What is the downside of xylitol? Exploring the potential health risks and side effects

October 6, 2025 •

3 min read

Recent research from the Cleveland Clinic linked high levels of xylitol to an increased risk of heart attack and stroke in people. While celebrated for its dental benefits and low glycemic index, understanding the potential downsides of xylitol, a common sugar alcohol, is crucial for those managing their health, especially individuals with pre-existing conditions.

Quick Summary

Xylitol, a popular sugar alcohol, presents potential health risks beyond its common gastrointestinal side effects. Recent studies indicate a possible link to an increased risk of cardiovascular events, particularly for vulnerable individuals. Extreme toxicity to dogs is another major concern, demanding careful handling and storage of products containing this sweetener. It is important to consider these factors, along with personal tolerance, when deciding on its use.

Key Points

Cardiovascular Risk: Recent studies have linked high blood levels of xylitol to an increased risk of heart attack and stroke due to enhanced blood clotting.
Digestive Issues: Excessive consumption can cause bloating, gas, cramps, and diarrhea, as xylitol is poorly absorbed and fermented by gut bacteria.
Extreme Pet Toxicity: Xylitol is highly toxic to dogs, causing a rapid, dangerous drop in blood sugar (hypoglycemia) and potential liver failure.
Comparison to Other Sweeteners: Xylitol is more likely to cause digestive upset than erythritol, and both have been associated with potential cardiovascular risks in recent research.
Liver and Gut Effects: Emerging evidence suggests potential links to liver fat accumulation with high intake and a complex, not fully understood impact on the gut microbiome.
Personal Tolerance: The tolerable dose of xylitol varies significantly between individuals, with some experiencing side effects at lower levels than others.
Check Labels Carefully: Xylitol is hidden in many "sugar-free" products, including candies, gums, and even some peanut butters, making label-checking essential for risk management.

The Surprising Link to Cardiovascular Risk

Recent research has raised concerns about the cardiovascular safety of xylitol. A 2024 study, including researchers from the Cleveland Clinic, found an association between high levels of xylitol in the blood and an increased risk of heart attack, stroke, and death. This study suggested that xylitol could enhance platelet activity, potentially making blood more prone to clotting. Healthy volunteers who consumed a xylitol-sweetened drink showed increased platelet clottability for several hours. While more research is needed, these findings suggest a potential risk, particularly for those already susceptible to cardiovascular issues.

Gastrointestinal Distress and Osmotic Effects

Xylitol, like other sugar alcohols, can cause digestive problems when consumed in large amounts. Because it's not fully absorbed in the small intestine, it travels to the large intestine where gut bacteria ferment it, producing gas. This unabsorbed xylitol also has an osmotic effect, drawing water into the intestines and causing a laxative effect. Individuals with sensitive digestive systems, such as those with IBS, may be particularly affected. While some people can build tolerance by starting with small doses, exceeding about 50 grams daily can lead to issues for many.

Life-Threatening Toxicity in Dogs

Xylitol is extremely toxic and potentially fatal to dogs, even in small amounts. When ingested, it's rapidly absorbed, causing a powerful release of insulin and a dangerous drop in blood sugar (hypoglycemia). This can occur within 10-60 minutes and is life-threatening. Higher doses can also cause severe liver failure. Symptoms include vomiting, lethargy, loss of coordination, tremors, and seizures. Pet owners should check labels and keep xylitol-containing products like sugar-free gum, candy, and some peanut butters away from dogs.

Comparing Xylitol with Other Sweeteners

Comparing xylitol with alternatives like erythritol can help consumers make informed choices.


Feature	Xylitol	Erythritol
Digestive Issues	Higher potential for bloating, gas, and diarrhea, especially at higher doses, due to poor absorption and fermentation.	Generally causes fewer digestive issues, as most of it (around 90%) is absorbed before it reaches the large intestine.
Caloric Content	2.4 calories per gram, roughly 40% fewer than sugar.	0.2 calories per gram, very close to zero.
Sweetness	Has the same sweetness as table sugar.	About 70% as sweet as table sugar.
Cardiovascular Risk	Recent observational studies suggest a link to increased blood clotting and risk of heart attack and stroke.	Recent studies also suggest a potential link to increased blood clotting, similar to xylitol.
Effect on Blood Sugar	Has a minimal but small impact on blood glucose and insulin levels.	Has virtually no effect on blood glucose or insulin levels.

Potential Effects on Liver and Gut Microbiome

Some research suggests that high consumption of sugar alcohols, including xylitol, might be linked to increased fat accumulation in the liver, a condition called non-alcoholic fatty liver disease (NAFLD). This raises questions about its long-term effects on liver health. Xylitol's partial absorption means it also interacts with gut bacteria. It can act as a prebiotic, but high intake can alter gut microbiota composition and may even delay diarrhea healing. The long-term effects on the gut microbiome are still being studied.

Conclusion

While xylitol offers benefits, particularly for dental health, its drawbacks are significant. The potential link to increased cardiovascular risk, especially for vulnerable individuals, is a recent concern. Gastrointestinal side effects are common with higher consumption. Most importantly, its extreme toxicity to dogs requires careful handling of products containing it. When using xylitol, start with small amounts to gauge personal tolerance and always check product labels, especially if you have a dog. Consult a healthcare provider for personalized dietary advice. For dental health, the frequency and duration of use are key. Learn more at the Cleveland Clinic.

Frequently Asked Questions

The most concerning recent finding is the potential link between high blood levels of xylitol and an increased risk of serious cardiovascular events, such as heart attack and stroke, due to its effect on blood clotting.

Yes, consuming too much xylitol can lead to gastrointestinal issues like bloating, gas, stomach cramps, and diarrhea. This is because it is poorly absorbed and fermented by bacteria in the large intestine.

In dogs, xylitol causes a rapid release of insulin, leading to a severe and potentially fatal drop in blood sugar (hypoglycemia). Higher doses can also cause irreversible liver failure.

While tolerance varies, many adults can tolerate up to 50 grams per day without significant gastrointestinal issues after building up a tolerance. However, given the recent cardiovascular concerns, careful monitoring and moderation are advised, particularly for at-risk individuals.

Initial symptoms include vomiting, lethargy, decreased activity, staggering, and incoordination. Because these symptoms can progress quickly, immediate veterinary care is crucial if xylitol ingestion is suspected.

Erythritol is often better tolerated digestively than xylitol because it is better absorbed. However, recent research also found a potential link between erythritol and increased blood clotting, so both should be used in moderation.

Yes, because it is partially fermented in the large intestine, xylitol can influence gut bacteria. While it can promote beneficial bacteria growth, it can also cause temporary shifts and digestive upset, and its long-term effects on the microbiome are still under investigation.

Preliminary research suggests a link between excessive sugar alcohol consumption and increased fat accumulation in the liver, raising concerns about potential long-term effects on liver health.