BACKGROUND: New psychoactive substance (NPS) use can negatively impact health and may result in drug-related hospital admissions (DRHAs). Irish youth reported very high rates of NPS use by international standards, the most common being synthetic cannabinoids and cathinones. There was a rapid expansion in specialist shops, called head shops, selling NPS in 2010. Government responded to public protests about head shops by enacting legislation in May and August 2010 to end this trade. Many academics argued that such actions would prove futile. We sought to determine if changes in head shop activity coincided with changes in DRHA.

METHODS: The national database on admissions to general hospitals hospital in-patient enquiry was examined focusing on young adults admitted from 2008 to 2012, and all emergency admissions with an International Classification of Diseases-10 diagnosis of mental disorder related to any drug (F11-F19) were identified. Joinpoint regression analysis was utilized to explore for the presence of trend changes in DRHA.

RESULTS: Joinpoint regression analysis identified a significant downward trend change which occurred in June 2010 (95% CI February 2010 to January 2011). DRHA increased by 0.5% (95% CI 0.1-0.9) per month prior to this and then fell by 2.6% (95% CI -1.4 to -3.8) per month over the next 16 months.

CONCLUSIONS: Cessation of NPS sale by head shops coincided with a reversal in the upward trend of emergency hospital admissions related to drugs. Although correlation does not confirm causation, legislation which successfully curtails the commercial sale of NPS may result in reduced hospitalizations.