All drug use has risks. This page is for information only and does not constitute or replace medical advice. If you have medical concerns about your drug use, please speak to a medical professional.
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Ketamine is used as an anaesthetic in human and veterinary medicine. It is also used on the recreational drug scene and can produce feelings of relaxation, detachment and euphoria. People may also have psychedelic experiences.

Other names

ket, K, special K, keta


Off-white or brown crystalline powder/shards or clear, odourless liquid

Drugs Wheel Category



Misuse of Drugs Act (1971) – Class B.

If prepared for injection ketamine becomes a class A drug.

Penalties for possession are up to five years in prison and/or an unlimited fine. Penalties for supply are up to 14 years in prison and/or an unlimited fine.

How it’s taken

Ketamine is most commonly snorted, but it can also be swallowed mixed into a drink or wrapped in a cigarette paper (bombed) or put into a gel capsule. It can be injected into a muscle, but this is strongly discouraged. Injecting ketamine does not reduce the risk to the bladder and increases the risk of blood-borne virus transmission, infection and overdose.


The following information on dosage was taken from PsychonautWiki, but this should not be taken as a recommendation: duration and effects of any drug will depend on purity, regularity of use, other medications or drugs you have taken, your body and how it is taken (route of administration).   Swallow: 

  • Light: 50100 milligrams (mg) – this would give 10 to 20 bombs from a gram  

Insufflate (snort):  

  • Light: 10-30 milligrams (mg) – this would give 33 to 100 lines from a gram  
  • Common: 30–75 milligrams (mg) – this would give 13 to 33 lines from a gram  

Accessed May 2020     These are average doses, for an average person of average build. If injecting these amounts would be less.  The effects of ketamine are dose dependent — the higher the dose the more “dissociative” the effects and the stronger the effects on balance and coordination are  Keeping doses low will avoid tolerance to ketamine which can build up quickly. Tolerance means you need to take increasing amounts to get the desired effect.  It is essential to use accurate scales – ones that are capable of measuring to 10 milligrams (0.01 of a gram). Knowledge of how to use them and how to ensure they are measuring accurately is important.    A slight difference in dose can create a different experience or effect. Find out more about reducing the risk from dosing including volumetric dosing.   General information on dosing. 

General information on dosing.


The onset of effects of ketamine, when snorted, will be felt within 5 minutes and the effects can last for 1–2 hours.  If swallowed the effects can be felt within 30 minutes and may last for up to 3 hours. After effects may be felt for several hours.  Ketamine can slow down messages from your body to your brain, make you feel detached from your surroundings and change your perception of time.  

  • Low doses taken in a club can be stimulating with increased energy and a pleasant high whereas taking it in a quiet, relaxed place with friends can be spiritual and calming.  
  • Higher doses tend to be trippy with people describing an out of body experience called a ‘k hole’. A ‘k hole’ is the complete detachment or dissociation from your surroundings. There is not set dose for a ‘k hole’ and it will vary between people depending on tolerance, body size, metabolism etc. People k-holing may be unresponsive, tripping in their heads and unable to move. 

Other effects may include feeling floaty, numb and pain-free. Ketamine can affect your balance and coordination and make it more difficult to move about safely.   Frequent (weekly) and/or long-term ketamine use can permanently damage the bladder. 

Harm reduction

If you choose to take ketamine then the following steps can help to reduce harm.


