You may have heard ketamine referred to as a ‘horse tranquiliser’ or ‘special k’, and while the former is true, it’s used widely in the veterinary field for a range of animals. It’s also used in low doses as a strong general anaesthetic for humans during surgeries and treatments.
Developed in the early 1960s, ketamine was soon used as a ‘battlefield anaesthetic’ because, unlike opioids, it provided pain relief and sedation without significantly suppressing the respiratory system. While the usage of ketamine to treat mental health issues like treatment-resistant depression has also been explored, it’s not a licensed treatment for depression in the UK.
Ketamine is a dissociative anaesthetic, which means it makes the user feel detached from their pain and environment. It can also cause hallucinations and this, along with its ability to make you feel relaxed, has contributed to continued recreational use. ONS figures for the year ending March 2025 estimated ketamine use at 0.8% of people aged 16 to 59 and 2.0% of people aged 16 to 24 in England and Wales. 
How Ketamine Affects the Human Body
Ketamine works by affecting the neurotransmitter glutamate. At high doses, it blocks NMDA receptors in the brain, producing its anaesthetic effects. At lower doses, this same NMDA receptor blockade enhances glutamate signalling, leading to hallucinations and altered perceptions.
Ketamine may also be responsible for rebuilding connections or synapses between neurons in the brain, which can sometimes be lost when a person suffers from depression. Some studies suggest that ketamine can have a short-term positive effect on individuals suffering with depression. And while there is established evidence of cognitive and psychological harm with chronic abuse, the long-term effects of ketamine use are still being studied.
‘Self-medicating’ with ketamine can be extremely dangerous and should never be attempted.
The physical effects of ketamine usually begin soon after taking the drug, and within a couple of minutes, users may experience an initial increase in heart rate and blood pressure. These effects generally decrease over the following 10-20 minutes, which is what can lead to some users taking more than they need, increasing the risk of overdose.
Other physical effects that occur due to ketamine usage include:
- Stiffened muscles
- Rapid eye movements
- Dilated pupils
- Excessive saliva production
- Tears running from the eyes
- Unresponsive to external stimuli due to the dissociative state
Ketamine users who are still wholly or partially aware of their surroundings may also experience confusion and clumsiness, slurred speech, blurred vision, anxiety and panic. Ketamine may cause some people to feel nauseous or sick, with the dissociative state sometimes referred to by recreational users as falling into a ‘k-hole’.
Does Ketamine Have Legitimate Medical Uses?
Ketamine is now primarily known for its recreational dangerous uses. But it does have medical applications in hospital settings as an anaesthetic and a pain medication, and, under careful monitoring, it is a highly effective and safe medicine. More recently, clinical research has also shown promising results so far with ketamine being used to treat mental health conditions (e.g. treatment-resistant depression) in certain circumstances, especially with those who haven’t responded to previous alternative treatments. Although ketamine has its place in medicine, it always involves controlled, measured doses which are administered by professionals, as well as ongoing medical supervision and monitoring. Self-medicating with ketamine outside of these settings carries the risks of serious harm.
Street Ketamine vs Medical Ketamine
Street ketamine is completely different to pharmaceutical grade ketamine, and it’s common for it to be contaminated. It’s also often less pure. It’s unregulated, there’s no quality control involved, and it can be diluted with other substances that look similar. This makes it very difficult to gauge safe dosing, and it makes taking ketamine very unpredictable, which is what increases the risk of overdose.
What’s the Legal Status of Ketamine?
Ketamine is a class B drug in the UK. So, this means that currently the possession without a prescription is illegal and can result in up to five years imprisonment and supplying or producing ketamine can lead to 14 years imprisonment and an unlimited fine. The government is considering moving it up to a Class A because of the increased number of people using it recreationally and the negative complications that have come from misuse.
What Are the Dangers of Ketamine Use?
Like most strong drugs, ketamine abuse has been linked to a long list of potential side effects. The NHS has reported that the following side-effects may be linked to ketamine infusion therapy, which is sometimes used as an alternate treatment to depression:
- Nausea / vomiting
- Anxiety
- Headaches
- Tinnitus (ringing in the ears)
- Increased blood pressure & heart rate
- Hallucinations and visions
- Mania
The research also notes that long-term ketamine use can cause liver damage and that illegal use of the drug outside of a clinical setting can lead to addiction. There is also the potential of a ketamine overdose occurring in individuals ‘self-medicating’, which in some cases, can lead to death.
