person opening bag of ketamine
Photo by Georgia Love for DoubleBlind

How Long Does Ketamine Stay In Your System?

It might be longer than you think.

DoubleBlind Mag

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Published on
Updated December 18, 2023

Ketamine is a dissociative molecule with a story that begins in the clinic. Originally developed as an anesthetic in the 1960s, ketamine eventually leaked into the outside community, where its dreamlike, out-of-body effects were embraced, especially in circles of club and festival goers. As research began to unveil the antidepressant potential of this Schedule III drug, ketamine expanded its foothold in the clinic, this time as an agent of psychological change among patients experiencing treatment-resistant depression. Studies still measure ketamine’s risks, safety, and efficacy for psychiatric conditions. Still, clinicians across the U.S. are steadily opening their minds to the treatment and doors to interested patients. 

“In my practice, and in the way that I teach ketamine-assisted psychotherapy (KAP), ketamine is a partner to the healing process,” explains Lauren Taus, a licensed clinical therapist focused on psychedelic integration and ketamine-assisted psychotherapy. “In psychedelic dosing, a person can expect to experience a ‘journey,’ a true interruption of ordinary mind in a safe way that can elicit a wide range of experiences that create powerful perspective shifts, a proverbial widening of the aperture, and perhaps a ’system upgrade.’”

Despite its expanding acceptance and clinical availability, ketamine sits within complex social and legal landscapes. While it may have therapeutic utility, ketamine is not without risk—especially outside the care of a trained professional. It can cause some side effects, and it’s possible to develop a dependent relationship with its dissociative qualities. Also, employers and other entities still hold the legal right to drug test for ketamine. So how long does the body hold onto ketamine’s chemical footprint? And what can you expect in the days after taking it?

hand holding bag of ketamine
Photo by Georgia Love for DoubleBlind

How Long Does Ketamine Stay in Your System?

There’s really no short, simple TL;DR explanation for how long ketamine stays in your system. Generalizations tend to skimp on essential nuances. Many different factors can influence how long a ketamine experience lasts and how long it takes for your body to clear the substance from your system. The Mayo Clinic suggests that ketamine may remain detectable in blood plasma for up to two days. Although, it may take longer depending on your dose and other variables. With repeated doses, ketamine may stay in your system for as long as 11 days, studies suggest.

The Mayo Clinic suggests that ketamine may remain detectable in blood plasma for up to two days. Although, it may take longer depending on your dose and other factors.

The active effects of ketamine vary depending on how a person consumes the drug. The ketamine experience can last between 60 and 90 minutes when taken orally. Intravenously, 20 to 60 minutes. These numbers may change from person to person, however. Factors like dosage, individual metabolism, and other confounding variables can affect how long the drug’s active effects last.

Half-Life of Ketamine

The human body clears different substances at different rates. One term to understand when talking about the presence of a drug in the body is half-life. Elimination half-life refers to the time it takes for a drug’s concentration to decrease by half in the body (in blood plasma, in particular). The elimination process can range between hours and weeks depending on the drug and how an individual’s body processes it. Some substances—like cannabis—have relatively long half-lives. Loosely speaking, cannabis can take up to two weeks—or longer—to leave your system.

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Ketamine is different—and complicated. Its half-life changes depending on how the drug was administered. Most ketamine and its metabolites leave the body within 12 hours for most people using intravenous (IV) administration, which is commonly used in ketamine clinics. Yet, “most” does not mean “all.” The half-life may change with other routes of administration—along with the many other factors discussed below. High doses taken through the nose, for example, may stay in your system longer.

A person may still feel some residual or trace effects of ketamine for the day following their last dose or treatment. “Depending on how that person metabolizes the drug, they might just feel out-of-it for a little bit, or it might be the whole rest of the day,” says Dr. Lauren Zelfand, a licensed family physician who provides consultation and treatment involving ketamine. “Just rest and let your nervous system catch up with what just happened and let your body metabolize the medication.”

