Even large amounts of xylitol are harmless to children and adults. However, you shouldn’t take more than 3 to 4 teaspoons (15 to 20 g) of xylitol per day in the beginning because otherwise it can have a laxative effect. Gradually increase the dosage as needed until your body gets used to larger amounts, which takes a few days. We recommend no more than 100 g of xylitol per day for adults, and up to 50 g per day for children up to 12 years of age. Xylitol is less suitable for infants under 12 months because they cannot yet optimally metabolize it. Children under 3 years shouldn't consume xylitol daily because there is not enough data yet about the long-term effects in young children.
People with a fructose intolerance should only take xylitol in very small doses at first. Most of them don’t have a problem with xylitol, but some do. Erythritol is the better choice for those who have similar problems with fructose and xylitol.
Xylitol is dangerous to some animals (including dogs, rabbits, and goats). It can cause them serious liver damage because they are missing an important enzyme in the liver which helps break down xylitol. Xylitol also provokes an insulin secretion in these animals, causing excessively low blood sugar. Even low doses of xylitol (5 g) can be lethal to dogs. A sugar solution can help as a first aid, but veterinary attention is required if xylitol poisoning has occurred..
For cats, it is recommended to add xylitol to their drinking water in order to reduce plaque and tartar.
Humans do not have metabolic problems with xylitol, even if they are intolerant to it.