Hydroxy: breathing hydrogen and oxygen, explained

Hydroxy is a session where you breathe a mix of molecular hydrogen and oxygen through a soft nasal cannula, and drink a glass of hydrogen-rich water alongside it. Hydrogen is the smallest molecule there is. It is inert, it has no taste or smell, and your body clears it within the hour. Researchers have spent the last two decades asking whether that tiny, harmless gas does anything useful once it is inside you. The short answer: there is a real mechanism, a growing pile of small human studies, and no big claims that survive scrutiny yet. Here is the longer version.

What molecular hydrogen is

Molecular hydrogen, written H2, is two hydrogen atoms bonded together. In the body it is unusual for one reason: it is so small and so neutral that it passes through cell membranes, into mitochondria and even across the barrier into the brain without needing any transport. Almost nothing else you can inhale or drink does that. It is also naturally present in small amounts, because the bacteria in your gut produce it when they ferment fibre. So your body has seen hydrogen before. What a Hydroxy session does is raise the amount for a short time.

Why it is studied as a selective antioxidant

The research interest started with a 2007 paper in Nature Medicine by Ohsawa and colleagues. In cell cultures and in rats, hydrogen reacted with the two most damaging types of free radical, the hydroxyl radical and peroxynitrite, while leaving the milder ones alone. That word, selective, is why scientists took notice. Ordinary antioxidant supplements are blunt. They mop up everything, including the small amounts of oxidative stress your body uses as a signal, for example to adapt to exercise. A molecule that only reacts with the worst offenders would be a different kind of tool. Whether it translates to something you would notice is the question the human studies try to answer.

What the human evidence looks like

Early, small and mostly about exercise. That is the fair summary.

• A 2023 systematic review and meta-analysis by Zhou and colleagues pooled 19 studies with 402 healthy adults. Hydrogen, mostly as water and sometimes as gas, was linked to lower perceived fatigue and lower blood lactate during hard exercise. It did not improve aerobic capacity. The effect on fatigue was larger in untrained people than in trained athletes.
• A 2019 review by LeBaron and colleagues in the Canadian Journal of Physiology and Pharmacology went through the sports literature and reached a similar place: promising signals on recovery and fatigue, small samples, inconsistent doses, and a need for bigger trials.
• Studies on sleep, mood, skin and general wellbeing exist, but they are fewer and thinner. People report benefits. The trial evidence is not there yet.

Our grade: some evidence for reduced fatigue and faster recovery around exercise, early evidence for everything else. Nobody should be told that hydrogen treats anything, and we do not say it.

One thing the literature does agree on is safety. Hydrogen does not react with anything in the body except those radicals. It is not metabolised, it does not build up, and it leaves through your lungs within about an hour. At the concentrations used in a Hydroxy session it is nowhere near flammable. Trials that looked for side effects did not find any beyond the occasional dry nose from the cannula. This matters because it means the downside of trying it is small. The question is only whether the upside is worth your time and credits, and that is a fair thing to test for yourself.

How a session goes at Freezlab

1. You sit down in a comfortable chair. Nothing to change into.
2. Reception fits a soft nasal cannula, the same kind used for oxygen in hospitals. It rests under your nose and loops over your ears.
3. The machine produces the hydrogen and oxygen mix on the spot by splitting water. You breathe normally. There is nothing to feel, taste or smell.
4. You get a glass of hydrogen-rich water to drink during the session.
5. Most members read or close their eyes. It is one of the calmer things in the building.

A session costs 2 credits, or €15 as a single.

Honest expectations

You will not feel anything during a Hydroxy session, and probably nothing dramatic afterwards. That is expected, because the studies measure things like lactate and perceived fatigue after exercise, not a rush. If you train hard and want to test it, use it after your sessions for a few weeks and pay attention to how the next day feels. If you do not train much, treat it as a quiet sit-down with a possible small bonus. Deciding after a month that it does nothing for you is a perfectly good outcome.

How it fits into a week at Freezlab

Hydroxy is easy to stack. At 2 credits it sits naturally after cryotherapy or while your legs are in the Normatec boots in the Recovery Room. Two or three times a week is the rhythm most members settle into. Read the details on the Hydroxy page and book a session. New to Freezlab? The Trial Membership gives you enough credits to try it alongside everything else for a month.

Freezlab does not diagnose, treat or cure medical conditions. If you are unsure whether a therapy suits you, talk to your doctor.