone has heart disease. Palpitations, for example, can be connected to stress, dehydration, medications, poor sleep, autonomic nervous system changes, or an abnormal heart rhythm. However, clinicians take persistent symptoms seriously because post-COVID conditions can involve myocardial injury, rhythm disturbances, vascular changes, blood clotting issues, inflammation, and dysautonomia, including conditions such as postural orthostatic tachycardia syndrome, or POTS.
COVID-19 may affect the cardiovascular system through several overlapping pathways. Inflammation can disrupt blood vessel function, alter the body’s clotting system, and place extra stress on the heart. Severe acute infection can also strain the cardiovascular system because the body is working hard to maintain oxygen delivery. Even after recovery, some people continue to experience symptoms that suggest the heart, blood vessels, lungs, nervous system, or all of the above are still trying to get their group project together.
That is why a persistent racing heart, chest discomfort, fainting, swelling in the legs, worsening breathlessness, or a sharp drop in exercise capacity deserves medical evaluation rather than a casual shrug and another energy drink.
What Is Hyperbaric Oxygen Therapy?
Hyperbaric oxygen therapy involves breathing nearly pure oxygen inside a pressurized chamber. The chamber pressure is higher than normal atmospheric pressure, allowing the lungs to take in more oxygen than they could while breathing regular air at sea level. That oxygen dissolves into the bloodstream and can increase oxygen delivery to tissues.
HBOT is already used for specific medical conditions, including decompression sickness, carbon monoxide poisoning, certain serious infections, radiation tissue injury, and selected nonhealing wounds. During a typical session, a patient lies in a clear single-person chamber or sits in a larger chamber with other patients. Treatment commonly lasts around 90 minutes to two hours, depending on the condition and protocol.
The possible appeal for long COVID is easy to understand. Researchers are exploring whether greater oxygen delivery, changes in inflammation, improved blood vessel function, and tissue repair signaling might help people whose symptoms persist after infection. These theories are biologically plausible, but biology has a habit of being more complicated than a motivational poster.
The Study That Put HBOT and Heart Function in the Spotlight
A 2023 randomized, double-blind, sham-controlled study examined whether HBOT could improve heart function in people with post-COVID symptoms lasting at least three months. The trial included 60 participants who received either 40 HBOT sessions or sham sessions.
Researchers used echocardiography to assess cardiac function before treatment and again one to three weeks after the treatment period. Importantly, they looked at a measurement called global longitudinal strain, or GLS.
Why Global Longitudinal Strain Matters
Many people are familiar with ejection fraction, a common measurement of how much blood the left ventricle pumps out with each beat. It is useful, but it does not catch every subtle problem. A person can have a normal ejection fraction while still showing early or mild changes in how the heart muscle contracts.
GLS is a more sensitive echocardiographic measurement that tracks the heart muscle’s shortening during contraction. Think of it as checking whether the heart is doing its job with smooth coordination rather than simply asking whether it showed up to work. Reduced GLS may suggest subtle left ventricular dysfunction even when standard ejection fraction looks normal.
In the trial, 29 of the 60 participants had reduced GLS at baseline. Among those participants, the HBOT group showed a statistically significant improvement in GLS compared with the sham group. The average GLS changed from approximately -17.8 to -20.2 after HBOT, moving closer to a healthier range of heart muscle contraction. The authors concluded that HBOT may promote recovery of left ventricular systolic function in selected people with post-COVID condition, while emphasizing that further study is needed.
What the Results Mean and What They Do Not Mean
The study is encouraging for several reasons. It was randomized, double-blind, and sham-controlled, which helps reduce the chance that expectations alone explain the findings. It also focused on a more sensitive marker of heart function rather than relying only on standard ejection fraction.
Still, this was a relatively small study. It does not prove that every person with long COVID and fatigue, palpitations, or shortness of breath should receive HBOT. It also does not prove that HBOT prevents heart failure, eliminates cardiac risk, or permanently cures long COVID.
Other research has produced more mixed results. A 2025 placebo-controlled trial using a shorter, 10-session HBOT course did not find a meaningful short-term advantage over placebo for long COVID symptoms. Another 2025 trial examining different oxygen doses in a hyperbaric setting also found no significant effect and cautioned against promoting HBOT indiscriminately before stronger evidence is available.
