To describe hospital presentations related to the use of naltrexone implants, an unlicensed product used in Australia for treating heroin dependence.

Retrospective case file audit.

Two Sydney teaching hospitals.

Identified through referrals to Drug and Alcohol Consultation–Liaison services over a 12-month period, August 2006 to July 2007.

Diagnosis, management and duration of admission.

Twelve cases were identified: eight were definitely or probably related to naltrexone implants or the implantation procedure (rapid detoxification). Of these, six patients had severe opiate withdrawal and dehydration, with an average hospital stay of 2.3 days. One patient had an infection at the implant site, and one an underlying anxiety disorder requiring psychiatric admission. Three patients had analgesia complications, and one had unrelated cardiac arrhythmia.

These severe adverse events challenge the notion that naltrexone implants are a safe procedure and suggest a need for careful case selection and clinical management, and for closer regulatory monitoring to protect this marginalised and vulnerable population.