A young person is in a "critical condition" as super-potent pills circulate in Bristol and North Somerset, a school has warned.
Cotham School says it had been advised by Avon and Somerset Constabulary of a substance similar to the anxiety drug Xanax - but this batch is thought to be eight times the normal strength.
Xanax is the brand name for a medicine called alprazolam, and there have been rising concerns in recent years about the counterfeit market.
A school newsletter sent to parents last week said: "Avon and Somerset Police have been made aware that the prescription drug Zannex [sic] is currently circulating.
"This has been noted as 8 x stronger than it would normally be.
"We believe this to be found mainly within North Somerset, however was recently taken in Bristol.
"We were made aware the young person concerned is sadly currently in intensive care and in a critical condition."
There is no suggestion the person is a pupil at the school, and no further information was given about the person's age.
Bristol Live has contacted the police force, school and Bristol and North Somerset councils for further information.
The problem of counterfeit Xanax and particularly its use among young people has been widely-reported in recent years.
Last year the coroner for Northern Ireland called the issue an "escalating crisis," following a number of deaths linked to fake versions of the drug.
The number of young people in Bristol, who have been admitted to hospital due to substance misuse, has risen dramatically over the last decade.
What is Xanax?
Xanax is a brand name for a medicine called alprazolam, which is in the benzodiazepine family of drugs.
Benzodiazepines are usually prescribed to treat anxiety and insomnia, and to control epilepsy seizures.
A student at the University of the West of England took her life in 2017, after struggling with withdrawal symptoms from Xanax.
- Samaritans is available to call day or night on 116 123, for anyone who needs mental health support
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Public Health England advises: "Alprazolam can cause problems when taken without medical supervision. In the short term, its misuse can cause over-sedation, collapsing and overdose.
"Longer-term use can lead to physical dependence and severe withdrawal upon reducing or stopping use."
Prescription alprazolam is only available in the private sector, not through the NHS.
