How Long Does Ketamine Stay in Your System After Last Use?

Many Americans had never heard of ketamine until the death of “Friends” star Matthew Perry.[1] The medical examiner reported that Perry had been receiving “ketamine infusion therapy” for depression but accidentally overdosed, with more than a typical therapeutic dose found in his bloodstream.[1]

Although his death was later determined not to be directly caused by his therapy, public interest grew quickly. Many wanted to know why ketamine was found in his bloodstream after his death, if it was not the cause. People also searched for answers to questions such as “What is ketamine?” and “How is ketamine used for depression?” Unfortunately, many of these searches reveal conflicting answers, making it difficult to separate fact from speculation.

This blog will explain the uses of ketamine, how long it stays in your system after your last dose, and how long it can be detected on a drug test.

What Is Ketamine?

Ketamine is a drug classified as a dissociative anesthetic.[2] It has hallucinogenic effects and can distort a person’s perception of sight and sound, often leaving them feeling disconnected from reality. It is called a dissociative anesthetic hallucinogen because it can make patients feel detached from both their pain and their surroundings.[2]

In medical settings, ketamine is approved as a short-term anesthetic and is typically administered by injection.[3] It induces rapid sedation, which some describe as euphoric, although patients generally do not remember events that occur while under its influence. Unfortunately, this memory loss is one reason ketamine has been misused to facilitate sexual assault.[2] It is also used for pain relief.

A prescription form of ketamine, Spravato (esketamine), is available as a nasal spray for individuals with treatment-resistant depression.[2]

On the streets, both medical and illicit forms of ketamine are known by names such as Cat Valium, KitKat, Purple, Special K, Vitamin K, and Cat Tranquilizer.[2] Illicit ketamine is often adulterated and may be mixed into liquids or powders that can be snorted, smoked, or injected.

While under the influence, users may see, hear, or feel things that are not real. They may become agitated or depressed, experience memory problems, or lose consciousness. In some cases, individuals develop hallucinogen persisting perception disorder (HPPD), a condition that causes visual disturbances for weeks after ketamine use.[4]

What Is the Elimination Half-Life of Ketamine?

To understand how long ketamine stays in the body, it is important to first look at its elimination half-life. The elimination half-life is the time it takes for 50% of a medication to be naturally cleared from the system.

According to StatPearls, ketamine given through intravenous administration has an elimination half-life of about 2 to 4 hours.[3] During this time, ketamine and its metabolites are excreted through urine. There is no data on the elimination half-life of ketamine taken in adulterated or abusive forms, because it is typically used only in controlled medical settings.

When administered as a nasal spray, ketamine (called esketamine) has a longer elimination half-life of 7 to 12 hours.[5] This form is prescribed to help individuals with treatment-resistant depression.

How Long Does it Take Ketamine to Leave the System Completely?

According to the authors of a study published at StatPearls, it typically takes about 4 to 5 half-lives for 94% to 97% of a drug to be eliminated from the body, which is considered effectively cleared.[6]

Since esketamine has an elimination half-life of 7 to 12 hours, it may take approximately 28 to 48 hours on the shorter end and 35 to 60 hours on the longer end for the drug to entirely leave the system. This means it will no longer be clinically effective, though it may still appear on a drug screening because of its leftover metabolites.

What Factors Increase Ketamine’s Elimination Half-Life?

Some patient populations may experience a longer or shorter elimination half-life for ketamine than average. These include:[3]

• People with impaired liver function 
• Individuals with renal (kidney) impairment
• Older adults
• Pediatric patients

Those with liver or kidney impairment may have difficulty eliminating the drug efficiently and could require dosage adjustments. However, the U.S. Food and Drug Administration (FDA) does not provide specific dosing guidance for these situations, so physicians must proceed with caution.

Children have been found to metabolize ketamine more quickly than adults and will require higher doses for effectiveness. In contrast, older adults metabolize the drug more slowly than younger adults and may need lower doses to ensure safety.

What Side Effects Are Experienced During Ketamine’s Half-Life Elimination?

Ketamine can cause confusion and a dreamlike feeling.[7] Users may feel dizzy or drowsy for many hours after waking up from anesthesia and may have trouble thinking clearly. It is also possible to experience unusual thoughts or behaviors and to hallucinate afterwards.[7]

However, it is also possible to develop more serious side effects while under the influence of ketamine. The effects of ketamine include:[7]

• Bloody or cloudy urine
• Bluish lips or skin
• Changes in vision
• Burning during urination
• Chest pain
• Confusion
• Coughing
• Dizziness
• Difficulty swallowing
• Fainting
• Fast heart rate
• Frequent urination
• Hives or itching
• Irregular breathing
• Loss of vision
• Sweating

If you experience any of the above side effects, contact your healthcare provider immediately.

How Long Is Ketamine Detectable on a Urine Drug Test?

Although your body will eliminate most of the ketamine within a few days, it can still be detected through specialized drug screenings. Traditional five-panel and six-panel drug tests do not screen for ketamine, so ketamine will not appear on these tests. However, 20-panel tests and tests specifically designed for ketamine can detect the drug and its metabolites.[8]

Ketamine and ketamine metabolites can usually be detected in urine for 2 to 4 days.[8] However, people who metabolize the medication more slowly may still test positive several weeks later.

How to Know if Someone Is Addicted to Ketamine

Ketamine has shown promise in the medical field, particularly for individuals with treatment-resistant depression. However, using this medication in ways it was not prescribed or using it after obtaining it without a prescription can lead to serious health problems and addiction.

Individuals abusing ketamine may display several signs, including:

• Erratic behavior
• Trouble concentrating
• Mood swings
• Slurred speech
• Difficulty holding objects
• Problems with coordination
• Short-term memory loss
• New or worsening financial issues
• Neglecting responsibilities

Ketamine addiction is dangerous and can affect every part of a person’s life, including their mental health, physical health, and social well-being. Getting help for ketamine addiction is the most effective way to overcome it and reduce the risk of overdose or relapse.

Drug addiction treatment options may include:

• Medically supervised detoxification (detox) to ease withdrawal symptoms
• Therapy and support to address underlying issues that contributed to ketamine use
• Guidance in developing healthy coping mechanisms for managing stress during and after treatment
• Addressing co-occurring disorders, such as anxiety or depression
• Creating a relapse prevention plan to reduce the risk of returning to ketamine use

Seeking professional help for ketamine abuse is not a sign of weakness. It is the most productive step toward returning to a healthier, happier life.

For more information or assistance, contact Southeast Addiction Center today.