Five teenagers at schools and colleges in Lancaster and Morecambe were taken to hospital after smoking vapes believed to contain dangerous drugs, said police.
Police believe the vapes could have contained "dangerous Class B drugs including amphetamine and THC".
They are urging parents to be vigilant after five pupils fell ill and required hospital treatment after smoking the vapes.
Supt Craig Kelshaw, of Lancashire Police, said: "The legal age to use and purchase vapes is 18, however, we know that they are being sold to young people via social media, and these are then being taken into schools and colleges.
“Not only is this a health issue, but those possessing and supplying illegal drugs could be committing criminal offences. We are working closely with local schools and partners to share information and intelligence.
“We would also urge parents, guardians and anyone with information they may have about those supplying these vapes to call Lancashire Police on 101.”
Cllr Michael Green, Lancashire County Council's cabinet member for Health and Wellbeing, added: "We are very concerned about the latest spate of young people becoming ill after using vapes believed to have contained illegal drugs across Lancashire.
“We know that our young people are obtaining these substances often via social media and using them in school settings.
"Vaping illegal and unknown substances carries significant health risks including becoming immediately unwell, loss of consciousness and even risk to life and we urge everyone to do their utmost to be vigilant and aware of the very significant dangers."
If you are concerned about a young person using drugs and vapes, please contact specialist support charity We Are With You via their website or on 0808 164 0074.
Anyone with information about the supply or use of these illegal vapes should contact Lancashire Police on 101 or Crimestoppers anonymously online here or by calling 0800 555 111.
Lancaster remains best university in North West England in Complete University Guide
'Music with the Mayor' initiative launched to support North Lancashire’s Citizens Advice
DIARY: Beyond Radio presenter fighting cancer continues his '60 Before 60' challenge
BIG FIGHT COUNTDOWN: Tyson Fury's father John headbutts Usyk supporter ahead of undisputed heavyweight title fight
Decision to refuse Galgate housing scheme planning permission upheld following public inquiry
INTERVIEWS and PHOTOS: The story of Highest Point festival 2024
INTERVIEW: Lancaster prison officer backed by Tyson Fury wins sport contest ahead of Miss England bid
VIDEO and INTERVIEW: Lancaster schoolboy, 10, makes drum 'n' bass DJ debut at Lancaster festival
Highest Point 'Lancaster Rocks' night cancelled due to thunderstorms warning
Quad bike rider dies after road crash in Morecambe
Morecambe guesthouse couple to star on reality TV show 'Four in a Bed'
PHOTOS: Northern Lights dazzle on Highest Point festival day one
Mother and son unveiled as new Lancaster mayoral team
New police and crime commissioner for Lancashire begins role
Morecambe homeless man jailed after admitting criminal damage
Firefighters tackle fire at flat in Morecambe
Lancaster youth charity awarded £221,400 towards vision for 'creative youth space' in city
Tennis club near Lancaster unveils new courts after £50,000 fundraising campaign
INTERVIEW: Highest Point chief 'proud' of lineup for 2024 festival
Highest Point festival stage times: all you need to know