That does not mean the earlier heart-function findings were meaningless. It means the big unanswered question is who benefits, from which protocol, and for which long COVID pattern? The answer may differ for someone with reduced GLS, someone with POTS-like symptoms, someone with post-exertional malaise, and someone whose main issue is insomnia or brain fog.
Could HBOT Help Long COVID Symptoms Beyond the Heart?
Several small studies and reviews have explored whether hyperbaric oxygen therapy could improve fatigue, cognition, sleep, pain, mood symptoms, quality of life, and exercise tolerance in people with long COVID. Some studies have reported positive changes, including improvements in cognitive symptoms and quality-of-life scores.
However, long COVID research is difficult to interpret because the condition is not one neat diagnosis with one predictable course. Symptoms naturally fluctuate. Some people gradually improve over time. Placebo effects can be strong, particularly when a treatment feels futuristic and comes with a chamber that resembles something from a science-fiction movie.
For that reason, HBOT should be viewed as an investigational or emerging option for long COVID rather than a universally established treatment. The evidence is evolving, and larger trials with long-term follow-up are still needed.
Who Should Consider a Heart Evaluation After Long COVID?
Not everyone with long COVID needs extensive cardiac testing. But persistent or concerning symptoms should be discussed with a clinician, especially when they interfere with daily life or worsen over time.
Symptoms Worth Discussing Promptly
- Chest pain, pressure, heaviness, or discomfort with exertion
- New or frequent palpitations
- Shortness of breath that is new, worsening, or out of proportion to activity
- Fainting, near-fainting, or persistent dizziness when standing
- Leg swelling, unexplained weight gain, or waking up short of breath
- A major drop in exercise tolerance after COVID-19
- Symptoms that appear during exercise and improve only with rest
Depending on the situation, a clinician may recommend an ECG, blood tests, echocardiogram, ambulatory rhythm monitor, cardiac MRI, pulmonary testing, or cardiopulmonary exercise testing. Large post-COVID programs often tailor testing to the patient’s symptoms rather than ordering every test under the sun and hoping the sun fills out the insurance paperwork.
HBOT Safety: More Than Just “Relaxing in an Oxygen Tube”
Hyperbaric oxygen therapy is generally considered safe when it is prescribed appropriately and delivered in a qualified medical setting. But it is still a medical treatment, not a spa add-on wedged between a facial and a juice cleanse.
Possible side effects include ear pain, sinus pressure, temporary vision changes, fatigue, and middle-ear injury. Less common but more serious complications can include lung collapse and oxygen-related seizures. Claustrophobia can also make chamber treatment difficult. People with diabetes may need glucose monitoring because HBOT can affect blood sugar.
Safety also includes the facility itself. Oxygen-rich environments increase fire risk, which is why medical hyperbaric programs use strict procedures for clothing, electronics, skin products, equipment maintenance, and patient monitoring. The U.S. Food and Drug Administration has warned providers and facilities to follow safety instructions closely after reports of serious injuries and deaths associated with HBOT device fires.
People considering HBOT should ask whether the facility is medically supervised, whether it has trained hyperbaric staff, how emergency procedures work, and whether a physician has reviewed their medical history. A soft-sided wellness chamber with vague promises of “cellular reset” is not interchangeable with medically supervised HBOT.
Questions to Ask Before Paying for Hyperbaric Oxygen Therapy
HBOT courses can be time-intensive and expensive, especially when dozens of sessions are recommended. Insurance coverage for long COVID-related HBOT may be limited because it is not an established standard indication for the condition.
Before committing, ask these questions:
- What specific symptom or abnormal test result are we trying to improve?
- Has my heart, lung, rhythm, or autonomic function been evaluated first?
- Is there evidence that my particular long COVID pattern matches people studied in HBOT trials?
- What protocol is being recommended, and why?
- How will progress be measured beyond “Do you feel different?”
- What are the medical risks based on my health history?
- What happens if symptoms worsen or I develop ear, sinus, or breathing problems?
