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What is Hydrogen Water?

Written by Ana Aleksic, MSc (Pharmacy) | Last updated:
Jonathan Ritter
Puya Yazdi
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology), Puya Yazdi, MD | Written by Ana Aleksic, MSc (Pharmacy) | Last updated:
hydrogen water health

Hydrogen water is simply water that contains hydrogen molecules. Allegedly, these hydrogen molecules act as antioxidants. Manufacturers claim that hydrogen added to water helps neutralize oxygen free radicals that contribute to diseases, inflammation, and aging. Sound too good to be true? You’re on the right track. Read on to learn about some real science behind the hydrogen water hype.

What is Hydrogen Water?

Is There Any Good Science Behind it?

As we outline studies in this post, we’ll point out various study flaws.

The first question we should ask ourselves is whether there is any good science behind hydrogen water.

Most of the time, the answer is no. This became evident once we drilled down into methodological flaws, scientific inconsistencies, author credentials, and financial incentives. A combination of these factors is a recipe for bad science.

Certain research findings behind hydrogen water have never been replicated. Some studies were funded by hydrogen water manufacturers or performed by the same groups of people in Japan who had conflicts of interest.

Additionally, several clinical trials on hydrogen water didn’t include a control group drinking regular water. Thus, any potential benefit could simply be due to drinking enough water, which is known to be good for health.

The majority of trials that didn’t suffer from glaring flaws like these still had a small sample size. It’s impossible to draw any reliable conclusions from a study on 10 or 20 people, for example.

There are some noteworthy exceptions.

A couple of unbiased studies have been published. We hope to see more of them in the future, which would determine the efficacy and safety of hydrogen water in humans.

Currently, there is insufficient evidence to support any of the purported benefits of hydrogen water.

How Some Manufacturers Violate FDA Regulations

Lacking proper evidence, some manufacturers take the existing bad science as proof, hype findings, and sell hydrogen water products of unknown quality.

Alkaline water (and alkaline water machines) have not been approved by the FDA for medical use. Alkaline water is classified as a dietary supplement. Supplements generally lack solid clinical research. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing.

The FDA recently issued warnings to a couple of alkaline water manufacturers for making therapeutic claims of their products.

These manufacturers falsely claimed that alkaline water can cure, mitigate, treat, or prevent disease. One manufacturer (ALKAZONE ANTIOXIDANT WATER) claimed that their alkaline water can “have a positive effect upon the health of patients suffering from severe illnesses.” [1]

To make matters worse, the same manufacturer failed to comply with Current Good Manufacturing Practice (CGMP). Their water was not properly tested, its purity wasn’t determined, and the instruments used to produce it weren’t controlled. This means that their alkaline water may have been adulterated with unsafe compounds [1].

This doesn’t mean that all hydrogen water manufacturers are at fault. But consumers need to do their research and buy from a reputable source if they decide to drink hydrogen water.

The Chemistry of Hydrogen

Hydrogen (H2) is the most abundant molecule in the universe. It is an odorless, colorless, and tasteless gas.

Hydrogen is the smallest existent gas molecule. Because of this unique property, some researchers hypothesized that it might penetrate into organs and cells in the body (including the brain). It’s claimed to have antioxidant, anti-inflammatory, and anti-allergy activity, but no clinical trials attest to these purported effects or to its penetrating capacity [2].

Research Timeline

Hydrogen was used for the first time in humans in the early 90s. It was given as a gas to three divers, hypothesized to help them overcome the effects of deep-sea diving (high pressure on the brain) [3, 4].

In 2007, a team in Japan announced that inhaled hydrogen gas may act as an antioxidant. The authors hypothesized that hydrogen might protect the brain from free radicals, but their theory was never proven. Nonetheless, this study sparked interest worldwide. Companies caught on and funded the majority of hydrogen research in later years [5, 2].

Hydrogen water is water with added hydrogen molecules. Manufacturers formulated it as the most practical and easy way to offer hydrogen to the public. But it’s not the only way – studies suggest that hydrogen can also be inhaled, injected, or absorbed through a bath. These methods of application are being researched in emergency and critical care medicine in China [5].

Since the initial Japanese study, the effects of hydrogen have been researched in 63 diseases. But most of the research was done in experimental animals while proper clinical trials are still lacking [3].

Hydrogen molecules are small and odorless. Research on hydrogen water is in the early stages. Clinical studies were flawed and proper trials are still lacking.



