A campaign highlighting the potentially lethal results of mixing drugs and alcohol is being run by the Oxfordshire Drug and Alcohol Action Team.
Support officer Pasquale Brammer said taking cocaine and alcohol creates a toxic substance in the body called cocaethylene, which can be fatal.
"What we don't know is the toxic chemicals produced when mixing newer drugs," he added.
They hope to raise awareness among people celebrating this Christmas.
The latest figures for October show there were more than 370 people admitted to an emergency department in Oxfordshire because of alcohol and more than 70 because of drugs.
As well as beer mats and posters they have also produced short animations about the dangers of mixing drugs and alcohol on YouTube.