Nonnutritive sweeteners (NNSs) and low-calorie sweeteners (LCSs) are commonly used as sugar substitutes. Many popular media Web sites caution against the use of these sweeteners because of their potential adverse effects such as inflammation; however, there are limited supporting data. A Medline search of articles published between 2010 and 2020 was conducted, resulting in 833 articles, of which 12 relevant studies were included in this review. Acute adverse effects associated with the consumption of NNSs and LCSs are rare. A few studies cite reports of acute adverse effects, including mild gastrointestinal disturbance, headaches, lightheadedness, hypersensitivity reactions, impaired spatial orientation, depression, and pain. Little scientific evidence has been reported in the literature since 2010 to support these warning statements to consumers about acute adverse effects to NNSs and LCSs.