In 2010, Ireland found itself at the eye of an international storm as a network of head shops emerged selling new psychoactive substances (NPS) and Irish youth rapidly became the heaviest users of NPS in Europe. Within months, the Irish government enacted novel legislation, which has since been copied by other countries, which effectively stopped the head shops selling NPS. Critics of this policy argued that it could cause harms to escalate. A number of separate studies indicate that a range of drug-related harms increased amongst Irish youth during the period of head shop expansion. Within months of their closure, health harms began to decline. NPS-related addiction treatment episodes reduced and admissions to both psychiatric and general hospitals related to any drug problem began to fall. Population use underwent sustained decline. Consequently, the closure of head shops can be viewed as a success in terms of public health.