  • Spend at least two hours researching the drug you are planning to take.  
  • Eat two hours before taking to reduce the chance of being sick. 
  • Test the drug. If you don’t have access to a drug testing service, reagent testing kits are available online and can give a greater understanding of what the drug contains, but they may not be suitable for identifying newer compounds or adulterants and can tell you nothing about purity or strength. 
  • Prior to preparing ketamine, wash your hands and ensure the surface is clean – unclean surfaces such as toilets, phones and keys can spread disease. Use an alcohol wipe to disinfect surfaces before use.  
  • Use scales to measure the dose – you can’t judge an accurate dose just by looking. Start with a small dose and go slow! Remember, that the more of a drug you take, the riskier it is and the more likely you are to experience negative effects.  
  • You can’t judge content or purity by appearance – take a tiny test dose first. Purity can vary, even within batches. 
  • Avoid taking drugs alone and have a ‘sober’ friend around if possible.
  • Think about your setting – ketamine can affect your balance and coordination — only take it in a safe space avoiding dangers such as glass (including tables and doors), water (including rivers and lakes), heat (including cookers and radiators) and traffic. Be aware that as ketamine reduces your ability to feel pain, you may not realise how bad injuries are until the effects wear off. 
  • Plan your doses in advance – your perception of a dose once you are already high will not be accurateKetamine can also affect your perception of time  use a watch or timer to keep track of how frequently you are dosing leaving a minimum of 30 mins before each dose.
  • Only carry what you plan on taking. If you have a couple of grams in your pocket it is easy to take more than you anticipated. Leave what you don’t need at home (in a safe place).
  • Stay hydrated – drink a normal amount of water/isotonic drink for the activity you are doing. Try to avoid lots of fizzy drinks, especially those high in sugar. You probably don’t need any more than half a pint of water per hour unless you are in a busy, hot environment. 
  • Ketamine can seriously and permanently damage your bladder. Symptoms of urinary tract/ bladder damage include cramps, abdominal pain, difficulty urinating, frequently urinating and blood in urine. If you experience these symptoms, we recommend trying to reduce or stop ketamine use and seek medical help. Any route of administration can lead to this pain and damage.
  • Ketamine can make you feel sick — ensure anyone who has been taking ketamine and is sleeping (or is unable to move) is placed on their side to prevent choking in case they throw up. 
  • Be aware that if you experience vomiting this could reduce the effectiveness of the contraceptive pill – use alternative methods to avoid unintended pregnancy.   
  • Think about safe sex – grab condoms, dams and whatever else will help keep you safe depending on how you have sex. Ketamine can interfere with our decision-making abilities so it’s important to think about consent. Are you really feeling it? Are they? Ensure you have full consent before, and during, any sexual activity. 
  • If you start to feel any negative effects, simple things like changing your environment may help. If the effects are too strong, try to stay relaxed, control your breathing and take small sips of water or flat sugary juice. Let someone know how you are feeling – sometimes just sharing that feeling can help ease it.  
  • Look after your pals and seek medical help as soon as possible if needed. Be honest about what has been taken.  
  • Call 999 and ask for an ambulance if you see the signs of an overdose: confusion, unconsciousness (won’t wake with a shout or a shake), severe nausea and vomiting, fitting, difficulty breathing, snoring/raspy breathing, blue/pale tingeing of knees, hands and lips, slow or erratic pulse (heartbeat), pale, cold and clammy skin.
  • Always let medical professionals know if you have a history of ketamine use if they are going to be administering anesthetic or pain numbing drugs as ketamine tolerance can have an impact on how effective these are.
  • Some people may use ketamine to manage feelings of anxiety but for others regular use can increase anxious thoughts and reduce their ability to deal with them.
  • Ketamine might be used to block feelings of mental pain — it can then be difficult to break the cycle of re-dosing. If you are struggling to manage you drug use speak to a drug service in your area: 
  • If you have any health conditions that require timely medication e.g. diabetes, then take extra care to set reminders – see our drugs and diabetes guide for more info.


  • Drugs affect people differently and mixing different drugs can lead to unpredictable harmful and unpleasant effects. 
  • Avoid mixing different drugs including alcohol and medicines as this can cause dangerous, unintended or unpredictable effects. Take time to research possible interactions with your medication or health condition.  
  • Ketamine and alcohol is a risky combination as both can affect your coordination, balance, perception of pain and can reduce your breathing rate to dangerous levels. It will also increase the risk of being sick. 
  • Sleeping pills, benzos, heroin and GHB slow down your breathing and should be avoided. 
  • Mixing ketamine with cocaine can increase the risk to your heart. Cocaine can dull the effects of ketamine which could cause you take more of each drug to get the desired effect. This won’t improve your experience but will increase the risk to your health. 
  • Mixing ketamine with other drugs that produce a psychedelic effect, including LSD, MDMA, nitrous oxide and cannabis can heighten the psychedelic experience in a way that may feel overwhelming and be difficult to manage. 
  • If you do mix drugs, do your research, ensure you are somewhere safe and take way less of both substances than you would if you were only taking one.  
  • If you can’t avoid alcohol completely, try to limit yourself to only a few drinks, choose drinks with a lower alcohol content and drink water or soft drinks between alcoholic ones. 


