How Long Does Ketamine Stay in Your System?

People asking how long ketamine lasts usually mean the effects when you take it recreationally, and that high can be very short. When it’s snorted, ketamine’s effects come on within a few minutes, and the main effects fade within around 30 minutes to an hour. In general, the bigger the dose, the closer to an hour the effects last.

But you won’t usually feel completely back to normal the minute the effects fade. It’s normal to feel groggy or detached for a few hours afterwards, with the length and intensity of the comedown depending on how much you took that time and how much you take regularly.

Ketamine half-life is the time your body takes to clear half of the drug from your blood. Different drugs have different half-lives, and ketamine’s is around two to four hours, which means the drug itself is mostly out of your blood within a day, even after a big session.

However, your liver breaks ketamine down into ketamine metabolites, mainly one called norketamine and another called dehydronorketamine. These leave your body more slowly than the drug that made them. Tests look for the metabolites along with the ketamine itself.

A ketamine drug test usually means a urine test. Urine keeps traces longer than blood or saliva, and it costs less to check. A urine test is usually a simple sample in a cup, sometimes checked on the spot with a dipstick and sometimes sent to a lab for a more detailed panel. Standard workplace screens don’t always include ketamine, but any lab can test for it when somebody asks. If the test is part of a court order or a workplace policy, the paperwork usually says which type it will be.

Ketamine can generally be detected in urine for several days, but there is no single detection window that applies to everyone. How long it remains detectable depends partly on the type and sensitivity of the urine test being used. In one study, ketamine was detected for up to two days after a single dose using a standard testing method, while a more sensitive test detected it for up to 11 days. Norketamine, one of ketamine’s metabolites, was detectable for up to 14 days.

Your pattern of use can also affect how long ketamine remains detectable. Someone who uses ketamine regularly or in large amounts may continue to test positive for longer than someone who uses it occasionally. If you use ketamine most days, it is safest to allow for the longer end of the possible detection window.

Ketamine stays in blood for only a day or so after use, and not much longer. Blood tests are often used where timing is essential, like after an accident, and it needs to be known whether someone was under the influence. In England and Wales, driving with more than 20 micrograms of ketamine per litre of blood is an offence under the drug driving regulations.

But nobody should treat this limit as some kind of target to stay slightly under. Ketamine greatly affects your coordination and sense of where you are, and it’s never safe to drive on it, no matter how much ketamine you’ve taken.

Saliva tests can only read drug use in the last day or two, and they’re rare for ketamine in Britain. But hair is at the complete opposite end of the scale. A standard hair test reads about three months of growth, so ketamine can appear in a hair test months after your last use. Both of those windows are for general testing practices, not specifically for ketamine, so exact detection windows may vary.

Two people can take the same amount on the same night, and one tests positive days after the other is clear. The dose is one reason, but how often you use ketamine is really the main factor. Regular ketamine use gives your body a backlog to clear.

Your metabolism and your liver do the clearing, and anything that slows them, from age to liver damage to some medications, slows the whole timetable. Other drugs and alcohol also give the same liver more work, and everything clears more slowly.

The short answer is that you can’t. Water, exercise, saunas, and vitamins are all touted as possible shortcuts, but not one of them speeds your liver up.

Drinking lots of water dilutes your urine, and labs notice diluted samples and will probably just make you do another test or use a different testing method.

Exercise moves blood around, but your liver still works at its own speed. The myths survive because everybody who waits long enough tests negative eventually, whatever they did in between.