Ketamine is a powerful anaesthetic that is used in medical and veterinary practices as well as an antidepressant alternative for those suffering from depression. It is also used illicitly as a hallucinogenic drug. Ketamine has a relatively short-half life yet traces of the drug can stay in the system for a long time. Read below to find out more about ketamine detection times in the body.

What is The Half-Life of Ketamine?

Ketamine has a half-life of approximately 45 minutes, meaning the drug is processed by the body very quickly and its effects do not last long. The effects and half-life of the drug are increased when more of the substance is taken.

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How long does ketamine stay in your system?

The effects of taking Ketamine can often be felt within 30 minutes of taking the substance and will often have subsided after an hour. Despite the drug's quick onset and decline of effect, ketamine can still be detected in the system long after use. Below is the average detection time of ketamine by drug type. 

Test type Detection period
Urine
up to two weeks
Blood up to four days
Saliva N/A
Hair up to 90 days

Traces of ketamine stay in the body for a long time, making it easy to appear on most drug tests. However, due to the nature of the substance and how it is absorbed by the body, it doesn’t show up well if at all in saliva tests. 

The length of time ketamine is detectable in the system can vary from person to person and by how much of the drug has been consumed prior to testing.

Read here to find out more about detection times for drugs and alcohol. 

Factors that affect ketamine metabolism rates

There are many factors that can influence the detection rate of ketamine in a toxicology test and these can vary from person to person. 

Factors that influence ketamine detection rates include:[1]

  • Length of time ketamine was taken for

  • Quantity of ketamine taken

  • Dose strength

  • Whether other substances were taken (such as alcohol or other stimulants) 

  • Body mass index (obese people will take longer to process substances)

  • Gender

  • Age 

  • Pre-existing medical conditions (especially those involving the liver or kidneys)

As ketamine is mainly excreted through urine, someone who is well hydrated will often pass ketamine more quickly than someone who isn’t. Additionally, those with a high metabolic rate will often process substances like ketamine quickly, meaning the drug will be eliminated from the system faster.

False-positive results from ketamine

While drug testing for ketamine is uncommon, case studies have shown that ketamine analogues can cause false-positive phencyclidine (PCP) immunoassay results.[2] This means that someone who has taken ketamine, even the medical version esketamine (Spravato), may have a positive result for PCP. 

As PCP is an illicit substance, those who have a false-positive result for the substance may face jail time. It is important to notify the person taking the test if you have taken ketamine recently in order to prevent a mistake from being made if ketamine or phencyclidine analogues are detected.