Ketamine is a controlled synthetic drug known in scientific and medical circles as a dissociative anaesthetic, which is firmly established as a sedative drug and anaesthetic for both human patients and animals in veterinary practice. (5)
Synthetic drugs such as ketamine are man-made drugs rather than drugs formed from natural sources on the planet.
Ketamine is a drug that contains several chemicals that can be extremely beneficial in the area of medicine, including:
Due to the positive psychological effects it generates, ketamine has also established itself as a recreational drug used frequently on the club and party scene. This is both as a drug on its own and mixed with other drugs and/or alcohol as part of polydrug use practices. (5)
Recreational users are keen to experience some of its effects to obtain positive emotions such as pleasure and calmness, to experience new perceptions (hallucinations) and sensations (e.g. floating) and escape reality by detaching from themselves, their everyday lives and their immediate environment.
Ketamine’s effects can be experienced within minutes and can last for several hours depending on how much of the drug has been taken.
However, it has been observed that people who have taken ketamine can experience problems with their balance and coordination and senses for around 24 hours after taking the drug. (5)
There is a difference between how long ketamine affects us and how long the drug stays in our system. We may feel that we are no longer affected by the drug but that does not mean that every trace of the drug is out of our system.
To help us understand this it is important to understand the half-life of ketamine.
All drugs differ in their chemical content, and this can lead to many differences in how the drug affects the human body, how long it takes to cause an effect and how long it remains in our system.
An important point to understand is the half-life of the drug. A drug’s half-life refers to the amount of time it takes the body’s metabolic system to eliminate half of the drug from the human body.
Drugs with a short half-life tend to produce more intense withdrawal symptoms than drugs with a longer half-life and are considered more addictive.
This is because drugs with shorter half-lives will eventually need to be taken at shorter time intervals to keep withdrawal symptoms away when a person becomes dependent on the drug.
A close look at ketamine’s chemical structure shows that the drug has a half-life of around 45 minutes to one hour. It is commonly assumed by scientists that all drugs require 5 half-lives to be eliminated from the body.
This means that overall it takes a minimum of 4 hours for ketamine to be eliminated from the body once it has been taken, although it may take longer for some people. (3,5)
However, science is never that simple and even though ketamine appears to be eliminated from a person’s system, traces of the drug and its effects remain imprinted on aspects of our internal physiology for longer.
These traces can be detected by several medical technologies which will be discussed later on.
The key process in the human body that determines how long ketamine remains in the body is metabolism, which is achieved through a biological process that breaks down the drug so it can be removed from the body.
The liver has a high amount of key enzymes which are important for breaking down ketamine and transferring them into another chemical form which enables the drug to be removed from our body quickly and efficiently.
Metabolites are the result of internal chemical interactions and processes that occur when key enzymes in the liver begin to break down ketamine.
Even though all of the ketamine that has been taken may have left the body, the chemical interactions within the liver that take place when ketamine is processed form a new substance called metabolites.
Even though all of the drug may have left the system the presence of these metabolites can still be traced and provide scientific proof that a person has consumed ketamine within the last few weeks/months. (3)
Scientists use the term excretion to describe the process of eliminating drugs from our bodies.
The body and brain work together to minimise the effects of any substance that is consumed to ensure that people who take drugs like ketamine can carry on with their daily activities lives without being hampered by the effects of the drug. (3,5)
Ketamine is metabolised by the liver and the result of this process generates metabolites called norketamine and dehydronorketamine. These metabolites help to break down ketamine into a chemical form that is transferred around the body to be removed through our urine and breath.
Approximately 90% of the ketamine that is taken is excreted through urine and the remaining 10% is removed through our breath. (3,5)
Even though ketamine can be eliminated from the body in 4-15 hours, traces of ketamine can be detected for much longer.
This is because the metabolites generated by the metabolic process are absorbed into our tissues and cells and remain there for far longer, even if the last ketamine dose we consumed has left our system and is no longer affecting us.
Many organisations are keen to eradicate drug misuse from their business as it can damage their reputation and lead to a decline in productivity. This is because, in many areas of employment, drugs can have a negative effect on employees that carry out important roles and can have catastrophic consequences.