A good clinic should welcome these questions. A clinic that responds with “Just trust the oxygen” may not be the ideal place to hand over your credit card.
What People Can Do While Research Continues
For many people with long COVID, the most useful plan is not one dramatic treatment but a carefully paced, symptom-based approach. That may include sleep support, hydration, nutrition, treatment for asthma or other lung problems, medication review, heart-rate management, physical therapy, occupational therapy, mental health support, and rehabilitation tailored to the person’s energy limits.
Pacing is particularly important for people with post-exertional malaise, where pushing harder can cause a delayed symptom crash. “No pain, no gain” is not a universal health law. In long COVID, sometimes it is closer to “no pacing, no groceries for three days.”
Patients with suspected POTS or other autonomic symptoms may benefit from individualized strategies such as adequate fluids, clinician-guided salt intake when appropriate, compression garments, medication, and carefully structured rehabilitation. Anyone with new heart symptoms should avoid launching into a heroic exercise comeback until they have been evaluated.
Experience: What a Hyperbaric Oxygen Therapy Journey May Feel Like
The experience of considering HBOT for long COVID can be emotionally complicated. Many people reach this point after months of appointments, normal-looking tests, partial answers, and the exhausting effort of explaining why they can be functional one day and flattened the next. The idea of a treatment that might improve oxygen delivery or heart function can feel hopeful. It can also feel like one more thing to research while already tired enough to consider lying down as a personality trait.
Imagine a composite patient named Jordan. Jordan had COVID-19 more than six months ago and recovered from the initial fever and cough. But running errands now causes a fast heart rate, breathlessness, and a strange “battery draining” feeling afterward. An ECG is normal. Basic blood work is mostly reassuring. Still, Jordan’s symptoms are real and disruptive.
A clinician orders an echocardiogram with strain imaging and finds mildly reduced global longitudinal strain despite a normal ejection fraction. This does not automatically mean severe heart disease. It does mean the conversation becomes more specific. Rather than chasing every possible treatment on social media, Jordan can ask whether the abnormality fits the available HBOT research, whether other causes need to be ruled out, and whether a supervised treatment trial makes sense.
At a legitimate medical hyperbaric center, the first appointment may involve reviewing medical history, medications, ear and sinus problems, lung conditions, diabetes, prior surgeries, anxiety around enclosed spaces, and the reason for referral. The patient may be taught how to equalize ear pressure by swallowing, yawning, or gently blowing with the nose pinched. It sounds simple until your ears decide to become dramatic during descent.
During treatment, the chamber gradually pressurizes. Some people describe a feeling similar to airplane takeoff, especially in the ears. Once pressure is stable, the session is usually quiet. Patients may rest, watch approved entertainment, listen to audio, or simply stare into the middle distance and reconsider every life choice that led them into a transparent tube on a Tuesday morning.
After several sessions, some patients report better energy, clearer thinking, improved sleep, or easier recovery after activity. Others notice little change. Some experience ear discomfort, sinus pressure, fatigue, or temporary vision changes. A responsible program tracks symptoms, vital signs, side effects, and meaningful functional goals rather than assuming that every session equals progress.
The most realistic patient experience is not “HBOT fixed everything.” It is usually more nuanced: a structured trial, careful monitoring, honest expectations, and regular reassessment. For a person with long COVID and reduced heart strain, HBOT may eventually become a useful tool. For another person, the better answer may be cardiac rehabilitation, autonomic treatment, pacing, sleep management, or a completely different approach. The goal is not to find the fanciest chamber. The goal is to find the safest, most evidence-based path back toward a life that feels livable again.
Conclusion
Hyperbaric oxygen therapy may improve subtle heart dysfunction in a subset of people with long COVID, particularly those with reduced global longitudinal strain despite a normal ejection fraction. A small randomized controlled trial showed improved GLS after a 40-session HBOT protocol, but later research has been mixed, and experts still need larger studies to determine who benefits most.
For now, HBOT should be approached as an emerging, medically supervised option rather than a guaranteed cure. The smartest first step is a careful evaluation of persistent chest pain, breathlessness, palpitations, dizziness, or exercise intolerance. When the heart is involved, curiosity is healthy. Guesswork is not.
