The manufacturers of the anti-depressant drug Seroxat have been asked for the second time in just over a month by the Irish Medicines Board to alter the patient information leaflet it supplies with the drug.
GlaxoSmithKline has now been asked to include a warning that the drug should not be given to under-18 year olds with major depressive disorder.
According to the IMB, the change follows recent clinical studies which showed "an increased rate of self-harm and potentially suicidal behaviour in children and adolescents treated" with the drug.
The studies, which were undertaken by GlaxoSmithKline, also found the drug was not effective in children and adolescents with major depressive disorder.
The company has been requested to ensure the new information is included in all product packaging within one month.
Last month it was ordered to withdraw a claim on its patient leaflet saying the drug was not addictive.
While Seroxat has not been licensed for use among under-18s in the Republic, the IMB estimated yesterday that up to 350 under-18s were taking the drug at present because doctors have the authority to prescribe any product for a patient under their care if they deem it appropriate in a particular case.
"The IMB wants to stress the importance for doctors, patients and parents to be aware of this new advice and for patients under 18 years who may be taking Seroxat to consult their doctor for advice," the IMB said in a statement yesterday.