Lactulose is a synthetic sugar used as a laxative and prebiotic. However, it may contain impurities that can affect its safety and efficacy. These impurities can originate from the manufacturing process or from degradation of the active ingredient over time. Common impurities include epilactose, lactose, galactose, and fructose, which can cause gastrointestinal side effects and decrease the potency of lactulose. Therefore, it is important to monitor and control lactulose impurities to ensure its quality and purity.