Some cough and cold medicines for children under 12 will be available only from pharmacies from next year.
The medicines safety authority, Medsafe, says it is reclassifying medicines which contain dextromethorphan and phenylephrine.
From May 2011, the cough medicines will be available only from pharmacies, in order that parents are able to get professional advice on how to use them for children.
Medsafe says products containing the ingredients will be available in supermarkets if they are re-labelled for adult use.