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."
More top news
A man and woman have been arrested on suspicion of murder after a badly burned body was found in a garden in Southfields, south-west London.
Kim Jong-un has called Donald Trump "deranged" and says he will "pay dearly" for his threats, according to North Korea's state news agency.
Theresa May will tell European counterparts their shared political legacies depend on agreeing a good Brexit deal.