Does toothpaste break a fast?

Toothpaste often tastes sweet. One common fluoride toothpaste lists sorbitol, a sugar alcohol, and sodium saccharin among its inactive ingredients. Neither is table sugar, and you spit the paste out after brushing.

A pea-sized amount of toothpaste weighs about 0.25 g. As a worked example, suppose all of it were sorbitol and you swallowed every bit. Food labelling counts sugar alcohols at 2.4 kcal per gram, so 0.25 g would give about 0.6 kcal. That is far below the common 50-calorie rule of thumb, which is not an official limit.

On the four goals this site uses to sort answers, brushing is safe for weight loss, blood sugar, autophagy and gut rest. The sweet taste is brief and leaves your mouth when you spit. Your stomach and gut get nothing to digest. There is no reason to skip brushing in a fasting window, including first thing in the morning.

Brush as normal while you fast, twice a day with fluoride toothpaste. Spit out the excess and try not to rinse with water, so the fluoride stays on your teeth longer. If you use mouthwash too, use it at a different time of day, as rinsing straight after brushing washes that fluoride away.

Children are the group to watch. Under-3s need only a smear the size of a grain of rice, and 3 to 6-year-olds no more than a pea-sized amount. If anyone swallows more than the amount used for brushing, get medical help straight away.