Mexxy, or methoxetamine, is the first-so called legal high to be banned temporarily under Home Office powers which can restrict a substance for up to 12 months while it is decided whether it should be made completely illegal.
The drug is new on the UK market with many unsure of what exactly it is.
Used as a supposedly-safe alternative to Class C drug Ketamine, it is a dissociative anesthetic which has been blamed for the death of a 17-year-old boy.
Drugscope's director of communications Harry Shapiro told The Huffington Post UK: "There are plenty of reports out there about this drug being not much different in its effect from ketamine.
"Ketamine is a dissociative anaesthetic which causes some 'weird effects' including out of body experience.
"It creates a sense of escapism and alienation which means people can fall over and hurt themselves and can lead to severe damage to the bladder. The thing about Mexxy is there's no indication that it is safe and does not harm your bladder."
Elliot Elam of Addaction said: "Two people were found dead in Leicestershire last month (in two separate cases), and it was suggested that Methoxetamine was the cause of their deaths, but we have seen no evidence as yet to confirm this as yet.
"We also haven't seen it, as yet in our services, but we have heard anecdotal reports of its use. And as you might expect, we strongly advise that people don't take it. 'Legal' doesn't necessarily mean 'safe' and you can't be sure that the drug you've bought - even if you've tried it before - won't cause you major problems, especially if you mix it with other drugs, or with alcohol. Using ketamine and alcohol can be very dangerous, for example, causing vomiting, blackouts and worse. As 'Mexxy' is similar in chemical structure, the risks could be similar, also."
Professor Les Iversen, chairman of the Advisory Council on the Misuse of Drugs, said as a drug which was similar to ketamine, users could experience the same "serious effects" of ketamine as well as "agitation, cardiovascular conditions and hypertension."
Some on Twitter remain sceptical about the ban, congratulating the government for giving the little-known drug some publicity. See below for a slideshow of the best tweets.