For example, employees that have job roles relating to driving, operating machinery, looking after children’s welfare or performing at a high level in a particular sport can be negatively impacted by ketamine use.
Consistently taking ketamine can have both short and long-term effects or users that can impact on many aspects of their lives.
Such is the prevalence of substance use that many employers feel they must screen their employees for drug use to safeguard against any negative consequences for their organisation.
Companies may have different procedures for dealing with issues relating to substance use which all employees will be warned about. Some companies could have a zero-tolerance policy whereas others may issue employees with one or two warnings before dismissal.
Some companies organise regular drug testing appointments for employees whereas others may spring random drug tests on their employees. (2,4)
People taking ketamine for medical purposes need not have any worries about how long ketamine is present in their system as they have a legitimate reason for taking the drug which most employers, organisations and law enforcement agencies should understand.
It is guaranteed that the precise dose strength of medical ketamine that patients are taking will be clearly stated along with other chemicals present in their medication.
It is very hard for recreational users to pinpoint exactly how much ketamine they have taken as it is virtually impossible to measure the strength of ketamine doses that are obtained illicitly. Because of this it is difficult to predict how long ketamine will remain in their body. (3,5)
Even though scientific analysis reveals that it takes a minimum of 4 hours to remove ketamine from the body, this isn’t necessarily the case for everyone. This is because there are many factors that determine how long it takes ketamine to leave the body.
These include:
All recreational users have different patterns of ketamine use that can affect how long the drug stays in their system. This includes the dose strength, how often they take ketamine and how long they have been taking it.
It is unlikely that someone who regularly takes ketamine will be unable to hide it from any drug test. In order for there to be no traces of ketamine detectable in your system you need to avoid taking ketamine for 3-4 months.
How much water an individual regularly drinks can significantly affect how long ketamine will remain in their system.
Individuals who hydrate their bodies frequently will find that the body’s metabolic system will be able to remove ketamine more quickly from their bodies than individuals who do not.
Drinking water regularly helps to flush out the toxic properties of ketamine from all human tissue and aids with the metabolic and drug elimination process. (3)
Children and older people will be much slower at processing and eliminating ketamine from their system than healthy adults in the 20-60 age range, who will have the physiological efficiency to remove ketamine more rapidly. (2,3)
Overall women have less body mass compared to men and will be more affected by the chemical contents of psychoactive drugs. If men and women consume the same dose strength of ketamine, traces of the drug will take longer to leave the female body as men do tend to metabolise drugs much more quickly.
People who weigh less, on the whole, will have a faster metabolism and this will ensure that ketamine is processed and removed from their body more quickly than people who have a higher BMI.
Ketamine is a lipophilic drug which is easily absorbed into fat. So taking high doses of ketamine increases the chances of its metabolites being transferred to fat stores throughout the human body where they can remain for months and will show up on drug tests.
Every person is unique in terms of their individual biology and it is hard to say with any certainty who will be more affected by ketamine and who will be able to eliminate the drug quicker from their bodies.
There are a whole host of physiological processes happening inside us that determine how quickly we can eliminate ketamine from our body linked to digestion, blood flow, lung function, metabolic process and liver efficiency to name but a few. (5,6)
The body of a person in good physical health who eats healthy meals and exercises regularly will be able to break down the chemicals found in ketamine and eliminate the drug from the body far more quickly than an unhealthy person.
The liver and kidneys are vital organs in the human body for breaking down drugs and removing them from the body as waste products.
For the body to efficiently eliminate ketamine from the body the liver and kidneys must be in optimal condition.
If this is not the case, then the process of removing the drug from the body will become somewhat laboured and take significantly longer.
Anyone on medication whilst taking ketamine may find that it will take longer for the ketamine to leave their system. This is because some prescription drugs are capable of restricting the effectiveness of certain enzymes that are essential for metabolising ketamine.
Anyone who engages in polysubstance use will also find that ketamine will remain in their system for longer as the body (and in particular the liver) have to work extra hard to break down all the psychoactive substances (including alcohol) that are being consumed.