The following effects were found in cells, animals or pilot trials in humans:

  • Claimed to be “neuroprotective” and “antioxidant” and “anti-inflammatory”
  • Likely safe, if properly manufactured


  • Clinical research biased and flawed
  • Effectiveness unknown
  • Side effects unknown
  • Benefits hyped
  • Products often misbranded
  • Risk of contamination

Purported Health Benefits of Hydrogen Water

Insufficient Evidence for:

The following purported benefits are only supported by limited, low-quality clinical studies.

There is insufficient evidence to support the use of hydrogen water for any of the below-listed uses.

Remember to speak with a doctor before drinking large amounts of hydrogen water. Hydrogen water should never be used as a replacement for approved medical therapies.

Antioxidant and Brain-Protective Effects

Scientists first investigated the effects of molecular hydrogen (H2) reactive oxygen species (ROS) damage in cell culture. One study in rats suggested that inhaled hydrogen can reach the brain, but the effects of hydrogen water on antioxidant status and brain health in humans are unknown [6].

In the first pilot study of 38 stroke patients, a hydrogen solution (IV) was safe. This study was open-label, meaning that both the investigators and patients knew what was being administered. Also, this study was not randomized. Therefore, various biases could’ve been introduced [7].

In another small study of 17 patients with Parkinson’s disease, those who drank 1 L of hydrogen water as an add-on to conventional treatment (levodopa) had improved symptoms. Those who drank regular “placebo” water experienced a worsening. The authors state that these effects were significant, but it’s impossible to draw reliable conclusions from such a small sample [8].

A larger follow-up trial is currently underway [9].

Additionally, the last author stated on the first publication, N. Hattori, has served as an advisory board member for various pharmaceutical companies; he also received personal compensation for attending advisory board meetings. His involvement with hydrogen water companies was not mentioned [8].

Properly-powered studies are still lacking. Additionally, no study has looked at the effect of hydrogen water alone on Parkinson’s Disease.

Scientists investigated the effects of hydrogen water on oxidative stress and Parkinson’s Disease prevention in rats. They suggested that lower doses were more effective in lab animals. Rats who drank hydrogen water did better than those who constantly received higher amounts of hydrogen intravenously. These findings can’t be extrapolated to humans [10].

Hydrogen water seemed to prevent cognitive, learning, and memory problems in mice under stress. The researchers posited that it might act as an antioxidant. One team is looking at the effects of hydrogen and stress on the brain’s memory hub – the hippocampus. These mechanisms remain unexplored in humans [11].

Hydrogen water is hypothesized to protect the brain from free-radical damage, but proper clinical evidence is lacking.


In one pilot study, 20 patients with early rheumatoid arthritis drank 0.5 L/day of hydrogen water for 4 weeks. The paper states that all patients experienced symptom improvement and that 20% became symptom-free. The authors declared that they had no conflict of interest, but the sample size was too small to draw reliable conclusions [12, 13].

Animal research also investigated whether molecular hydrogen (H2) has anti-inflammatory effects. Large-scale clinical trials are needed [14, 15].

Muscle Fatigue and Weakness

In an experiment with 10 young athletes, drinking hydrogen water reduced lactic acid build-up during heavy exercise and decreased muscle fatigue. The control was regular water and the participants were examined in a crossover double-blind manner l [16].

Similar to the previously analyzed study, the authors had no declared conflict of interest but the study was too small to be meaningful [16].

In another study, drinking 2 L of hydrogen water daily helped 8 cyclists power through sprints with more energy and less exhaustion. This study was conducted in Italy and the investigators were not blinded. Also, there was no wash-out period between hydrogen and normal water, and each water was given for only two weeks. Conflicts of interest were not specified in this study [17].

In a study on mice with a serious muscle-wasting disease (Duchenne muscular dystrophy or DMD), hydrogen water prevented abnormal weight gain and increased the production of the antioxidant glutathione peroxidase [18].

It’s important to remember that animal findings can’t tell us anything about the effects of a substance in humans. Many compounds have an effect in animals but fail to pass human trials. Hydrogen water hasn’t been investigated in people with DMD

There is insufficient evidence about the effects of hydrogen water on muscle recovery and physical performance.

Metabolic Syndrome & Type 2 Diabetes

There is not enough evidence to support the use of hydrogen water for metabolic syndrome or diabetes.

