Xylitol
Xylitol is a sugar substitute that is safe for most people in food-sized amounts but causes wind and diarrhoea at high doses, and it is extremely toxic to dogs. The best-supported use is preventing ear infections in healthy children at daycare (a Cochrane review found risk fell from about 30% to 22%, moderate-quality evidence); for tooth decay the Cochrane evidence is only low quality. A 2024 Cleveland Clinic study linked higher blood xylitol to more heart attacks and strokes and made platelets stickier, a signal that needs confirming, not proof of harm from normal use.
At a glance
Last reviewed 30 September 2026What it's used for
Evidence is rated per use. The same ingredient can be strong for one thing and traditional for another.
| Use | Evidence | What the research shows |
|---|---|---|
| Preventing ear infections (acute otitis media) in children | Moderate | A Cochrane review of 5 trials (3,405 children up to 12 years) found, in three trials of 1,826 healthy Finnish daycare children, moderate-quality evidence that xylitol in any form cut the risk of ear infection from 30% to about 22% (risk ratio 0.75, 95% CI 0.65 to 0.88). It did not work in healthy children during a respiratory infection (RR 1.13, 0.83 to 1.53) or in otitis-prone children (RR 0.90, 0.67 to 1.21). The authors note that most of the data came from one research group.2 |
| Preventing tooth decay (dental caries) | Limited | A Cochrane review of 10 trials (5,903 people) found low-quality evidence that a fluoride toothpaste with 10% xylitol reduced caries by 13% over 2.5 to 3 years compared with fluoride-only toothpaste (95% CI 8% to 18%). That result came from two studies by the same authors in one population, and seven of the 10 trials were at high risk of bias. One small study found xylitol syrup (8 g a day) cut caries by 58% in infants compared with a low dose. For gum, lozenges, tablets and wipes the confidence intervals included no effect, and for adults there was one study; the authors said the evidence was insufficient.1 |
| Cardiovascular risk (harm signal, blood level) | Limited | Not a use, a warning signal. In 2,149 people having cardiac evaluation, those in the top third of fasting blood xylitol had a higher risk of heart attack, stroke or death over 3 years (adjusted hazard ratio 1.57, 95% CI 1.12 to 2.21). In platelet and animal experiments xylitol made platelets more reactive and promoted clots, and in 10 healthy volunteers a xylitol-sweetened drink raised blood levels and platelet responsiveness. It is observational in patients already being investigated for heart disease, the intervention was tiny and the body also makes xylitol; the authors call for cardiovascular safety studies, not for people to stop.3 |
| Gut side effects at high doses (harm signal) | Moderate | Xylitol is poorly absorbed, so large amounts cause diarrhoea. In 55 healthy adults the largest dose without transitory diarrhoea was 0.37 g per kg body weight for men and 0.42 g per kg for women (about 26 g for a 70 kg man), tested from 10 to 50 g taken in water. In a 3-month trial of 120 children aged 6 to 36 months, 5 g three times a day or 7.5 g once daily gave rates of gas and diarrhoea similar to placebo.4,5 |
How much
Ranges below are what studies used and what supplements commonly contain. They are not a recommendation for you. Start at the low end.
How people take it
Safety
Who should avoid
- Dogs — keep all xylitol products out of reach; call a vet at once if eaten
- People with heart disease or clotting risk — ask your clinician given the 2024 signal
- Large amounts at once — wind, bloating and diarrhoea
- Pregnancy and breastfeeding — we found no safety data at supplement doses
Known interactions
Questions people ask
What are the side effects of xylitol?
In people the main one is gut upset: wind, bloating and diarrhoea at high doses, with a threshold of about 0.4 g per kg body weight in healthy adults. A 2024 Cleveland Clinic study linked higher blood xylitol to heart attacks and strokes and to stickier platelets; that is a signal needing more study, not proof. For dogs it is extremely toxic.
Is xylitol toxic to dogs?
Yes. The FDA warns it triggers a rapid insulin release in dogs, causing a dangerous fall in blood sugar within 10 to 60 minutes, and sometimes liver failure and bleeding problems; it may not show for 12 to 24 hours. It is in gum, sugar-free sweets, toothpaste, some peanut butters and some vitamins. Call a vet or animal poison control straight away if a dog has eaten any.
What are the benefits of xylitol?
Moderate-quality evidence says it cuts ear infections in healthy daycare children. For tooth decay, the Cochrane review found only low-quality evidence, mainly for a 10% xylitol fluoride toothpaste in children. It is a sugar substitute rather than a treatment.
What is xylitol used for?
It is used as a sweetener in gum, mints, toothpaste and sugar-free products, and in some syrups. The evidence-backed uses are ear infection prevention in children and, weakly, tooth decay prevention.
Sources
- Systematic review Riley P, Moore D, Ahmed F, Sharif MO, Worthington HV. Xylitol-containing products for preventing dental caries in children and adults. Cochrane Database Syst Rev. 2015.
- Systematic review Azarpazhooh A, Lawrence HP, Shah PS. Xylitol for preventing acute otitis media in children up to 12 years of age. Cochrane Database Syst Rev. 2016.
- Cohort study and experiments Witkowski M, Nemet I, Li XS, et al. Xylitol is prothrombotic and associated with cardiovascular risk. Eur Heart J. 2024.
- Clinical study Oku T, Nakamura S. Threshold for transitory diarrhea induced by ingestion of xylitol and lactitol in young male and female adults. J Nutr Sci Vitaminol (Tokyo). 2007.
- Randomised controlled trial Vernacchio L, Vezina RM, Mitchell AA. Tolerability of oral xylitol solution in young children: implications for otitis media prophylaxis. Int J Pediatr Otorhinolaryngol. 2007.
- Regulator guidance US Food and Drug Administration. Paws Off Xylitol; It's Dangerous for Dogs. FDA Consumer Update.
Last reviewed 30 September 2026 · Next review March 2027 · How we rate evidence
Reader notes
Experiences and questions from readers, read by an editor before they appear. They are personal accounts, not evidence, and are not medical advice.