If you ask about breathwork, or search for it, you might hear various stories. Some call it the most relaxing experience of their week, whereas an online headline might claim that someone died doing it. If you’re deciding whether to book a session, or whether to try it at home, you’d like to know which is closer to the truth.
The warning lists online don’t help much. They are long, they disagree with each other, and many are copied from liability waivers, so it’s hard to tell which items are about your body and which are about someone’s insurance.
There’s a simpler way in. Almost every risk in breathwork follows from one physiological change in the body, the same change that produces the tingling and the heightened, unusual feeling people describe. Once you see it, the list makes sense: which reactions are expected, which conditions rule breathwork out and why, and what a safe session and a trained facilitator do about both.
Is breathwork safe?
For most healthy adults, guided breathwork under a trained and informed facilitator is low risk. How low depends on the style. Slow breathing carries very little risk. High-ventilation breathwork carries rare but serious risks for people with certain conditions. Holding your breath in water after over-breathing can be fatal.
“Breathwork” covers very different practices, and lumping them together is where most of the confusion starts. Researchers use the term high-ventilation breathwork for practices that deliberately increase how fast or how deeply you breathe (opens in new tab), sustained for minutes at a time. Conscious Connected Breathwork and Holotropic Breathwork belong here, and so do the fast rounds of Wim Hof-style practice. All of them sit within the wider practice of breathwork.
| Breathwork style | Examples | What it does | Main risk |
|---|---|---|---|
| Slow, paced breathing | box breathing, coherent breathing, 4-7-8, longer exhales | slows the breath and keeps carbon dioxide steady | very low |
| High-ventilation breathwork | Conscious Connected Breathwork, Holotropic Breathwork, Wim Hof-style rounds, breath of fire | lowers carbon dioxide for minutes at a time | rare but serious for certain conditions; strong emotion |
| Breath-holding, especially after over-breathing | Wim Hof-style retentions, freediving drills | delays the urge to breathe while oxygen keeps falling | blackout without warning; fatal in water |
Slow breathing is what the NHS recommends for stress, anxiety, and panic (opens in new tab). The rest of this article is mostly about high-ventilation breathwork.
For proportion, hospitals use a few minutes of deliberate over-breathing during routine brain-activity tests (EEGs). UK clinical guidance treats it as reasonably safe, with a small risk of seizures and of heart, breathing, and circulation events (opens in new tab). A national audit of 3,475 patients who did it found no significant heart or breathing problems (opens in new tab). A breathwork session lasts far longer than those few minutes, which is why your health, and the way a session is run, matter.
How does breathwork affect the body? One change behind most of the risks
Breathing more than your body needs lowers the carbon dioxide in your blood. The blood becomes slightly more alkaline, nerves become more excitable, and blood vessels narrow, including those in the brain. The sensations of breathwork and its risks come from that same chain.
Step by step:
- Carbon dioxide falls. You’re breathing it out faster than your body makes it. Light-headedness is often the first sign.
- The blood becomes more alkaline. Clinicians call this respiratory alkalosis. Less calcium is left free around your nerves, so they fire more easily and you experience tingling, then cramping hands (opens in new tab), known as tetany. In a brain already prone to seizures, the same excitability lowers the threshold for one.
- Blood vessels narrow. Low carbon dioxide constricts the vessels in the brain (opens in new tab) and reduces blood flow there. In a 2025 imaging study, blood flow to the brain fell by about 30 to 40% (opens in new tab) during a session. In the heart, over-breathing can bring on spasm of the coronary arteries in people prone to it, and cardiologists use it as a test for exactly that (opens in new tab).
- It reverses. When breathing returns to normal, carbon dioxide builds back up and the chain unwinds.
That is why the same breath can be an interesting, tingling hour for one person and a real risk for another. The chemistry is the same. The body it happens in is different. My article on how the breath changes your blood chemistry goes into the mechanism in more detail.
What are some side effects of breathwork? What’s expected, what’s uncomfortable, what’s serious?
