Novel psychoactive substances or 'legal highs' can be defined as psychoactive substances that have been developed to avoid existing drug control measures. Consistency of name, but with change in the content of the product, may cause harm. This could result in clusters of users being poisoned and developing unexpected physical and psychiatric symptoms. We describe such an event and the clinical phenotypes of a cluster of patients poisoned with a novel psychoactive substance in 'ivory wave' and analyze data from the National Poisons Information Service (NPIS) to estimate use across the United Kingdom. In addition, the likely active ingredient in this cluster of 'ivory wave' poisonings was identified.