Errors by hospital staff led to a 74-year-old man taking the first trial dose of a medication at home rather than in hospital and suffering a severe asthma attack as a result last year.
The Northland District Health Board has been asked to apologise.
Health and Disability Commissioner Anthony Hill says the man had a history of asthma and was seen in hospital by a consultant who prescribed the beta blocker Sotalol, with the first trial dose to be given in hospital where any side-effects could be managed.
He says that wasn't explained to the patient, who left the hospital that morning on the next available shuttle ride to his home some distance away.
When he had the first dose at home the next day, the reaction was so acute that he required local emergency treatment.
Mr Hill says poor communication led to the situation and a lack of clear clinical notes meant that no one was able to prevent it occurring.