Parents in a Berkshire borough are being warned that their youngsters could get hold of a dangerous drug, sold as a plant fertiliser.
The Royal Borough of Windsor and Maidenhead Council's drugs and alcohol team said Mephedrone, known as "Bubble" or "Michael", is easily available.
It added that some young people who have used Mephedrone had already contacted their treatment service.
Side effects from taking the drug can include paranoia and depression.
Councillor Simon Dudley, the council's lead member for adult and community services, said: "As with any drug, the effects can vary when taken by different people, under different circumstances.
"I would urge parents to be on their guard particularly at this time of year, during the Christmas festivities."