Cough drops can cause diarrhea, particularly when consumed in large quantities. This digestive side effect is not caused by the active medicinal ingredients intended to soothe a sore throat or suppress a cough. The issue arises from the low-calorie sweeteners used in many popular “sugar-free” lozenges. When consuming multiple drops throughout the day, the cumulative dose of these sweeteners can quickly lead to gastrointestinal distress.
Sugar Alcohols and Gastrointestinal Effects
The primary culprits behind this digestive reaction are sugar alcohols, or polyols, which are used as sugar substitutes in numerous processed foods. These ingredients are popular in sugar-free cough drops because they provide a sweet taste with fewer calories than table sugar. Common examples of these polyols found on ingredient labels include sorbitol, xylitol, mannitol, isomalt, and maltitol.
Sorbitol, for example, offers approximately 60% of the sweetness of sucrose but contains about 35% fewer calories per gram. Because it is less sweet, manufacturers often use a greater amount to match the desired flavor profile of a standard product. This increased quantity of the sugar alcohol contributes directly to the potential for digestive symptoms when several drops are consumed in succession.
These sweeteners are widely used because they do not cause a sudden spike in blood sugar levels, making them beneficial for individuals managing diabetes. They are also non-fermentable by oral bacteria, meaning they do not promote tooth decay as rapidly as regular sugar. Despite these advantages, the chemical structure that provides these benefits is the same structure that causes intestinal upset for many people.
The Mechanism Behind Digestive Distress
These sugar substitutes affect the bowels due to incomplete digestion and the resulting osmotic effect within the digestive tract. Unlike common sugars, these compounds are not well-absorbed by the small intestine because the necessary enzymes are lacking. Consequently, they travel largely intact into the lower digestive tract.
Once they reach the large intestine, these poorly absorbed compounds create a high concentration of dissolved particles in the colon. This triggers an osmotic gradient, pulling excess water from the body’s tissues into the intestinal lumen. The resulting increase in water volume softens the stool and accelerates its transit time, which manifests as diarrhea.
The severity of the reaction is directly related to the amount consumed, known as a dose-dependent effect. While many individuals can tolerate small amounts, consuming too many cough drops can easily exceed the body’s tolerance threshold. For example, consuming more than 20 grams of sorbitol per day is frequently associated with diarrhea, though smaller amounts can cause gas and bloating in sensitive individuals.
When a person is sick, they may consume a dozen or more lozenges over a day, unknowingly accumulating a high dose of these polyols. This repeated, high-volume ingestion creates the physiological condition for digestive distress to occur. Even polyols like xylitol, which some people tolerate better than sorbitol, can cause watery stools at high doses.
Practical Steps for Prevention
The most effective way to avoid this side effect is to be mindful of the ingredients and the quantity consumed. Consumers should check the ingredient list for sugar alcohols like sorbitol, mannitol, or xylitol, especially in products labeled “sugar-free.” Limiting the total number of drops per day is the simplest mitigation strategy, as the effect is directly linked to the cumulative dose.
If frequent use is necessary, consider switching to cough drops that use regular sugar or honey as the sweetener, provided this aligns with dietary needs like managing blood sugar. Another option is seeking lozenges sweetened with erythritol, which is generally absorbed better by the small intestine and causes fewer gastrointestinal symptoms than sorbitol or mannitol.
For those who must use sugar-free drops, consuming them with food may help slow transit time and reduce the osmotic effect. Hydration is important to counteract fluid loss from diarrhea, and drinking water after dissolving a lozenge helps rinse the mouth. By managing the dose and selecting products carefully, the throat can be soothed without causing digestive upset.