Is breathwork safe? Wim Hof, the real risks, and what’s proven

What “breathwork” means

“Breathwork” is an umbrella term. It usually means practices where you deliberately breathe faster or deeper than you need to: Wim Hof breathing, holotropic breathwork, conscious connected breathing, rebirthing, or yoga techniques like kapalabhati. Common effects include lightheadedness, visual disturbances, tingling, palpitations, shakiness, anxiety, and cramped hands.¹

Holotropic breathwork was developed in the 1970s by Stanislav and Christina Grof. It involves very fast, deep breathing, often for hours, with evocative music and a sitter.¹ In a study of experienced practitioners, a bigger drop in carbon dioxide went along with deeper altered states of consciousness. But people in the same room who just breathed normally experienced some of it too, so the group, the music, and the setting play a part.²

What the Wim Hof study actually measured

The best-known study dates from 2014. Twelve young men trained with Wim Hof for ten days in meditation, cold exposure including ice water, and a breathing technique: about 30 forceful breaths, then exhale and hold for two to three minutes. During the exercise, the stress hormone adrenaline rose sharply, blowing off carbon dioxide made their blood strongly alkaline, and at the end of each hold, oxygen saturation briefly dropped to around 50 percent.³

The study is often cited as if the method strengthens the immune system. But what it measured was a short reaction triggered in the lab, in twelve trained versus twelve untrained men. It doesn’t show which part of the training did what, whether breathing, cold, or meditation, or whether any of it matters in everyday life; the authors say so themselves.³

The overall evidence

A systematic review found only eight studies on the Wim Hof Method through July 2022, each with 15 to 48 participants, 86 percent of them men. The authors rate the quality of the studies as very low and say all results should be read with caution.⁴

The largest blinded study of fast breathwork with breath holds so far followed 200 young, healthy adults for three weeks. The comparison group breathed calmly, 15 times a minute, with short pauses. Both groups felt less stressed afterward, by the same amount.⁵ In another study, calm cyclic sighing actually lifted mood the most over a month, more than fast breathing with holds.⁶ These studies tested the techniques, not the nowa app.

The biggest risk: water

Fast, deep breathing lowers the carbon dioxide in your blood, and carbon dioxide is what normally triggers the urge to breathe. If you then hold your breath underwater, that urge comes later while oxygen keeps dropping, and you can black out without warning. In a CDC report, all four people who died while holding their breath underwater had deliberately hyperventilated first, even though they were very strong swimmers.⁷

1. During a normal breath hold, carbon dioxide rises. At some point a strong urge to breathe kicks in, and you surface.
2. If you hyperventilate first, you start with little carbon dioxide. The urge to breathe comes much later.
3. Oxygen still drops as usual, though. Hyperventilating barely stocks up any extra.
4. So oxygen can fall too low before the urge to breathe warns you. Underwater, blacking out can be fatal.

Play again

The provider itself warns about this too: intense breathing over several rounds can rarely cause fainting, which could be very dangerous in or near water or while driving. Practice only sitting or lying down.⁸ The provider calls lightheadedness and tingling harmless. The tingling comes from nerve fibers becoming overexcitable when you overbreathe; with stronger overbreathing, muscles can cramp, too.⁹

Calm vs. activating: the difference

The table sums up the studies in this article and in When breathing exercises make you anxious or dizzy. Only one study compared both kinds directly.⁶

Common questions

Is breathwork dangerous?

Nobody knows exactly how often things go wrong on dry land. A review of randomized studies found no side effects directly attributed to fast breathing, but only about one in five studies recorded side effects at all.¹ What’s deadly dangerous is fast breathing before going underwater.⁷

Does the Wim Hof Method boost your immune system?

That hasn’t been shown. The well-known study measured a short reaction triggered in the lab in twelve trained men, combined with cold and meditation.³ The overall evidence is very thin.⁴

Does Wim Hof breathing give you more oxygen?

No. During the holds, saturation even dropped briefly to around 50 percent.³ Why deep breathing barely adds oxygen is explained in Does deep breathing give you more oxygen?

Why do I get tingly, and why do my hands cramp?

Overbreathing lowers carbon dioxide, and nerves in your skin and muscles become more excitable. First it tingles; with stronger overbreathing, muscles can cramp.⁹ Go back to normal breathing right away.

What about 9D breathwork and similar trends?

I couldn’t find any study on “9D breathwork.” There’s also no study behind the claim that breathwork releases the body’s own DMT. What has been shown is that a strong drop in carbon dioxide goes along with altered states of consciousness.²