Medsafe (Medicines and Medical Devices Safety Authority) supervises the ADR (Adverse Drug Reaction) reporting for medicines and medical devices. Medsafe operates under the Medicines Act 1981 which mandates sponsors to report substantial untoward effects of their medicines. Anyone including the public, health professionals, and the therapeutic goods industry, can report ADRs to the Centre for Adverse Reactions Monitoring (CARM) online or by phone, post, fax, and email. Medsafe assesses the causality of suspected ADRs, whether confirmed or not. Reporting is voluntary for clinicians and the public but mandatory for sponsors of both registered and listed drugs.

Medsafe focuses on adverse events related to new drugs, drug or vaccine interactions, unlisted suspected adverse events, and serious events such as death, hospitalization, or congenital defects. The CARM database maintains information on adverse events in New Zealand. Challenges for Medsafe include underreporting of side effects and lack of comorbidity data, which can hinder identifying factors contributing to adverse events.