A senior paramedic has warned that so-called legal highs are leaving ambulance services baffled when it comes to treating casualties.
Sarah Harrison said the complex make-up of the substances is leaving staff playing “catch-up” in the battle to develop effective treatments.
A BBC investigation has discovered some products did not contain the precise ingredients listed on their packaging.
Police incidents involving legal highs have more than doubled in two years.
Officers from 32 forces in England attended 3,807 incidents in 2014 – up from 1,431 the previous year, according to data compiled by the think tank the Centre for Social Justice.