What is it?
Ketamine is a powerful general anaesthetic that's used for operations on humans and animals.
It is also known as Ket, Horsey, K, Special K, Vitamin K
It is categorised as an hallucinogen.
What it looks like
When used as a medical anaesthetic, ketamine is a liquid, because this makes it easy to inject. 'Street' ketamine is normally a grainy, white powder - although sometimes it can come as tablets.
How it's taken
Ketamine can be swallowed, inhaled or injected.
The effects don't last long, but until it wears off, ketamine can cause a loss of feelings in the body and paralysis of the muscles. It can also lead to users experience 'out of body' experiences, numbness and hallucinations.
Ketamine is risky in a number of ways:
Ketamine is a Class C drug. This means that it's illegal to possess it, give it away or supply it. Possession can get you up to two years in prison and/or an unlimited fine. Supplying someone else, even your friends, can get you 14 years in jail and/or an unlimited fine.
The President of Colombia, Juan Manuel Santos, has used his Nobel Peace Prize acceptance speech to call for the world to "rethink" the war on drugs.
He said the zero-tolerance policy might be "even more harmful" than all the other wars being fought worldwide.Drugs workers fear a "bad batch of heroin" could have led to the deaths of at least seven drug users in recent weeks in the Gwent Police force area.
Drugs workers fear a "bad batch of heroin" could have led to the deaths of at least seven drug users in recent weeks in the Gwent Police force area.
According to NHS figures, 1,087 babies in England were affected by maternal use of drugs in 2014-15, while in Scotland 987 babies were affected.
The Metropolitan Police has said it will examine 58 GHB-related deaths, following the conviction of serial killer Stephen Port.
A leading police chief says recreational drug testing "may be very useful". Commander Bray is in discussion with the government about it.
Britain should follow America's lead and legalise cannabis, and rake in £1 billion a year in tax revenues
Marijuana legalization will unleash misery on Arizona, according to a wave of television ads that started rolling out across the state last month.
Police in Denmark have arrested a man and woman on suspicion of providing cannabis to cancer patients and people with other serious illnesses.
The National Drugs Helpline is a 24-hour, 7-days a week, free and confidential telephone service that offers advice and information for anyone.
It is run by the government agency, known as FRANK, created to provide drug support and advice for the public.
If you need emergency help, are worried about a friend or relative's drug use or want support coping with your own, contact FRANK on-line contact or by phone.
Doctors trialling the use of ketamine to treat depression are calling for the treatment to be rolled out.
Ketamine is licensed as an anaesthetic but has a reputation as a party drug.
Writing in The Lancet Psychiatry, Dr Rupert McShane, who has led a trial in Oxford, since 2011 says ketamine can work on patients with depression "where nothing has helped before".
Antidepressants are among the most commonly prescribed drugs throughout the western world. In fact, they are prescribed more than any other drug for Americans aged 18 to 44, and they are now taken four to five times more frequently than in the early 90s. In the UK, antidepressant use has doubled over the past decade. Either more people are depressed, more people are talking about their depression, or doctors now think they have got a pill that will help.
Scientists believe that a radical treatment involving the tranquilliser ketamine could help overcome alcohol addiction by "erasing" drink-related memories.
Psychologists based at University College London are testing whether a one-off dose of the drug could help hazardous drinkers who are trying to reduce their alcohol intake. Alcohol addiction is notoriously difficult to treat, and there are few effective therapies available.
Ketamine hydrochloride is a synthetic dissociative anaesthetic, synthesized in the 1960s for medical use, and used medicinally during the Vietnam war. It is usually consumed by snorting a white crystalline powder, at lower doses than when used as an anaesthetic. However it can also be injected, or smoked.
When ketamine is snorted, it gets into the blood stream quickly, and intoxication effects occur soon after it's taken. At low doses it raises heart rate.
A new study claims that the antidepressant effect of ketamine is caused by the metabolic breakdown of the drug, not the drug itself.
The study found that a compound called hydroxynorketamine was responsible for a lift in mood in mice given ketamine. The metabolite is a product of the molecular breakdown of ketamine and when given this metabolite, mice did not experience any of the side effects associated with ketamine.
A substance produced after taking the drug ketamine could be used to create a fast-acting anti-depressant without its harmful side-effects, say scientists.
Ketamine, banned in the UK in 2006, initially used as a horse tranquiliser, is now better known for clubbing and date-rape. Clinical trials have shown it can relieve depression faster than commonly prescribed drugs, but it also created the dissociative, euphoric and addictive properties that made it an illegal drug.
