Toxicology is the field of science that examines the effects of chemicals, substances, or situations on people, animals, and the environment. A mass gathering is the congregation of a large group of people, usually involving more than 1000 individuals. Mass gatherings can be for any purpose, but are often related to religious, political, and sporting events. Toxicological concerns in mass gatherings include exposures such as toxic gases, contaminated food and beverage supplies, ethanol use, or recreational drug use. The most common concerns are related to ethanol and cannabis use. Providers at mass gatherings should be prepared for a wide range of toxicological challenges. A general understanding of basic toxidromes can further aid in management. Toxidromes can be considered broadly as stimulants/hallucinogens or central nervous system depressants. Management of the undifferentiated intoxicated patient should primarily emphasize support of airway, breathing, and circulation. Providers must also be aware that polysubstance use is common and individuals may present with effects and unpredictable clinical courses. Awareness of toxicological concerns that will present at a specific mass gathering can mitigate risk. Providers should be ready and to adapt to changes and unexpected outcomes.