'If people feel unwell, they should seek medical help immediately, rather than waiting to see if the effects wear off after sleep and re-hydrating. '
Officers in Leicestershire have released advice as green pills, similar to those in the picture below, have been associated with a number of recent deaths and hospitalisations.
The warning is about counterfeit Oxycodone – Nitazene.
Leicestershire Police said: "We encourage people not to take these pills even in small amounts, and to consider the potential harm of taking any pills.
"If people feel unwell, they should seek medical help immediately, rather than waiting to see if the effects wear off after sleep and re-hydrating.
"At this time there have been no reports in Leicestershire but it is important that people attending events this weekend are aware of the risk."

Image released by Leicestershire Police
Deadline approaching for Leicestershire secondary school applications
Eleven arrested in Leicestershire vehicle crime crackdown
Leicestershire recycling centres launch ReHome Zones for unwanted household items
Hinckley Leisure Centre Car Park to be closed for one day
Police investigate seven courier fraud reports across Leicestershire
Four men bailed after Heather firearms incident
Police seek to identify three women after shop theft in Ibstock
Arrest in connection with Heather firearms incident