Cautions with codeine

Codeine is a weak opioid analgesic. It has to be converted to morphine, but there is significant inter-individual variation in its pharmacokinetics which results in variable effectiveness. Codeine's efficacy in clinical trials is generally modest and while its adverse events are generally mild, serious adverse events, including death, have occurred. Tolerance and drug dependence can occur. There is a risk of toxicity especially if combination products containing codeine and other drugs are misused. Treatment with simple analgesics, or other opioids if required, provides a more predictable response.