My supply of ketamine is under threat and you should be worried. I'm not a drug addict. I'm an anaesthetist, and to me ketamine is medicine.
In rural hospitals in Nigeria, injecting the drug is essential for safe ceasareans, and to insert IVs for fluids and attach monitors to children without a struggle. It can be used for preventing pain. Some colleagues even advocate the use of oral ketamine for procedures in the accident and emergency department.
This week, a survey of over 10,000 college students has confirmed what reports around the UK have hinted at: Ketamine is again in plentiful supply.
Student website the Tab's annual university drug survey found a significant rise in the number of students in the UK using ketamine in 2016 compared to 2015. The survey also found that students are now paying less per gram than the inflated prices dealers were charging during the drought of 2014 and 2015.
Police in China are battling to contain the illegal recreational use of ketamine, which is soaring among the country's young people, eclipsing heroin.
In the village of Boshe, underground laboratories are producing ketamine cheaply in large amounts.
The BBC's Celia Hatton reports from Boshe, where the trade in producing the drug lives on, despite repeated police raids.
One of the biggest drug raids in China's history took six years to plan and 14 hours to execute.
The target? The village of Boshe, a drug haven known by local people as "The Fortress".
Before the raid, they thought Boshe was impenetrable.
China is proposing there should be a worldwide ban on ketamine but ketamine is used as an anaesthetic drug in much of Africa, and there are fears further international controls could affect medical usage too.
In Lusaka's main hospital Dr Jane Kabwe examines a young woman who has just given birth "I had a heavy bleeding so I was transferred here - I feel dizzy and not well enough to stand up."
A proposal that is about to come before the UN to restrict global access to ketamine, a drug abused in rich countries, would deprive millions of women of lifesaving surgery in poor countries, according to medicines campaigners.
Ketamine, known a variety of names including ket and Special K, is one of the most commonly used anaesthetics in the developing world. As it is injectable, it can be used in rural areas where anaesthetic gases are unavailable.
Ketamine, a psychoactive 'party drug' better known as Special K, has pharmaceutical companies riding high. It has proved an extremely effective treatment for depression, bipolar disorder and suicidal behaviour.
Unlike conventional antidepressants, ketamine lifts depression in as little as two hours. "It blew the doors off what we thought about depression treatment," says psychiatrist James Murrough at Mount Sinai Hospital in New York City.
The illegal party drug ketamine is an "exciting" and "dramatic" new treatment for depression, say doctors who have conducted the first trial in the UK.
Some patients who have faced incurable depression for decades have had symptoms disappear within hours of taking low doses of the drug. The small trial on 28 people, reported in the Journal of Psychopharmacology, shows the benefits can last months.
The father of an 18-year-old woman who died after taking the drug ketamine has described how "one act of stupidity has destroyed our family".
Bradley Rowe made the comment as it was announced the drug is to be upgraded to a Class B banned substance. Ellie Rowe, from Glastonbury, Somerset, took the Class C drug while at the Boomtown Fair festival in Winchester.
New types of drugs for schizophrenia, depression and other psychiatric disorders are few and far between - and a number of companies have scaled back or dropped development of this class of pharmaceuticals. One exception stands out. Ketamine, the anesthetic and illegal club drug, is now being repurposed as the first rapid-acting antidepressant drug and has been lauded as possibly the biggest advance in the treatment of depression in 50 years.
When it first took hold in Britain, it was closely associated with dance music, but it has spread to the mainstream, taken at parties and in homes in cities, towns and villages across the country.
Ketamine is an anaesthetic with hallucinatory properties. Users feel detached from their body and surroundings. Surgeons in Leeds, London and Bristol say there are a growing number of people struggling with severe side effects.
When Vicky and Ross woke on Wednesday 2 March, they had no reason to think the day would not be like any other. They were at their flat in Geneva and their first thought was for their children in London, Tommy, 23, and Louise, 21.
Ross set off for work, and Vicky prepared for her daily routine. Everything seemed normal. Then, just before his 8.30am meeting, Ross's phone rang with the news that Louise was dead after taking ketamine.
Ketamine is increasingly replacing cocaine as the substance of choice among Britain's recreational drug users, according to charities and experts.
Use of the drug, known as "Special K" or "Raver's Smack", was found to be on the rise in nine out of 20 areas surveyed by the charity DrugScope. The British Crime Survey shows that use of the drug last year increased nationally by 10 per cent on 2006-07.