It’s important to mention that giving a precise half-life for ketamine is challenging. A drug’s half-life is based on a formula that factors in two variables: clearance (how fast your body metabolizes and eliminates a drug) and volume of distribution (how much a particular drug tends to redistribute from plasma to other tissue). Pharmacokinetics, or the study of how a drug moves throughout the body, is a long and winding rabbit hole to fall down—one that’ll show you just how complicated detection can get when you consider the many factors of influence.

vial of ketamine
Photo via Wikimedia Commons

Factors that Influence How Long Ketamine Stays In Your System

The liver is your body’s first detox center. Enzymes in the organ chemically break down drugs like ketamine so that the body can remove them properly. Once metabolized, most ketamine leaves your body in urine, a process facilitated by your secondary detoxification organs: the kidneys. Yet, how long your body needs to eliminate a detectable amount of ketamine from your system depends on many variables. Here are a few things to consider:

Dosing: Although the rate at which your body eliminates ketamine is consistent, larger doses of ketamine will take longer to process. 

Route of administration: There are many different ways to take ketamine, and every method comes with a unique elimination time frame. 

“I don’t know if you’ve seen the movie Forrest Gump, that scene where Bubba is talking about all the different ways to make shrimp,” says Dr. Zelfand. “It’s sort of like that with ketamine.” 

Channeling Bubba, Dr. Zelfand rattles off a list of different ways to deliver ketamine:

  • Injection into a vein, under the skin, or into the muscle
  • Orally administered capsule
  • As a troche or lozenge dissolved in the mouth
  • Rectally administered using a suppository
  • Intranasally with a compounded spray
  • Topically as a cream for localized pain

READ: Ketamine Dosage: How Much is OK and How Much is Too Much?

Other factors that potentially impact ketamine’s retention and elimination include (but are not limited to):

  • Age: Younger individuals may eliminate ketamine faster than older adults.
  • Metabolism: Those with faster metabolic rates may eliminate ketamine faster.
  • Organ function: Individuals detox drugs at different rates depending on kidney and liver function. 
  • Frequency of use: Greater doses slow down the elimination process and increase the detection window. 
  • Sex differences: Biological females may eliminate ketamine faster than males.
  • Liver enzyme makeup: Different genetic versions of certain liver enzymes can increase or decrease elimination half-life. 
  • Medication interactions: certain medications may increase the elimination half-life through competition. 

Ketamine Drug Test

Given its controlled status, employers and other agencies are legally allowed to drug test for ketamine. There are a few different ways to drug test, including urine, blood, saliva, and hair analysis. But, drug screening for ketamine isn’t commonplace. Taus raises the point that 5-panel or 10-panel urine screenings—the most common type of drug test—don’t test for ketamine. “A drug screen for ketamine can be specifically ordered, but is not done so on routine analyses,” she said.

Still, it’s worth being careful about what substances you use if you choose to use them. A 2017 case study suggests that ketamine—along with ibuprofen and several other drugs—may falsely present as PCP on a standard five-panel urine drug screening.

In Taus’ perspective, workplace drug testing can open up a valuable forum with employers about psychotherapy-assisted treatments. “A conversation around the benefits of ketamine-assisted psychotherapy may be a good way to educate employers and support the destigmatization of [ketamine] as a healing modality.” Although conversations like this can certainly be risky—there’s no telling how someone will react or if this information.

Dr. Zelfand told DoubleBlind that patients can also try to defend their prescribed use of ketamine. “Patients have a right to privacy around those things, but that’s where a letter written by a prescriber to their employer could be helpful,” she said.

How Long Does Ketamine Stay in Your Urine?

Generally speaking, the body eliminates ketamine relatively quickly, which will usually be undetectable in urine between 12 hours and two days. Again, this window may be longer depending on the urine test, frequency of use, and other factors above.

Tests from different providers can have varying degrees of sensitivity. Urinalysis from Laboratory Corporation of America, a company that offers diagnostic and drug testing, has a 600 ng/mL cutoff. Forensic testing, used by police departments and other institutions to test samples of illicit drugs, can detect down to 50 ng/mL.

