Ketamine stays in the body for a relatively short time, but detection windows vary depending on the type of test and individual factors. Half-life and elimination:

• Ketamine has a half-life of about 2.5 to 3 hours, meaning half the drug is eliminated in that time. It generally takes around 10 hours (4-5 half-lives) for ketamine to be mostly cleared from the body

• Some sources note a shorter half-life around 45 minutes, with total elimination in about 3-4 hours, but 2.5 hours is more commonly cited

Detection times by test type:

• Blood: Ketamine can be detected for up to 24 to 48 hours after use

• Urine: Ketamine and its metabolites can be detected for anywhere from 3 days up to 2 weeks or even 30 days in some cases, especially with higher or chronic use

• Saliva: Ketamine is detectable for about 24 to 48 hours after use

• Hair: Ketamine can be detected in hair follicles for several months, typically up to 90 days or more, because metabolites are trapped in hair as it grows

Factors influencing detection time:

• Dosage and frequency of use (higher or repeated doses prolong detection)
• Individual metabolism and health
• Type of test and its sensitivity

In summary, ketamine's effects last minutes to an hour, but the drug and its metabolites can be detected in the body for days to weeks depending on the testing method. Hair tests can reveal use for months after the last dose