A recent review of the limited scientific studies on the subject found that chronic ketamine abuse was linked with long-term cognitive impairment, certain mood disorders, and dissociative symptoms like psychosis. The authors also noted that “prolonged ketamine use may indeed negatively affect brain structure and functioning”.
Other long-term effects of ketamine use include:
- Flashbacks
- Liver and kidney problems
- Abdominal pain
- Ketamine Bladder Syndrome
Ketamine Bladder Syndrome is a painful condition that may require ongoing treatment, and can cause incontinence and lead to ulcers in the bladder.
Can Ketamine Kill You?
In short, ketamine overdoses are rare when the drug is taken alone, and deaths from ketamine alone are uncommon. And due to the minimal impact on airway reflexes and blood-circulation, the risk of death from using ketamine on its own is low compared to other drugs like opioids (which can restrict airways).
However, like all drugs, an overdose is possible and can be extremely dangerous, and ketamine can be particularly dangerous when taken with other substances. When used with stimulants like cocaine and ecstasy, the extra pressure can overload the heart. Taking ketamine with depressants, like alcohol or heroin, can quickly lead to unconsciousness, causing you to stop breathing or even suffocate on your own vomit. In some instances, though rare, people have been known to die of exposure outside or drown in the bath after taking ketamine.
Ketamine Misuse Harm Reduction Support
For those who use ketamine despite the risks, there are actions you can take to help you lower the risk of severe consequences. If you are misusing ketamine:
- Do not use it alone and always have at least one sober person with you.
- Avoid mixing it with other drugs.
- Stay hydrated but do not excessively drink water, as this can increase organ stress.
- Do not inject ketamine. Snorting carries a slightly lower overdose risk.
- If someone becomes unconcious put them on their side to prevent choking.
- Know how to contact emergency services (call 999 for emergency help).
- Use in safer environments. Do not use near large bodies of water, heights or in situations where being unconscious is dangerous.
Overdose Symptoms and Warning Signs
It’s important to know the difference between normal ketamine effects and signs of overdose. Look out for:
- Dissociation
- Visual or auditory changes
- Confusion or disorientation
- Elevated heart rate and blood pressure (mild)
- Muscle stiffness or tension
- Severe respiratory depression or shallow, slow breathing
- Loss of consciousness or inability to be roused
- Extreme muscle rigidity or seizure-like activity
- Dangerously elevated heart rate or severe chest pain
- Uncontrollable or violent movements
- Severe hypertension (very high blood pressure) that doesn’t normalise
- Aspiration risk, vomit or choking while unconscious
- Blue tinge lips or nails (indicating low oxygen)
- Coma or complete unresponsiveness
- Finding it hard to speak
Delayed overdose signs can also happen hours after using. This can look like:
- Worsening respiratory depression
- Hypothermia
- Acute kidney injury (in this case, it might look like not being able to urinate or very dark pee)
When someone is using opioids, Narcan can be given to them to avoid an overdose. This won’t work with ketamine, and there is no specific treatment that can reverse it, which is why it’s important to know the risks beforehand.
Getting Help for Ketamine Addiction
If you are struggling with ketamine addiction, drug addiction or substance abuse issues, there is always help available. Organisations like Narcotics Anonymous can offer support, and mental health charity Mind has a good list of contacts and resources available in person, online or over the telephone.
Residential ketamine rehab can also be a very effective way to treat ketamine addiction. If you need help, contact us today or phone us on 01908 489 421 for confidential advice on the next steps to take.
Dr. Olalekan Otulana (Advanced Practitioner) - Clinical Reviewer - Last Reviewed: 12/06/2026 3:00 pm
Dr. Otulana is a highly skilled General Practitioner and Addiction Specialist. He possesses extensive expertise in the field of Substance Misuse Management and boasts a diverse background in evaluating, overseeing (including detox procedures), and overseeing the residential recovery of individuals grappling with various drug and substance addiction issues. His primary goal is to conduct thorough assessments of patients dealing with addiction issues and determine their medical detoxification and psychological treatment requirements. Dr. Otulana is well-versed in caring for patients who need dual drug and alcohol detoxification therapies.
In addition to his medical qualifications, Dr. Otulana is a proficient healthcare professional who holds a Master of Business Administration (M.B.A.) degree from the prestigious Cambridge University Judge Business School.
