The new drug, known on the street as Spice or Fake Weed, can cause severe psychotic episodes, violent hallucinations, nausea and seizures.
According to figures compiled by Westminster Council, a fifth of the 430 rough sleepers who stayed in hostels in central London were on the drug between January and April of this year, compared with zero number of drug abusers in 2014.
"Evidence from drug service providers suggests that [spice] is a rapidly growing problem among marginalized and vulnerable communities, including the homeless," Steve Rolles, senior policy analyst at drugs charity Transform, told Sputnik.
Rolles does however blame current legislation prohibiting the consumption of cannabis in the UK for fueling the illegal market for dangerous and cheaper alternatives.
"Where cannabis is legally available, as in the Netherlands, for example, there is no market for these products as people can just use cannabis, which is safer and generally preferred. So, it is very clear that it is cannabis prohibition that has created this problem and only a legally regulated market for cannabis will reverse this." Mr. Rolles said.
Homeless charity outreach workers have described users suffering uncontrollable fits, followed by crashes when they become unresponsive.
Ewa Kapica, an outreach worker at Westminster-based homelessness charity The Connection at St Martins-in-the-Fields, said: "I've witnessed people trashing around on the floor, experiencing vivid hallucinations, screaming they want to 'end it all.' These fits are followed by crashes; the person becomes unresponsive and the emergency services step in. It's terrifying," Ms. Kapica said.
Councillor Nickie Aiken, cabinet member for public protection and Westminster City Council said: "Spice is cheap, readily available and highly addictive, so it's little wonder our support services are seeing an increase in the number of users.
"In just two years a new drug epidemic has taken over the streets of London."
Nickie Aiken: Spice – the new drug epidemic sweeping the streets of London | Conservative Home https://t.co/vnzOiIXlkY— James Cockram (@fuimus) October 4, 2016
Synthetic cannabinoids are generally "more potent and toxic" and for drug users, have an advantage over heroin and crack because, "they offer a relatively cheap way to get very intoxicated" and that possession of synthetic cannabinoids, such as spice, "is not a crime under the new NPS Bill [psychoactive substances act]."
"So from a user's perspective, they have an additional advantage over drugs like heroin or crack," Mr. Rolles told Sputnik.
But it's not just the streets of London where Spice has become a problem, according to Mr. Rolles, it is fast becoming a problem in prisons as well.
"Partly because it is not usually detected by current testing regimes so it is easy to smuggle and clandestinely consume," Mr. Rolles told Sputnik.