A "bad batch" of recreational drugs that has seen more than a dozen people admitted to Christchurch Hospital is three times the strength of MDMA or ecstasy, officials warn.
A 15-year-old is among those who received hospital care after taking the drug.
Nine people were admitted over one weekend in late February suffering from side effects from the drugs and another four people presented to the hospital's emergency department the following Monday.
Canterbury District Health Board's Emergency Medicine Specialist Paul Gee said duty doctors at the ED were astute in realising the patients' behaviour was different from the usual MDMA or ecstasy side effects.
Further medical analysis identified the substance taken by the patients was in fact N-Ethylpentylone, rather than MDMA or ecstasy.