An 18-year-old man has been arrested in connection with the supply of a dangerous drug known as "Rockstar".
Seven people were treated in hospital over the weekend after apparently taking one of the tablets circulating in the Lanarkshire area.
The red or yellow-coloured pills were allegedly being sold as ecstasy.
A Strathclyde Police spokeswoman said: "An 18-year-old man has been arrested and is presently detained in police custody in connection with alleged drug offences.
The teenager is expected to appear before Airdrie Sheriff Court on Tuesday.