What Is A Lethal Dose Of Ketamine?

Ketamine is a short-acting anesthetic. It is sometimes used recreationally for its hallucinogenic effects. When used recreationally, it is most commonly snorted or injected.

Fatal ketamine overdose is uncommon, but it can occur. The lethal dose of ketamine is estimated to be about 4.2 grams, or 4,200 milligrams for a 154-pound human. Taking excessive doses of ketamine, or mixing it with other drugs, can have toxic effects, including fatal respiratory depression.

Learn more about the lethal doses of commonly abused drugs.

How A Lethal Dose Of Ketamine Is Determined

While ketamine has legitimate medical uses as an anesthetic and is sometimes used recreationally, the difference between a typical dose and a potentially fatal one represents important safety information. The lethal dose of ketamine is approximately 25 times the standard recreational dose.

Standard doses of ketamine include:

• 75 to 125 milligrams (mg) when snorted
• 450 to 750 milligrams (mg) for medical anesthesia

Anyone experiencing ketamine-related medical emergencies should seek immediate professional medical attention.

What Factors Can Affect The Lethal Dose Of Ketamine?

The lethal dose of a drug can vary among individuals. Not all bodies react to drugs in the same way, and some people can be more vulnerable to ketamine’s toxic effects in smaller doses.

Risk factors for fatal overdose include:

• Injecting Ketamine: intravenous administration delivers the drug directly into the bloodstream, creating rapid onset and higher concentrations that increase overdose risk compared to other routes of administration
• Taking Ketamine With Other Drugs: combining ketamine with alcohol, opioids, benzodiazepines, or other central nervous system depressants can create dangerous effects, especially respiratory depression
• Low Drug Tolerance: people who are new to ketamine or haven’t used it recently have lower tolerance levels, making them more susceptible to overdose from doses that people with more experience with ketamine may survive
• Low Body Weight: smaller people require less of the substance to reach toxic levels, as ketamine dosage effects are closely related to body mass
• Pre-Existing Medical Conditions: heart problems, liver disease, kidney dysfunction, or respiratory conditions can impair the body’s ability to process and eliminate ketamine
• Unknown Purity or Adulterants: ketamine bought on the street may contain unknown substances or have unpredictable potency levels, making it impossible to know safe dosing amounts

According to the World Health Organization (WHO), fatal ketamine overdose is more common following the use of ketamine with other drugs, such as opiates, alcohol, or benzodiazepines. The combined use of ketamine with other drugs may overwhelm a person’s system faster and more intensely, with potentially fatal outcomes.

Recognizing The Signs Of A Ketamine Overdose

Ketamine overdose can occur after taking a very high dose of ketamine, or mixing it with other drugs. This can result in physical and psychological symptoms similar to PCP overdose.

Get matched with an affordable mental health counselor

Find a Therapist

Answer a few questions to get started

As a BetterHelp affiliate, we receive commissions if you purchase through the BetterHelp links above.

Ad

Signs of a ketamine overdose include:

• loss of consciousness
• slowed or stopped breathing
• difficulty breathing
• chest pain
• low blood pressure
• slow heart rate
• unresponsiveness
• vomiting
• seizures

Ketamine overdose can be treated if medical attention is sought. If someone has fallen unconscious, is convulsing, or has stopped breathing after taking ketamine, seek medical attention right away.

What To Do During A Ketamine Overdose

A ketamine overdose can happen quickly and without warning, particularly when the drug is taken in large amounts or combined with alcohol or other depressants. If you suspect someone is overdosing on ketamine, acting fast is critical.

Here is what to do:

• call 911 immediately and stay on the line with the dispatcher until emergency help arrives
• do not leave the person alone under any circumstances
• if the person is unconscious or unresponsive, place them on their side to prevent choking in case they vomit
• do not give the person anything to eat or drink, and do not attempt to make them vomit
• keep the environment as calm and quiet as possible, as ketamine can cause extreme confusion and agitation that may worsen in a chaotic setting
• monitor their breathing carefully and watch for signs of respiratory depression such as slow, shallow, or stopped breathing
• if the person stops breathing and you are trained in CPR, begin chest compressions while waiting for emergency services
• be prepared to tell emergency responders how much ketamine was taken, when it was taken, and whether any other substances including alcohol or opioids were involved
• if opioids may also have been taken, administer naloxone if it is available while waiting for help to arrive

Ketamine overdose is dangerous when combined with other depressants, so providing emergency responders with an account of everything that was consumed can be life-saving.

Written by the Addiction Resource Editorial Staff