What is Ketamine?

Green, K, Ket, Special K, Super K, Vitamin K, Donkey Dust

Ketamine is an anaesthetic with analgesic, stimulant and psychedelic properties. Chemically related to phencyclidine (PCP), it has been used extensively in human and veterinary medicine. Like PCP, it is a ‘dissociative’ anaesthetic which means that patients feel detached and remote from their immediate environment. Users say that under its influence they assume a different point of view, outside of body and self.


liquid pharmaceutical ketamine

The drug comes in a variety of forms. Pharmaceutical ketamine is usually a liquid. On the street it is more common to see tablets or a white crystalline powder.

Powdered ketamine is often snorted, though it may be swallowed.

If sniffed the effects of ketamine generally come on quickly and can last from about 20 minutes to a couple of hours.

The law

Ketamine is controlled as a Class B Drug under the Misuse of Drugs Act 1971. It was reclassified from Class C in June 2014. In November 2023 the government announced that three stimulants which create similar effects to ketamine – diphenidine, ephenidine and methoxyphenidine – will also be controlled as Class B drugs.

Penalties for possession are up to five years in prison and/or an unlimited fine. Supply holds penalties of up to 14 years in prison and/or an unlimited fine.

In practice, maximum sentences are rarely used. For more information please see the sentencing page on the Release website.


Ketamine is a dissociative anaesthetic, meaning users will feel detached from themselves and their immediate surroundings. The drug also has painkilling, stimulant and psychedelic effects. Effects are immediate if injected, though this practice is rarer, with most users sniffing the drug. If sniffed, the effects will take around 20 minutes to come on, and can last for one or two hours.

The amount of ketamine taken determines both the extent and type of effect the drug will have. At a relatively low dosage (around 100mg), users will commonly experience mild dissociative effects, hallucinations, and distortions of time and space.

Larger doses (anything above 200mg) may induce a so-called ‘K-hole’, where a user can experience considerable and lengthy detachment from reality. The user may experience hallucinations, similar to those while using LSD followed by numbness, often in the limbs, and strange muscle movements. Users may also feel sick or throw up. 


Concerns over the risks of using the drug have been growing in recent years. Repeated or heavy use of ketamine appears to be particularly harmful to the urinary tract and can cause ulcerative cystitis, where the bladder wall thickens. In some cases, individuals have had to have their bladders surgically removed. Frequent use can also cause kidney dysfunction and abdominal pains known as ‘K-cramps’.

The risk of death from accidents is also elevated while under the influence of ketamine. As a powerful analgesic, its use can make users more vulnerable to physical injury as the seriousness of an incident may not be immediately apparent. Its dissociative effects may also make users unaware of potentially risky behaviour. One study found that as many as 83% of 90 ketamine users knew of someone who had an accident while taking ketamine (Ketamine: a review of use and harm). Users can throw up and this can be very dangerous at high doses if the user is unconscious or disorientated as they may choke on their vomit.

Frequent use of ketamine may also lead to depression.

There is considerable evidence from ketamine users that heavy use of the drug can lead to dependence. Studies on animals, as well as reports from regular users, suggest that tolerance can develop, meaning that users need to take higher and higher doses to achieve the same effects.

Ketamine can be particularly dangerous if used at the same time as depressant drugs such as alcohol, heroin or tranquillisers. The combined effects of these drugs can cause the body to shut down to such an extent that the lungs or heart may stop functioning.

The first death in which ketamine was implicated was in 1997. From then until 2005 there were fewer than five deaths per year where ketamine was either found in post-mortem toxicology samples and/or implicated in death. The number of these cases increased until 2009, peaking at 26 and 21 respectively, since then the number of deaths has fallen. (Ketamine: a review of use and harm, Advisory Council on the Misuse of Drugs, 2013). According to the ONS’s response to a FOI request, Ketamine was referenced on 12 death certificates in 2015.


Ketamine first found its way onto the club and rave scene in the UK in 1992 when people took it thinking they were buying ecstasy.

The Home Office statistics published in 2020, report that while in recent years the use of ketamine in the last year has fluctuated, use has increased compared with a decade ago. For adults aged 16 to 59 years, prevalence increased from 0.5% in the year ending March 2010 to 0.8% for the year ending March 2020. Use among adults aged 16 to 24 years has also increased over the same period from 1.7% to 3.2%.

In the financial year ending 2022, the quantity of ketamine seized by police forces and Border Force increased by 884% to 1,837kg (from 187kg in the previous year). This was driven by an increase in the number of seizures over 10kg by Border Force (Seizures of drugs in England and Wales, financial year ending 2022).

Updated December 2023


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