In a pilot study with patients prone to metabolic syndrome, drinking hydrogen water (1.5 – 2 L/day) for 8 weeks increased HDL-cholesterol and decreased total cholesterol [19].

A major limitation is that this study was an open-label trial on only 20 people. Secondly, three out of five authors were associated with KGK Synergize, a contract research organization. The study was conducted at their headquarters in London, ON, Canada. Conflicts of interest were not mentioned in the full-text of the publication.

In another study, drinking hydrogen water (900 mL daily for 8 weeks) decreased cholesterol and improved glucose tolerance and insulin resistance in a study of 36 patients with type 2 diabetes or prediabetes (impaired glucose tolerance). Pure water was used in the placebo group and this study was randomized and double-blinded [20].

Drinking sufficient amounts of regular water alone is known to be beneficial in people with metabolic syndrome and diabetes; low water intake is linked to high blood sugar [21].

Some scientists are studying the effects of hydrogen water on energy use, glucose, insulin, triglycerides, and fatty liver in mice with type 2 diabetes, obesity, and those fed a high-fat diet. It also boosted energy use and reduced levels of [22].

Other research teams suggested that, in rats, hydrogen water might prevent the hardening of the arteries or atherosclerosis. This has never been investigated in humans [23].

It’s unknown whether hydrogen water can improve metabolism or blood sugar control since proper clinical trials are lacking.

Mitochondrial Health

One scientific review suggested that hydrogen water may protect the mitochondria, the body’s energy powerhouse, according to studies of 41 people with muscle diseases. They drank 0.5-1 L of hydrogen water per day. However, a double-blinded trial had less prominent effect than an open-label trial [24].

Some researchers hypothesize that drinking hydrogen water might stimulate energy metabolism based on studies in mice. This hypothesis remains unproven [25].

Side Effects of Chemotherapy and Radiation

There is not enough data to determine the safety and efficacy of hydrogen water in people undergoing radiotherapy and/or chemotherapy. Proper clinical trials are lacking.

In one study of 49 patients undergoing radiation therapy for liver cancer, drinking hydrogen water (1.5 – 2 L/day) improved the patients’ quality of life and appetite. The authors declared no competing interests. They suggested that hydrogen water might also reduce oxidative stress and damage from radiation, but this has not been proven [26].

Some researchers think that hydrogen water may increase survival, reduce kidney damage, and prevent weight loss from a chemotherapy drug (cisplatin) in mice. This has not been investigated in humans [27].

Skin Health

Hydrogen water given through an IV solution improved skin health in 4 patients with skin redness and inflammation, and pain. They state that skin redness went away after a couple of days of treatment and did not come back. However, it’s impossible to make any health-related claims based on a study on 4 people [28].

In another extremely small study of 6 people, bathing in hydrogen water for 3 months seemed to reduce skin wrinkles Hydrogen water was also said to boost collagen production, reduce UV damage, and act as an antioxidant in skin cells. The authors said that warm hydrogen-infused baths might be a pleasant anti-aging practice, but proper clinical data are lacking to support their claims [29].

Some scientists think that hydrogen water infusions and baths may soothe and rejuvenate the skin, but solid clinical data are lacking.

Wound Healing

In one small study, hydrogen water intake via tube feeding in 22 elderly patients reduced the wound size of pressure ulcers and enhanced recovery. Larger, better-designed trials are needed [30].

Liver Health

In 60 patients with Hepatitis B, hydrogen water added to regular treatment reduced oxidative stress, compared to the group who only received regular treatment. Adding hydrogen water did not appear to improve liver function better than conventional treatment alone. These findings have not been replicated [31].

Some scientists suggest hydrogen might suppress liver scarring in mice by protecting liver cells from free-radical damage. This hasn’t been investigated in humans [32].

Oral Health

Drinking hydrogen water 4-5 times daily improved gum health in 13 patients with inflamed gums after 8 weeks. It also seemed to increase blood antioxidants and the effects of non-surgical treatment. No conflicts of interest were declared. However, this study was small and short and its findings were not replicated. Further research is needed [33].

Some researchers are investigating hydrogen water against bacteria that cause gum disease and cavities in cell culture [34].

Lacking Evidence (Animal and Cellular Research)

No clinical evidence supports the use of hydrogen water for any of the conditions listed in this section.

Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.

Mood Disorders

There is no evidence to support the use of hydrogen water for mood problems.

