A dozen people have needed medical attention after taking what appears to be a tainted supply of the drug ketamine.

Public Health staff are urging users to avoid taking it.

If someone is experiencing any overdose symptoms, they should call an ambulance immediately by dialling 999.

The symptoms of a ketamine overdose are similar to what ketamine users experience as a high, but the side effects can be deadly – including dangerously slow breathing and unconsciousness.

Interim director of public health, Professor Hugo van Woerden, said: ‘We’re asking families, carers and others in contact with users to be vigilant for the signs of overdose which include: decreased levels of consciousness, shallow or irregular breathing – including periods where breathing may stop, slow heart rate which can cause cardiac arrest.’

Further advice and treatment is available from the Drug and Alcohol Team (DAT) on 617889. DAT is a confidential service for anyone who is concerned about their drug use.