This puts extra pressure on the liver and will lead to an overall decline in health if polysubstance use is sustained for too long. This will further reduce the body’s ability to metabolise and eliminate ketamine from the body.
However, the more often ketamine is taken or combined with other substances the more damage could be done to the liver and kidneys, placing the person’s health at even greater risk. (3,4)
Drug testing informs us whether a person has consumed a drug in the recent past or not. It can be very difficult to eliminate all the evidence of ketamine use.
This is because the metabolites that are generated during the process of breaking down ketamine remain detectable in the body for several weeks if not months even though the ketamine has left our body.
The presence of these metabolites proves that a person has consumed ketamine recently because there is no other reason that accounts for their presence.
There are a range of scientific tests available that can establish if ketamine is still in our system after being consumed, with some of the scientific tests being more sophisticated than others.
The main tests used for drug detection are:
Scientists using a standard urine test have been able to identify the presence of ketamine in a person’s body for up to 6 days after consuming the drug. The more sophisticated tests can pick up traces of ketamine 2 weeks after the drug has been taken.
People who have been taking higher amounts of ketamine for a long time will find that ketamine can be detected in their urine several weeks after they last took the drug. People who do not take ketamine often will find that a urine test will only be able to detect the presence of the drug for a couple of days after use.
The saliva test is only able to determine if ketamine has been consumed for 24-48 hours after the drug was taken. This is a useful test to use on people who have jobs in driving or operating machinery to assess if they may still be under the influence of ketamine.
Blood tests to search for traces of ketamine in a user’s bloodstream can be detected for up to around three days after the drug was ingested.
However, blood tests are more invasive and uncomfortable procedures for many people and are considered time-consuming and expensive to implement. Blood tests are not commonly used for ketamine detection.
The most sophisticated test for detecting any signs of ketamine in the human body is the hair strand test. Technological advances have developed testing techniques that can pinpoint the presence of ketamine in human hair up to four months after they consumed the drug. (1,2,6)
So, despite not taking the drug for several months, it is possible for scientific techniques to ascertain that someone has taken the drug in recent months even though they may not have consumed the drug recently.
Advances in drug science and testing methods have led to a greater understanding of how ketamine affects the human body and central nervous system.
There is also a greater understanding of how the body breaks down the ketamine once ingested and begins the process of removing the psychoactive drug from the body.
There are several processes along the way that provide clues to indicate ketamine use (e.g. metabolites) despite the person not being affected by the drug anymore.
(1) Abbott (2019) Toxicology: Windows of Detection. Available@https://www.aleretoxicology.co.uk/en/home/support/testing-explained/windows-of-detection.html
(2) Brodwin, E., Radovanovic, D. (2018) How Long Common Drugs Stay in Your Body
Available at https://www.sciencealert.com/here-s-how-long-drugs-stay-in-your-body-weed-cocaine-MDMA-science
(3) Moss, A.C. & Dyer, K. (2010) The Psychology of Addictive Behaviour. Palgrave McMillan. Basingstoke.
(4) National Institute on Drug Abuse (2019) How Science Has Revolutionized the Understanding of Drug Addiction available at.https://www.drugabuse.gov/publications/drugs-brains-behavior-science-addiction/preface 1
(5) Rosenbaum, S. et al (2022) Ketamine. National Library of Medicine. available@Ketamine – StatPearls – NCBI Bookshelf (nih.gov)
(6) Sussex Partnership NHS (2017) Guide to how long substances and drugs of abuse may be detected in the body after last use Available at https://web.archive.org/web/20211209201517/https://www.sussexpartnership.nhs.uk/sites/default/files/documents/illicit_drug_screen_times_-_jan_17.pdf
Boris is our editor-in-chief at Rehab 4 Addiction. Boris is an addiction expert with more than 20 years in the field. His expertise covers a broad of topics relating to addiction, rehab and recovery. Boris is an addiction therapist and assists in the alcohol detox and rehab process. Boris has been featured on a variety of websites, including the BBC, Verywell Mind and Healthline. You can connect with Boris online at LinkedIn or X.com.