Some scientists are exploring whether hydrogen water can restore the growth of brain cells and reverse stress-induced damage in mice. According to one theory, the birth of new brain cells is linked with overcoming depression (with antidepressants or otherwise) [11, 35].

However, no studies have examined the effects of hydrogen water on depression and other mood disorders in humans


The effects of hydrogen water on weight control in humans are unknown.

Long-term drinking of hydrogen water seemed to help rats lose body fat and weight in one study. The authors hypothesized it increased burning fats and sugars for energy, suggesting that it may have similar effects to calorie restriction [22].

However, this theory remains unproven. Many supposed weight-loss-boosting substances investigated in animals turn out to be ineffective in later human trials.

Alkalizing Effects

Metabolic acidosis is when the blood becomes more acidic, which can happen from intense exercise. In 52 active men, drinking 2 L of hydrogen water daily increased the blood pH before and after exercise after 2 weeks with no side effects. However, whether or not increasing blood pH (“alkalizing the body”) is beneficial or not hasn’t been proven [36].


Drinking hydrogen water stopped immediate-type allergic reactions in mice. These occur within a couple of minutes and are more characteristic of Th2 dominance, according to some insufficiently-validated theories. In mice with eczema, hydrogen water improved symptoms, supposedly by suppressing inflammation (balancing Th1/ Th2 responses) [37, 38].

The effects of hydrogen water on allergies and Th1/Th2 immune responses in humans are unknown.


Hydrogen-rich water prevented kidney damage in rats. Scientists posit it might reduce oxidative stress, improve kidney blood flow and function (lowering creatinine and BUN) [39].

Hydrogen added to the dialysis solution reduced inflammation and high blood pressure in 21 patients on dialysis because of kidney failure [40].

Much more research is needed before the effectiveness and safety of various hydrogen formulations on kidney health are determined.

Various Organs

The effects of alkaline water on bladder, heart, eye, ear, lung, and gut health in humans are completely unknown.

In rats with a blockage in the bladder, drinking hydrogen water reduced bladder volume by neutralizing oxidative stress. The authors suggested that it also may have improved the responsiveness of bladder muscles [41].

In diabetic mice, hydrogen water seemed to improve heart health [42].

Hydrogen-loaded eye drops aided the recovery of eye injuries in rats. The authors hypothesized that it protected the nerves in the eye by its antioxidant action [43].

A hydrogen solution reduced detrimental blood vessel growth in mice with eye injuries from chemicals. Some scientists think that hydrogen solutions should be further researched as a first-aid rinse to prevent eye damage from chemical burns, but clinical data are lacking [44].

Scientists believe that hearing loss often results from oxidative damage (due to aging, noise, or drugs). They are exploring the effects of molecular hydrogen on the survival of damaged ear cells [45].

In guinea pigs, hydrogen water prevented the death of sound receptors after noise exposure. Some researchers think hydrogen water research should focus on its effects on hearing loss caused by noise or other types of oxidative stress [46, 47, 48].

Gut & Lung Health

Hydrogen-rich water prevented damage to the stomach lining in rats. The researchers hypothesized antioxidant and anti-inflammatory effects [49, 50].

Rats who drank hydrogen water appeared to be protected against lung tissue injury (possibly by affecting NF-κB and oxidative stress) [51].

Radiation Side Effects

Some scientists suspect that molecular hydrogen may have radioprotective properties. Giving mice hydrogen water before radiation seemed to increase their survival and prevent heart damage [52].

One group also examined the effects of hydrogen on the survival of white blood cells exposed to radiation [53].


Drinking hydrogen water appeared to reduce neuropathic pain in mice. Clinical trials have not yet investigated the effectiveness of hydrogen water in people with neuropathic pain [54].


Some brands state that drinking hydrogen water may increase longevity in humans, but these claims are unsubstantiated.

According to one unproven theory, molecular hydrogen might protect the DNA and mitochondria from oxidative damage, which would theoretically help slow down or reverse the aging process. But scientists only investigated hydrogen in cellular studies, leaving us without any clue about its alleged anti-aging potential [55, 56].

Cellular research looked at the following pathways or types of cells:

  • Survival of stem cells exposed to oxidative stress [57]
  • Oxidative stress and aging [58]

Therefore, no evidence about the anti-aging effects of hydrogen water exists.

Potential Mechanism of Action

The mechanism of action of hydrogen is unknown and poorly researched.