Most of what people feel in breathwork is expected, and it passes within minutes once the breath slows. A smaller group of effects is unpleasant but usually harmless. A few are rare and serious, and those are what screening is for, which every professional breathwork facilitator should do.
| Effects | What to do | |
|---|---|---|
| Expected | Tingling in the hands, face, and feet; light-headedness; tetany (hands curling, jaw tightening); feeling hot or cold; yawning; tears or laughter | Nothing, or soften the breath; these pass as carbon dioxide recovers |
| Uncomfortable, usually harmless | Headache; nausea; feeling spacey or tired afterwards; anxiety during the session; aching muscles | Slow down, lengthen the exhale, then water, food, and rest |
| Rare and serious | Fainting; a seizure; chest pain or an irregular heartbeat; panic or distress that doesn’t settle; feeling detached or unreal for days | Stop; get medical help for physical symptoms, and talk to a clinician about psychological ones |
Which tier you land in depends on the dose, meaning how hard and how long you breathe, and on you. An NHS hospital leaflet on over-breathing describes its symptoms as very unpleasant but not harmful (opens in new tab), settling as breathing slows. That gives you a simple test, whatever anyone in the room tells you: expected effects ease when you soften the breath. If something doesn’t, stop and say so.
Nobody has yet counted how often serious problems happen in breathwork. In one recent study of screened, experienced practitioners, no adverse events were reported (opens in new tab), but that was a small group of people who knew what they were doing.
Who should not do breathwork? (Contraindications)
Don't do high-ventilation breathwork, or speak to your doctor first, if you have or have had any of the following
- pregnancy
- heart disease, angina, a heart attack in the last year, or uncontrolled high blood pressure
- a stroke, aneurysm, or other cerebrovascular disease, including moyamoya
- epilepsy or any seizure disorder
- significant lung disease, severe or poorly controlled asthma, or breathlessness at rest
- sickle cell disease or trait
- glaucoma or retinal detachment
- recent surgery or injury
- osteoporosis
- psychosis, schizophrenia, or bipolar disorder
- panic disorder, PTSD, severe anxiety, or dissociation (talk to your clinician first)
Each one is on the list for a physical or psychiatric reason, explained in the table below.
| Condition | Why it’s on the list |
|---|---|
| Pregnancy | In older animal studies, a mother’s over-breathing reduced blood flow to the placenta or the baby’s oxygen, and one study during labour found lower maternal carbon dioxide went with lower oxygen for the baby (opens in new tab). The evidence is thin, and breathwork studies and clinical practice exclude pregnancy as a precaution. See the pregnancy section below. |
| Heart disease and high blood pressure | Low carbon dioxide narrows blood vessels, and over-breathing can bring on coronary artery spasm. Clinical guidance treats a heart attack in the last year or unstable angina as an absolute reason not to over-breathe (opens in new tab). |
| Stroke, aneurysm, cerebrovascular disease | Blood flow to the brain drops sharply during high-ventilation breathwork. In a brain that is already injured, low carbon dioxide is likely to do more harm than good (opens in new tab). |
| Epilepsy or seizure disorders | Neurologists use over-breathing on purpose to provoke seizures during EEG tests (opens in new tab). |
| Asthma and lung disease | Asthma isn’t an automatic exclusion; it’s assessed case by case. Fast breathing of dry air can narrow the airways in people with asthma, and clinicians use it as a test for exercise-induced asthma (opens in new tab). Bring your inhaler, tell your facilitator, and talk to your doctor first if your asthma is severe or not well controlled. Breathlessness at rest rules out high-ventilation breathwork. |
| Sickle cell disease or trait | Clinical guidance lists it as an absolute reason not to over-breathe (opens in new tab). Strokes have been reported in children with sickle cell disease after routine over-breathing during EEGs (opens in new tab). |
| Glaucoma, retinal detachment, recent surgery or injury, osteoporosis | Screened case by case by facilitators, including me, as a precaution. I haven’t found research that sets out the risk, so treat these as conversations to have with your doctor, and with me when you book a breathwork session. |
| Psychosis, schizophrenia, bipolar disorder | Altered states can be destabilising, and breathwork research excludes these conditions (opens in new tab). |
| Panic disorder, PTSD, dissociation | Over-breathing can bring on panic in people prone to it. More on this below. |
Check with your doctor first, too, if you take regular medication for any of these, or if you’re unsure whether something applies to you.
