How Long Do Ketamine and Esketamine Stay in Your System?

Introduction

Many people considering treatment with ketamine or esketamine, or those already receiving either treatment, wonder how long these medications stay in their body. This is a common question, whether the concern is about how long the benefits last, how quickly the side effects wear off, or whether the medication might appear on a drug test.

Ketamine and esketamine are used under medical supervision of interventional psychiatrists for depression. While their therapeutic effects may extend well beyond the short time the drug is active in the body, the actual clearance happens relatively quickly. Knowing how the body processes these medications can help set expectations and provide reassurance about their safe use.

How the Body Processes Ketamine and Esketamine

Once ketamine or esketamine enters the body, the liver quickly begins breaking it down. Specialized enzymes process the medication into byproducts, the most notable being norketamine, which can remain in the system after the original medication has been metabolized.

In clinical practice, IV ketamine is typically infused over about 40 minutes directly into the bloodstream. Esketamine (Spravato®) is delivered as a nasal spray, is quickly absorbed into the bloodstream and reaches peak levels around a similar time frame, though with slightly more variability between individuals.

The original medication is present in the body only for a relatively short time, with the natural metabolism continuing to eliminate it over the following hours after administration.

Half-Life and Duration in the Body

A key way to understand how long a drug stays in the body is by looking at its half-life: the amount of time it takes for the concentration of the drug in the bloodstream to decrease by half.

For ketamine, the half-life is typically about 2 to 3 hours. Esketamine has a somewhat longer half-life, usually about 7 to 12 hours. After several half-lives, only trace amounts remain, meaning that within about a day the original medication has largely cleared the system.

How Long Do Ketamine and Esketamine Stay in Your System?It’s important to note that for ketamine and esketamine, the presence of the medication in the body is not the same thing as how long its therapeutic effects last. The immediate sedative and dissociative effects fade within hours, while the antidepressant benefits can continue for days to weeks. This is an interesting and fortunate property of these medications: even though the body processes ketamine and esketamine fairly quickly, the positive impact on mood may extend well beyond the period the medication itself is present.

Drug Testing and Detectability

Another common question is whether ketamine or esketamine could show up on a drug test. In general, neither is included in most standard workplace drug panels, including the common 5-panel or 12-panel drug tests which typically focus on substances such as opioids, cannabis, cocaine, and amphetamines. However, specialized toxicology testing can detect ketamine or esketamine if specifically requested.

When tested, the approximate detection windows are:

• Blood: 1–3 days

• Urine: 1–2 weeks

• Hair: up to several months

These time frames can differ depending on medication frequency, dosage, and each person’s metabolism.

For people receiving ketamine or esketamine as indicated and under medical supervision, these detection windows generally do not affect routine employment testing. Still, if a specialized test is required (for example in a legal, forensic, or competitive sports setting) it is best to let the testing provider know about prescribed treatment so results can be interpreted in the proper context. If you have concerns about testing or detection, discussing them directly with your provider can give you clear guidance for your situation.

Clinical Relevance for People Receiving Treatment

While it can be helpful to understand how long ketamine or esketamine stays in the body, the more practical question for most people is what this means for their treatment and day-to-day life.

The original medication is cleared from the system within days, but the therapeutic effects often last much longer. This property of ketamine and esketamine is critical in allowing treatment to be done twice a week at the beginning, then be spread even further to once a week and longer for those responding to the treatment. This difference between drug clearance and symptom relief highlights why these treatments are carefully monitored in medical settings.

Side effects such as dizziness, dissociation, or changes in blood pressure are typically short-lived and fade within hours, which is why for esketamine, people are monitored in clinic for at least two hours after each session to ensure safety before going home. With IV ketamine, a similar period of monitoring is standard. Importantly, these medications do not accumulate in the body when used as prescribed, so repeated treatments remain safe under supervision.

Overall, the presence of ketamine or esketamine in the body is brief, but the benefits can extend well beyond the short window of drug activity. Understanding this can ease concerns about safety, daily functioning, and longer-term use.

Conclusion

Ketamine and esketamine remain in the body only for a short period, usually days at most, though they may be detectable for longer on specialized drug tests. However, benefits often continue well beyond the time the medication itself is present, providing meaningful, long-term relief from symptoms of depression and related conditions.

When used under expert supervision, these treatments are safe, carefully monitored, and do not build up in the body over time.

If you believe ketamine or esketamine treatment may be right for you or it has been suggested to you by your mental health provider, feel free to contact us to schedule an evaluation. Our team can help you explore whether this approach is a good fit for your needs and guide you through the next steps.