  • Grind or crush ketamine down as fine as possible before use. This makes it easier to judge a dose, speeds up absorption into the body and reduces the damage to soft tissue from abrasion. 
  • Avoid using bank notes as a tool to snort drugs, as they aren’t disposable and can cut the inside of your nose — post-its or paper straws are a good alternative to notes.  
  • Sharing tools can spread infections and blood borne viruses (e.g. hepatitis C, HIV) – only use your own equipment. Get tested regularly for BBVs.   
  • Position the tool as high up the nostril as possible and alternate nostrils for each dose.  
  • Spiting out any powder which collects at the back of your throat (‘the drip’) may reduce overall harm but is not thought to reduce harm to your bladder 
  • Snorting can cause pain when swallowing, nosebleeds and recurring nose or throat infections. Rinse your nose out with clean water at the end of a session, to prevent the powder causing further damage to the inside of your nose. 
  • Apply a thin layer of vitamin E oil to the inside of the nose after rinsing.  
  • If you take ketamine on a regular basis, consider volumetric dosing which involves dissolving ketamine powder into clean water and administering in small doses like nasal spray. This can reduce damage to your nose. Care should be taken to measure the mixture accurately using scales and the container with the solution should not be left unattended. Pay attention to how frequently you are dosing if using this method.  


  • Grind or crush ketamine down as fine as possible before use. This makes it easier to judge a dose and speeds up absorption into the body.  
  • Swallowing ketamine is not a common route of administration as it does not give the same high as snorting but will still cause damage to the bladder. 
  • Dose low and wait 2 hours before re-dosing. It takes longer for the effects to come on if swallowed (compared to snorting or injecting).  
  • Use a new cigarette paper or gel capsule to “bomb” powder.  
  • If mixed into a drink, care should be taken to accurately dose and the bottle/cup marked to ensure no one else accidentally drinks it. Never leave your drink unattended and avoid drinking from bottles/cups if you are unsure of what’s in it.   

IF INJECTING  There is a higher risk of overdose if ketamine is injected. Injecting ketamine also risks causing soft tissue damage at the injecting site and this can cause life-threatening infections and abscesses. 

  • Only use new, sterile supplies. These are available from injecting equipment providers (IEPs or needle exchanges) or can be bought online.   
  • Ketamine is injected into the muscle (IM, intramuscular). Injecting into the muscle requires a bigger needle than injecting into the vein (IV, intravascular). Tell the staff at the IEP what drug you are taking so they can provide you with the most suitable equipment. If buying injecting equipment online, research the most suitable equipment.  
  • Sharing equipment including needles, filters, containers, spoons and water can spread infections and blood borne viruses (e.g. hepatitis C, HIV) – only use your own. Use colour coded equipment to avoid confusion and get tested regularly for BBVs. 
  • Follow good hygiene practice and wash your hands and injection sites (before and after). 
  • A smaller amount of ketamine will achieve the intended effects than snorting – reduce your dose. 
  • Citric acid, vitamin C and heat aren’t needed to dissolve ketamine and their use can increase harms. Ketamine powder/crystal can be dissolved in water.  
  • Once dissolved in water, it is important to use a sterile filter to remove non-soluble substances which can cause harms if injected.  
  • Keep the needle sterile and avoid licking the needle as this can transfer bacteria from the mouth into the skin and cause infections. 
  • Use a new needle each time – needles become blunt after one use.  
  • Rotate injection sites. Common IM injection sites are the thigh, bum, hip and upper arm. 
  • Dispose of equipment responsibly. It can be returned to an IEP.   
  • Seek medical help if the injecting site is painful, tender or hot, or there is swelling for more than a few days.   
  • Injecting ketamine does not reduce risk to the bladder and increases the risk of blood-borne virus transmission, infection and overdose. 

Detection time

People taking ketamine have reported the following detection time, but this cannot be taken as a recommendation; detection of any drug will depend on purity, regularity of use, other medications or drugs you have taken, your body and how it’s taken.
  • 1–5 days in urine