How Long Does Ketamine Stay in Your Blood?

Blood tests for ketamine are less common than urine since they’re invasive, expensive, and require a medical professional to extract a sample. As mentioned above, the Mayo Clinic suggests that ketamine and its metabolite, nor-ketamine, have a two-day detection window in blood plasma—but it really depends.

Ketamine Side Effects and Aftercare

Even though ketamine does not stay in your system for long, traces of its physical and emotional impact may persist longer. Zelfand and Taus both urge diligent self-care following a ketamine experience for this reason.

Taus says that clients undergoing ketamine-assisted psychotherapy rarely have a physical “hangover,” but among those who do, it’s typically a feeling of fatigue, headache, nausea, or brain fog.

“Some will feel more vulnerable, and a heightened state of emotion,” Taus said, “As a therapist, I will always encourage clients to give themselves ample space to sit with the experience after its completion, to give the experience the honor of attention as a means to integrate the information that presents.” Taus emphasizes the essentials of rest, hydration, and nutrition—and adds that meditation, nature, long baths, music, art, and movement can further support your landing after a powerful experience.

person with bag of ketamine
Photo by Georgia Love for DoubleBlind

“In the 24 hours after a session,” explains Taus, “some people experience a significant reduction in symptoms of anxiety and depression, a newfound sense of confidence, hope, courage, and love. These benefits can continue into the coming weeks, especially when the work is supported with active therapy.“

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Zelfand told DoubleBlind that patients are encouraged to attend a counseling appointment with a therapist well-versed in psychedelic integration no later than a day or two after the ketamine treatment. That way, they can take full advantage of ketamine’s neuroplastic opportunity—or its ability to stimulate changes in the brain—and receive support for challenging emotions that can arise.

READ: Does Ketamine Have a Dark Side?

“Because ketamine is dissociative, it [can push some clients] in the direction of despair and suicidality,” Zelfand said. “It’s not common, but I have seen it.” Research suggests that ketamine may reduce acute suicidal ideation in some individuals. Still, Zelfand highlights that these profound altered states of mind can affect us in complex and unique ways—and not always in the direction of our expectations.  

“It bears mentioning that some people experience an acute worsening of symptoms, often attributable to encountering difficult content in a journey,” Taus explains, “but a difficult experience isn’t necessarily bad and can sometimes serve as a catalyst for much-needed healing.”

Aftercare is important—and so is preparing an intentionally supportive container for the ketamine experience. Safe, trusting relationships allow us to explore bravely, and when ketamine launches you into uncharted depths of consciousness, the presence of a caring and trusted professional can offer a reassuring tether. 

“There are many direct-to-consumer companies providing the medicine without therapeutic support,” Taus said. “Being cared for while engaging in ketamine as a growth tool is an essential part of what makes this intervention a therapeutic and healing one.”


In the event of an emergency, please dial local emergency services. For mental health services in the US, dial 988. For substance abuse help in the US, please dial the Substance Abuse and Mental Health Services Administration National Helpline at +1 (800) 662-4357.

This article is intended for harm reduction purposes and should not be used in place of medical advice. DoubleBlind does not advocate participating in illicit activities. Always consult your local drug laws before engaging with illict substances.

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DoubleBlind is a trusted resource for news, evidence-based education, and reporting on psychedelics. We work with leading medical professionals, scientific researchers, journalists, mycologists, indigenous stewards, and cultural pioneers. Read about our editorial policy and fact-checking process here.

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DoubleBlind Magazine does not encourage or condone any illegal activities, including but not limited to the use of illegal substances. We do not provide mental health, clinical, or medical services. We are not a substitute for medical, psychological, or psychiatric diagnosis, treatment, or advice. If you are in a crisis or if you or any other person may be in danger or experiencing a mental health emergency, immediately call 911 or your local emergency resources. If you are considering suicide, please call 988 to connect with the National Suicide Prevention Lifeline.

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