Doctors in the Wellington region are questioning the need for medicines combining anti-inflammatory drugs with codeine.
Doctors from Capital & Coast District Health Board have looked into the cases of seven patients admitted to Kenepuru Hospital's detoxification unit in the past two years.
They were addicted to codeine in products such as Nurofen Plus.
The physician in charge of the detoxification unit, Dr Geoffrey Robinson, who is also the DHB's chief medical officer, says those medicines contain more codeine than usual, and that may have triggered the addiction.
He says they also contain the anti-inflammatory ibuprofen, which was the likely cause of the patients' other ailments, such as peptic ulcers which bled and were resistant to treatment.
Dr Robinson says it is likely there are many more cases of undetected addiction to the codeine in over-the-counter medicines.