(updated June 2024)
Over the last few decades, studies on animals and humans have examined the effects of molecular hydrogen-enhanced water. As of 2024, hydrogen-rich water is generally considered safe, with minimal to no side effects. However, some minor side effects have been observed, typically in isolated cases. These minor side effects include:
- Loose stool/diarrhea (0.2% of participants in clinical trials)
- Increased frequency of bowel movements
- Hypoglycemia (reported in one diabetic patient)
- Heartburn (observed in one trial)
- Bloating
- Headache (reported by a few people, especially after initial use)
Despite these isolated cases, many studies, including recent ones in 2024, have shown no side effects. For instance, a 2024 study involving 181 subjects with metabolic syndrome or pre-metabolic syndrome who drank hydrogen-rich water for three months reported no side effects. Similarly, a six-month study in 2021 with volunteers over the age of 70 drinking hydrogen-rich water daily also reported no adverse effects.
Reported Hydrogen Water Negative Side Effects
In 2019, there were 79 human publications that utilized molecular hydrogen therapy, involving a total of 1676 participants. Since then, several other clinical trials have been published with no other reported adverse events. In total, nine potential adverse events have been recorded in a total of seven participants.
Loose Stool/Diarrhea
The only adverse event reported in more than a single participant is loose stool/diarrhea, with four participants reporting events at a frequency of 0.2% in clinical research. Another similar adverse event was reported citing increased frequency of bowel movement. It is important to note that four of these five events were reported in a single trial of only 20 participants, in which a magnesium rod was used. The literature reports virtually no magnesium entering the water, which may or may not be correct.
Increased exhaled hydrogen has been linked to irritable bowel syndrome. Lactose intolerance results from lactose passing to the small intestine, where it is consumed by bacteria, leading to excess hydrogen gas production. This extra gas can cause discomfort, diarrhea, and bloating.
Understanding the relationship between endogenous hydrogen gas production in individuals and the therapeutic effects of exogenous hydrogen gas consumption may be an important factor in determining responders and non-responders.
Hypoglycemia
In a single reported case in a diabetic patient, hydrogen water consumption led to hypoglycemia, which is low blood sugar. This was resolved by lowering the patient’s insulin levels, which is an objective benefit rather than a side effect. Hydrogen therapy has been shown in early clinical research to lower insulin in overweight participants. Drink HRW hydrogen tablets have been shown to improve insulin sensitivity in participants with nonalcoholic fatty liver disease.
Heartburn
Another single report cited potential heartburn in the same trial that saw four of the five gastrointestinal-related issues. This is unlikely to be related to hydrogen gas, as hydrogen water has been shown to improve gastroesophageal reflux disease (GERD) outcomes. A placebo-controlled trial involving 84 participants for 3 months reported no adverse events and significant improvements.
Cardiac Failure
A single report of cardiac failure involved a patient undergoing hydrogen therapy via intravenous hydrogen saline in hospitalised patients recovering from acute ischemic stroke. Cardiac arrest can happen immediately following ischemic stroke due to the death of cardiac and neural myocytes in the post-ischemic stroke brain. It cannot be concluded that hydrogen therapy caused cardiac failure.
Headache
A single incident of headache was reported as part of the open-label metabolic syndrome study that recorded the most adverse events. Headaches are the most prominently reported side effect, occurring in new customers after the first use of hydrogen water. Subsequent use typically sees this issue resolved.
Cancer Patients
The final reported adverse event involved patients with stage III and stage IV cancer, where “minor events” that “spontaneously resolved” were cited without specifying the exact nature. Despite ambiguity, this area of adverse events is of particular interest. Current evidence points to hydrogen being a potentially beneficial adjuvant therapy for various cancer models.
Safety of Molecular Hydrogen
In the absence of data on adverse events, the question becomes, “What do we know about the safety of molecular hydrogen and the side effects of hydrogen water?” Molecular hydrogen is commonly used in deep-sea diving because it is far less narcotic than nitrogen gas or even helium gas. Hydrogen narcosis occurs only at high-pressure levels and exhibits no known long-term damages, toxicity, or side effects. Humans produce up to 12 litres of molecular hydrogen gas per day through bacterial breakdown of carbohydrates in our digestive tracts, indicating a high safety profile for exogenous supplementation.
Contraindications of Hydrogen Water
There are currently no known contraindications of molecular hydrogen concerning either prescribed medications, supplements, or specific disease models. Larger trials are needed to determine whether molecular hydrogen will have any contraindications in specific populations or when administered with any prescribed medications. However, no contraindications have been identified so far.
Conclusion on the Side Effects of Hydrogen Water
At this time, molecular hydrogen appears to have an incredibly high safety profile, although new information could change this perspective. New and larger trials are needed to confirm or clarify the existing information. Additives in the hydrogen water source need to be considered, such as aluminium or magnesium, which have their own potential side effects.
Hydrogen water, while largely safe, has some minor reported side effects, including diarrhoea, increased bowel movements, hypoglycemia, heartburn, bloating, and headaches. Most side effects are mild and temporary, resolving with continued use or simple interventions.
Shop Hydrogen Water Products
For more detailed information and to shop for hydrogen water products, visit Alkaway’s Hydrogen Water Products.
1 http://www.jnmjournal.org/journal/view.html?doi=10.5056/jnm.2010.16.3.299
2 https://www.health.harvard.edu/a_to_z/lactose-intolerance-a-to-z
3 https://pubmed.ncbi.nlm.nih.gov/19486890/
4 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5330822/
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7 https://pubmed.ncbi.nlm.nih.gov/28560519/
8 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5908129/
9 https://medicalgasresearch.biomedcentral.com/articles/10.1186/2045-9912-3-13
10 https://cnjournal.biomedcentral.com/articles/10.1186/s41016-016-0056-1
11 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6779007/
12 https://pubmed.ncbi.nlm.nih.gov/25649854/
13 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6804672/
14 https://pubmed.ncbi.nlm.nih.gov/31011768/
15 https://www.sciencedirect.com/science/article/abs/pii/S0891584918311432?via%3Dihub
16 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6352570/
17 https://pubmed.ncbi.nlm.nih.gov/30970215/
18 https://journals.physiology.org/doi/abs/10.1152/jappl.1994.76.3.1113
19 https://journals.physiology.org/doi/pdf/10.1152/physiologyonline.1988.3.2.72
20 https://www.hindawi.com/journals/omcl/2012/353152/
21 https://www.tandfonline.com/doi/full/10.1586/14737175.2014.915745
22 https://www.rxlist.com/magnesium/supplements.htm#SafetyConcerns
23 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10816294/ (2024)
24 https://www.mdpi.com/2076-3921/13/2/145 (2024)
25 https://www.sciencedirect.com/science/article/abs/pii/S0531556521003569 (2021)