I go into contraindications in more detail through a health screening form when you book a session with me. I read every health form myself before a session. If anything on it means the work isn’t safe for you, I say so, and you get a full refund.
Can breathwork cause seizures, fainting, or brain damage?
These are three separate worries with three short answers.
Seizures
Rarely, and mostly in people who already have epilepsy. Over-breathing lowers the threshold for a seizure, which is why neurologists use it during EEG tests and why epilepsy is excluded. In the UK audit of 3,475 patients (opens in new tab), the seizures it brought on were mostly brief absence seizures in children with suspected epilepsy.
Fainting
It can happen, which is one reason you lie down. Low carbon dioxide reduces blood flow to the brain, and light-headedness is common. Lying on a mat, there’s nowhere to fall. Standing, on a chair, at the wheel, or in water, a faint is a different matter.
Brain damage
There’s no evidence that breathwork causes lasting brain damage in healthy, screened adults. Blood flow to the brain does fall during high-ventilation breathwork, by up to about 40%, and it’s expected to recover as carbon dioxide returns to normal. Nobody has studied the long-term effects.
The figure comes from a 2025 imaging study (opens in new tab): blood flow fell by about 30% in the early minutes and about 42% once the breathing was sustained. The study didn’t measure recovery, but blood flow to the brain follows carbon dioxide closely (opens in new tab), so it rises again as breathing settles.
Holotropic Breathwork is a longer, more intense form of high-ventilation breathwork, so the same applies for longer. The concern is real for anyone whose brain or blood vessels are already vulnerable, which is why a recent stroke, an aneurysm, or a brain injury rules it out.
Breath-holding and water: where the deaths happened
The deaths linked to breathwork involved over-breathing followed by holding the breath, in or near water. Over-breathing removes the urge to breathe while oxygen keeps falling, so people black out without warning. Lying on a mat, that’s a faint. In water, it’s drowning.
The urge to come up for air is triggered mostly by rising carbon dioxide. Over-breathing empties it out first, so during a breath-hold oxygen can fall low enough to cause a blackout before you feel any need to breathe. A CDC report on 16 drownings from underwater breath-holding (opens in new tab) in New York State, four of them fatal, describes exactly this, and five involved deliberate hyperventilation. In Australia, this kind of blackout was implicated in 22 drowning deaths over 14 years (opens in new tab).
Three rules follow:
- Never practise breathwork in or near water, including the bath.
- Never practise it while driving, or anywhere a faint could hurt you.
- If a practice includes breath-holds, do them lying down on solid ground, and don’t push for a longer hold.
Can breathwork impact you emotionally and psychologically?
Yes, for some people. Long, activating sessions can bring up strong emotion. For people prone to panic, living with the effects of trauma, or with a fragile mental-health picture, they can leave things more unsettled for days or longer. A listing that calls a class “gentle” can’t promise it will feel gentle to your nervous system. This is where a facilitator trained in trauma-informed practice matters: they pace the session to what you can take in, stay with you through what comes up, check in with you afterwards, and know when to point you towards a clinician.
In one small study, three minutes of over-breathing brought on a panic attack in 9 of 13 people with panic disorder (opens in new tab), against 1 of 11 people without it. A session lasts far longer than three minutes. And in a survey of 324 people describing their latest session, those who had more challenging experiences reported lower well-being afterwards (opens in new tab).
Talk to your clinician, and make sure you’re working with a trained facilitator, before trying high-ventilation breathwork if you have:
- panic disorder, or frequent panic attacks
- PTSD or a significant trauma history
- episodes of dissociation, or of feeling unreal or detached
- a history of psychosis or bipolar disorder
- a current crisis, or a recent bereavement
Breathwork isn’t a treatment for any of these. It can sit alongside care from a clinician, and it shouldn’t replace it.