Some scientists believe it has the unique capability of entering cells and cell components (organelles), such as the mitochondria and nucleus (where DNA is stored). Some say that other molecules cannot penetrate this deep into cells. However, this hypothesis has never been proven [2, 6].

The effects of hydrogen water on the following pathways have been researched in animals and cells:

These proposed mechanisms have not been confirmed or investigated in humans.

Safety, Dosage, Side effects

Side Effects

The side effects and safety of molecular hydrogen (H2) are unknown, given the lack of well-designed clinical studies. Consult your doctor about potential side effects, based on your health condition and possible drug or supplement interactions.

Some scientists believe it’s not toxic, but proper clinical data are lacking. Some research teams have proposed that smaller amounts of molecular hydrogen may have stronger effects than very high amounts, but this has never been confirmed in human trials [55].

The long-term risks of hydrogen water will remain unknown until additional studies are carried out.


Given the lack of effectiveness and safety data, hydrogen water dosage can’t be established.

In most clinical studies, people drank 0.5-2 L of hydrogen water daily. Some scientists say that after drinking hydrogen water, about 40% of the H2 is absorbed by the body. This hasn’t been clinically verified [8].

Therefore, no dosing guidelines can be made at this point. Additionally, the exact hydrogen amounts in many products on the market are unclear. Some products may even be contaminated with harmful compounds.

Also, molecular hydrogen is a gas and it evaporates quickly. So if you add hydrogen to water, it will be gone within a few minutes.

Limitations and Caveats

Most studies were conducted only by a couple of research teams, mostly in Japan.

Health benefits of hydrogen water need to be investigated in larger-scale clinical trials.

Since drinking sufficient amounts of regular water is essential for good health, all clinical studies should use equal amounts of regular water as a control group, and this was not always the case in these studies.

Additionally, some health benefits were only researched on animals or cells. These can’t be extrapolated to humans.

Many hydrogen products are sold in the form of pills, but the effects of these products are even less clear.

Where to Get Hydrogen Water

As hydrogen water is becoming more popular, you can now find:

  • Hydrogen water in a bottle (around $3 per bottle)
  • Hydrogen tablets to dissolve in water yourself
  • Small portable hydrogen water makers
  • More sophisticated hydrogen water generators for your home

Another reason for skepticism is the quality of expensive products on the market. Are they worth it? It’s unknown how these products compare to the type of hydrogen water used in research studies.

As mentioned, some manufacturers violated several FDA guidelines (labeling, contamination, quality control, and other) [1].

This puts the quality of all products on the market into question and stresses that consumers need to pay special attention to product quality certificates. If you decide to try hydrogen water, do your research and make sure to get it from a reputable manufacturer.

Additionally, some people think that taking lactulose is a way to naturally increase hydrogen in the body, but there’s no clinical evidence to back them up.

Humans can’t produce molecular hydrogen. However, some limited research suggests that our gut bacteria can when we take in various fibers such as lactulose. Gut bacteria might be able to create a large amount of hydrogen from lactulose, but this also comes with side effects such as gas and bloating. Lactulose increased hydrogen in the body similarly to hydrogen water in a study of 65 people [10].

The available products with molecular hydrogen are often expensive and have questionable quality.


Hydrogen water is said to supply pure hydrogen. Companies claim it improves brain health, metabolism, and physical performance. However, there is insufficient data to support any of the purported health benefits of hydrogen water.

Additionally, products available on the market are of questionable quality. Some violate FDA regulations by making unsubstantiated health claims while selling potentially-contaminated water.

Long-term safety studies on hydrogen water are lacking. A dosage of 0.5-2 L daily was used in clinical trials.

All in all, the available research on hydrogen water has massive limitations, and it’s far from conclusive. Some evidence suggests that drinking properly-manufactured hydrogen water is probably not dangerous, but we don’t yet know if it’s any good either.

Drinking enough regular water is proven to be beneficial for health, unlike hydrogen water.

Until unbiased, high-quality research comes out, the use of hydrogen water remains unproven.

About the Author

Ana Aleksic

Ana Aleksic

MSc (Pharmacy)
Ana received her MS in Pharmacy from the University of Belgrade.
Ana has many years of experience in clinical research and health advising. She loves communicating science and empowering people to achieve their optimal health. Ana spent years working with patients who suffer from various mental health issues and chronic health problems. She is a strong advocate of integrating scientific knowledge and holistic medicine.


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