Myth busting: Fairy dishwashing tablets do not cause "leaky gut”

This article will respond to some content online suggesting that using household dishwasher detergents can lead to “leaky gut”. We would like to reassure consumers that this is misinformation and that using Fairy dishwashing tablets does not cause "leaky gut," gut inflammation, or intestinal barrier damage.

This article explains how the study behind the myth (Ogulur et al., 2023, Journal of Allergy and Clinical Immunology) has been taken out of context, causing unsubstantiated claims to spread online. The myth has also been debunked by independent experts at Michigan State University’s Center for Research on Ingredient Safety and by Wirecutter’s dishwashing expert Andrea Barnes.

The machines used in the study: Commercial vs. domestic appliances

The study focused primarily on the effects of product concentrations found in professional (or commercial) dishwashers. These powerful machines are often used in hospitals or restaurants and can complete wash cycles in minutes, so they function very differently from household dishwashers and are not relevant to domestic use. Even so, for professional dishwashers, the conclusions would not support a link to “leaky gut”.

Only one of the tests was done directly with solution remaining at the end of a household dishwasher cycle and it found no effect from the household dishwasher use under the tested conditions.

The products tested in the study: commercial rinse aids vs. household products

While the online videos focus on consumer dishwashing products, the only products shown to have any effect in this study were professional rinse aids at a concentration predicted to be found at the end of professional dishwasher use. The three household dishwasher detergents tested showed no effect on the gut under the tested conditions. Even so, conclusions for rinse aid would not support such claims for the additional reasons explained below.

The concentrations used in the study: laboratory extremes vs. everyday use

The study’s dosages are unrealistically higher compared with those that could be expected in common consumer-use situations, so the conclusions are not realistic or relevant to the safety of household detergents when used as intended.

CRIS suggests that the dilution ratio in one experiment was more than 300 times more concentrated than what we’d be exposed to in a typical use setting. Even the highest dilution factor they explored was 2 times more concentrated than a typical use case.

For comparison, the New York Times article on this topic suggests that, irrespective of whether the dishwasher is commercial or residential, the rinse aid dilutions used in this study do not reflect a manufacturer’s recommended use, according to Joseph Zagorski, a toxicologist and associate professor at the Center for Research on Ingredient Safety, a toxicology research center at Michigan State University. “When used as directed, with the proper dilution, alcohol ethoxylates are considered safe for use. The referenced paper uses dilutions that are outside of the manufacturer’s requirements,” said Zagorski.x

According to the New York Times article, the study did not detect detergent residue on dishes washed in typical household dishwashers. The reporter even concludes and says: I am happy to say that based on what we know now, I continue to use rinse aid without worry.

Interpreting effects seen at very high concentrations as evidence that a substance is unsafe under normal conditions also overlooks a basic principle of toxicology: the dose matters. For example, benzaldehyde, a fragrance material that is also naturally present in almonds, is classified as a hazard. However, a human would need to eat 166,000 almonds or apply 276,660 sprays of benzaldehyde every day for the rest of their life to be exposed to objective risk (Joshi et al., 2026, Regulatory Toxicology and Pharmacology). This is why normal daily consumption of almonds, or the use of benzaldehyde in a fragrance, does not pose an objective risk and is considered safe. It is also why it is scientifically incorrect to suggest that an ingredient or product is unsafe simply because the ingredient produced an effect when tested at an unrealistically high dose.

The in vitro testing used in the study: lab cells vs. human bodies

The study itself states: “there is a lack of in vivo data in the present study. Further studies are needed to demonstrate whether similar mechanisms are involved in humans.”

Regulatory standards and chemical safety

Products sold in the UK and EU are subject to some of the world's most rigorous chemical safety frameworks, including, but not limited to, REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals), the Detergents Regulation (EU) 2026/405, and CLP (Classification, Labelling and Packaging). See here for the EU regulations that Fairy dishwashing products need to meet. In addition, Fairy products are subject to thorough product stewardship programs and ingredient-specific safety assessments to ensure they are safe for consumers when used as intended. See here for more information on how Fairy ensures its products are safe.

What to look for in videos that make sensational safety claims

CRIS provides clear recommendations on what to look for in videos that make sensational claims about the safety of products, foods, or cosmetic ingredients. There are two important things to consider:

1. Creator’s objective: Is the video from an account seeking to sell a product, course, or lifestyle? If so, understand that the information will be curated to fit the creator’s objective. It may not represent the actual risk.
2. Creator’s source material: Does the source material make the same claims as the content creator? Unfortunately, headlines of all sorts, including academic papers, are intentionally provocative to catch attention. You must look deeply at the source to see if it’s relevant to the human experience.