Catharsis isn’t the aim of a session with me, and that’s a safety decision as much as anything else. I guide people to breathe in through the nose and out through the mouth, which in an exercise study kept carbon dioxide higher (opens in new tab) than breathing through the mouth alone. Every session ends with 15 to 20 minutes of rest and a debrief. The aim is to stay within what your system can take in, sometimes called the window of tolerance, and to build from there. A big release is never the measure of a good breathwork session.
Is breathwork safe during pregnancy, or on your period?
Pregnancy
Avoid high-ventilation breathwork while you’re pregnant. Slow, gentle breathing is a different matter: it’s a standard part of preparing for birth, and UK guidance supports breathing and relaxation techniques in labour (opens in new tab).
Some facilitator trainings, including mine, give specific guidance on breathwork in pregnancy, and it differs by trimester. If you’re pregnant, tell your facilitator before you book, so they can suggest what suits your stage, and check anything beyond gentle breathing with your midwife or doctor. The caution about faster breathing comes from older, mostly animal research in which a mother’s over-breathing reduced blood flow to the placenta or the baby’s oxygen. Most breathwork research excludes pregnancy for the same reason.
Your period
There’s no evidence that having your period is a reason to avoid breathwork, and no research on it either way. If you’re tired, light-headed, or bleeding heavily, a slower, shorter practice is the sensible choice.
How can you tell if a breathwork session is safe?
A safe session is screened, paced, watched, and managed with expert interventions before, during, and after the session. Most importantly, it empowers you to slow down or stop at any point, instead of asking you to push yourself and keep breathing. You can check most of this before you book.
- A health form before the session, and someone who actually reads it.
- A trained facilitator who stays present and watches, in the room or on camera.
- You lie down, somewhere a faint wouldn’t hurt you.
- You can slow down or stop at any time, and nobody asks you to push through.
- A rest phase before you get up, and time to talk afterwards.
- No promise of a breakthrough, and no pressure to have one.
- Recordings have limits. A video can’t see you or slow you down, so keep high-ventilation practice for guided sessions, at least at first.
Here’s how I run my group and 1:1 breathwork sessions. You fill in a detailed, confidential health form before the session. I read each form myself to assess your suitability and guide you accordingly. The breath goes in through the nose and out through the mouth. Active breathing lasts 45 to 50 minutes, followed by 15 to 20 minutes of rest and a debrief. If the form shows breathwork isn’t right for you, I’ll tell you, and you get a full refund.
What should you do if you feel unwell during or after breathwork?
During a session, slow down and breathe gently through your nose; most symptoms ease within minutes. Afterwards, drink water, eat, and rest before driving. Get medical help for chest pain, fainting, or a sudden severe headache, and see a clinician if distress lasts more than a few days.
During a session
- Stop the active breath and let it slow. NHS advice on over-breathing suggests slow, regular breathing at about 8 to 10 breaths a minute (opens in new tab).
- Tell your facilitator what you’re feeling.
- Sit up slowly, and only when you feel steady.
- Don’t breathe into a paper bag. First-aid guidance advises against it, because it can make things worse (opens in new tab).
Afterwards
- Drink water, eat something, and rest.
- Don’t drive until you feel steady.
- A tired or emotionally raw day is common. Go easy on yourself, and keep the evening light if you can. Talk to your facilitator, who can guide you in managing these emotions.
Get help
- Call emergency services for chest pain, fainting, a seizure, a sudden severe headache, or breathlessness that doesn't settle with slow breathing.
- See a doctor if physical symptoms last beyond the day.
- Talk to a clinician as well as your facilitator if anxiety, low mood, or a sense of unreality lasts more than a few days.
Where this leaves you
Breathwork’s risks are knowable. Most of what you’ll feel is expected, and it eases when the breath slows. The serious risks are rare, they belong to specific conditions, and a health form exists to catch them. The rest comes down to choosing a session that is paced and properly held.
If you’d like to see what that looks like in practice, you can book a private online breathwork session with me.