Parents are being warned to stop giving a popular medicine to young children due to risky side effects.
It comes after mood and behavioural changes were detected in young children taking the oral antihistamine promethazine.
The medicine, sold under the brand names Phenergan, AllerSoothe and AdiraMedica-Promethazine, should not be used for children under six years of age, Medsafe warned.
"Do not give any child under six years of age promethazine tablets or promethazine elixir," Medsafe said in a statement on Tuesday.
Being an antihistamine, antipsychotic, sedative, and antiemetic, the medicine is often used to treat allergies, insomnia and nausea.
"A safety review by Sanofi, the company which makes Phenergan Tablets and Elixir, found a link between promethazine and mood and behaviour-related side effects in children under the age of six.
"Due to these risks, oral medicines containing promethazine are now restricted to use in adults and children aged over six years only."
Medsafe warns those who have children using promethazine to speak with their pharmacist or doctor about alternative options.
"There will be a time lag before promethazine products with updated package labelling for use in children aged over six years only will be available in pharmacies. Always check with your pharmacist or doctor if a medicine is suitable for your child."
Anyone with side effects is urged to report it to the Centre for Adverse Reaction Monitoring (CARM).
