Five students from Lancaster University have been hospitalised after taking the controversial legal high "Spice", the university has said.
Two of the five students are said to be critically ill, a university spokesperson also said.
"Spice" is a synthetic compound with similar effects to cannabis that has been widely condemned by health professionals.
A national campaign to raise awareness of the dangers of new psychoactive substances (NPS) - so-called 'legal' highs - among teenagers and young adults has been launched by the Home Office.
The radio, digital and mobile phone adverts are aimed at people aged 15 to 21 and warn them about the risks of taking the drugs.
The campaign focuses on the risks and harms associated with a range of legal highs including nitrous oxide, which is commonly known as "laughing gas".
Government scientists are being sent to the V Festival to analyse samples of so-called legal highs amid renewed warnings against taking the party drugs.
The Home Office is launching a national campaign highlighting the risks of legal highs including laughing gas, which was more widely used than powdered cocaine and ecstasy last year.
They are aiming to gather information about which new substances are available in the UK, and the latest Home Office annual report on the trends is due to be published today.
Legal highs are so popular the only option is to "educate people who are using them" about how they can make safer choices about the drugs they take, an addiction specialist told Good Morning Britain.
Associate medical director of the CRI, David Bremner, said: "In a matter of days a new drug will be released that will have one molecule changed that then beats the law so that it is no longer illegal...all we can do is educate people who are using them on how to make safer choices."
Professor Fabrizio Schifano, CRI's Consultant Psychiatrist, has been at the forefront of collating evidence around the UK's legal high situation.
Speaking about the Strange Molecules campaign, he said:
One of the UK's biggest drug and alcohol charities, CRI, has warned that the UK is "only scratching the surface" posed by Novel Psychoactive Substance (NPS) or 'legal high' misuse.
As part of its new campaign, CRI has launched strangemolecules.org.uk to keep young people informed of the facts as new drugs are discovered every week.
David Biddle, Chief Executive of CRI, says the charity is committed to informing the debate, he said:
"Some of these substances are highly potent and can be very risky, possibly up to 10,000 times stronger than the street drugs they emulate, with tiny amounts able to trigger extreme psychoactive responses."
Some of the UK's leading music festivals have joined a ban on "legal highs" being sold at their events and will take part in a "digital blackout" to highlight the danger of the controversial stimulants.
The social media accounts of 24 festivals, including T in the Park, Bestival and Lovebox, will go dark for a day from 9am on Monday, while their websites will show only a grey light bulb on a black window with the message: "Don't be in the Dark about Legal Highs."
The number of deaths associated with the novel psychoactive substances - better known as legal highs - rose from 10 in 2009 to 68 in 2012, a recent substance abuse report found.
Home Office minister Norman Baker has warned that authorities are in a "race with chemists" in India and China who generate new legal highs on a weekly basis.
"More people are dying" from taking legal highs and other "designer drugs", anti-substance abuse campaigners have warned.
An spokesman for the National Programme on Substance Abuse Deaths (NPSAD) dismissed claims the number of deaths caused by legal highs were over reported: