Detectives have launched an investigation into whether a man died after taking the legal high known as Spice, Avon and Somerset Police have said.
A 30-year-old man was found unresponsive and subsequently died.
Six other people exhibited symptoms but did not attend hospital.
The seven people affected were all known to each other and were at the same address in Wheatley Crescent in Taunton when police were called by the ambulance service on Wednesday.
Police are now investigating the supply of the legal highs – an offence under the Psychoactive Substances Act 2016.
Avon and Somerset Police are investigating whether there is an evidential link between the incidents.
There is information to suggest that some of those affected may have taken the Psychoactive Substance (PS) commonly referred to as Spice.
DCI Liz Hughes said: “These are clearly serious incidents and we are warning people not to take these so-called legal highs.
“If you take an PS you are playing roulette with your health.
“Many of these types of products have not been tested on humans and can contain chemicals which, if consumed, can leave you at a grave risk of suffering serious ill health and can even prove fatal.”
The substances are often sold as plant food, incense or research chemicals, with some labelled “not fit for human consumption”.
They often have product names similar to the street drugs they mimic.