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Ketamine Facts

Dissociative; Arylcyclohexylamine; NMDA receptor antagonist

Description

Ketamine — special K, ket, vitamin K — is a synthetic dissociative of the arylcyclohexylamine class. It blocks glutamate signaling in the brain,[1] producing a progressive disconnection from sensory reality.

Subjective effects include depersonalization, derealization, bodily dissociation, time alteration, and analgesia. The experience is one of progressive disconnection — sensory input arrives but fails to cohere, producing a floating detachment that deepens toward complete severance from external reality at higher doses.

Psychological dependence is high — short duration encourages compulsive redosing, and ketamine activates dopamine reward circuits;[2][3] sole-agent fatality is rare.[4] Chronic use causes devastating bladder damage, liver injury, and cognitive decline;[5][6] combining with opioids or depressants is the primary cause of death.[7]

Dose and durationby route · individual sensitivity varies

Oral(mg)
Threshold< 50 mgLight50 – 100 mgCommon100 – 200 mgStrong200 – 300 mgHeavy300+ mg

Starts in 15 – 30 minLasts 2 – 4 hoursAfter-effects 2 – 8 hours

Body and dependence

Acute toxicity
Low
Chronic toxicity
High
Physical dependence
Moderate
Psychological dependence
High
Withdrawal
Moderate
Compulsive redosing
High

Tolerance

Builds
Moderate
Fully resets after
4 weeks
Carries over to
phencyclidine; methoxetamine; deschloroketamine; 2-fluorodeschloroketamine; nitrous oxide

Effectslikely at a common dose

Perception
Touch suppression; Spatial disorientation; Depth perception distortion; +18 possible, including Vestibular distortion, Visual acuity suppression, Visual haze / noise
Body
Pain suppression; Motor control impairment; +27 possible, including Nystagmus (eye wobbles), Dizziness, Vasoconstriction
Thinking
Focus suppression; Cognitive impairment; Thought disorganization; Memory suppression; +21 possible, including Confusion, Analysis suppression, Decision impairment
Feeling
none likely · 7 possible, including Empathy suppression, Anxiety, Emotional lability
Self
Depersonalization; Derealization; +5 possible, including Communication suppression, Social disconnection, Craving
Time
Time alteration; +3 possible, including Temporal disorientation
Awareness
none likely · 2 possible

Who shouldn't take it

Absolute
Uncontrolled hypertension; Severe cardiovascular disease; Concurrent opioid or CNS depressant use; Psychotic disorders; Pregnancy
Relative
Hepatic impairment; Pre-existing urinary tract disease; Thyrotoxicosis

Combinations79 recorded

Lethal (23)
Acetylfentanyl; Benzodiazepines, Barbiturates; Buprenorphine; Codeine; Dihydrocodeine; Ethylmorphine; Fentanyl; GHB, Baclofen; GHB, GBL; Heroin; Hydrocodone; Hydromorphone; Kratom; Local anesthetics; Methadone; Morphine; O-Desmethyltramadol; Oxycodone; Oxymorphone; Sufentanil; Tapentadol; Tramadol; U-47700
Dangerous (35)
Alpha-2 adrenergic receptor antagonist; Amphetamines; Benzodiazepines; Buprenorphine, Kratom; Cannabis, THC; Clonidine, Guanfacine; Gabapentin, Pregabalin; MDMA, Amphetamines; Naltrexone; NRIs; NSAIDs; Stimulants; THC; Anticholinergics; Antihistamines; Atypical antipsychotics; Buspirone; Caffeine; CBD; Dopamine agonists; DXM; Glutamate modulator; Huperzine A; Ibogaine; and 11 more, see full page
Caution (17)
See full page: psychedex.org/substances/ketamine
Not graded (4)
Not listed never means safe.

Seek help immediately if

  • Severe disorientation; unable to move or speak (deep dissociation / "k-hole")
  • Complete loss of coordination — cannot stand or walk safely
  • Vomiting while incapacitated (choking / aspiration risk)
  • Very high blood pressure; fast heart rate
  • Slow or shallow breathing at high doses (especially mixed with depressants)
  • Unconsciousness; rarely, seizures

What to do

  1. Move them somewhere safe, away from stairs, water, roads, and sharp edges — they cannot protect themselves
  2. Place in the recovery position if vomiting or unconscious (aspiration is a key risk)
  3. Stay with them and reassure calmly; keep the environment quiet
  4. If breathing is slow/shallow or they are unresponsive, call emergency services
  5. Do not let them wander; do not leave them alone
  6. Be ready to give rescue breaths / CPR

Effects wear off with time in a safe, monitored setting. The main dangers are physical injury and aspiration while incapacitated, and respiratory depression when combined with other depressants — not the dissociation itself.

988 Suicide & Crisis LifelineFireside Project: 62-FIRESIDE

Version r1 · Not medical advice

References

  1. [1]
    ^Mion G, Villevieille T (2013) Ketamine Pharmacology: An Update (Pharmacodynamics and Molecular Aspects, Recent Findings) — CNS Neuroscience & Therapeutics doi:10.1111/cns.12099
  2. [2]
    ^Seeman P, Ko F, Tallerico T (2005) Dopamine receptor contribution to the action of PCP, LSD and ketamine psychotomimetics — Molecular Psychiatry PMID:15852061
  3. [3]
    ^Cosci F, Chouinard G (2020) Acute and Persistent Withdrawal Syndromes Following Discontinuation of Psychotropic Medications — Psychotherapy and Psychosomatics doi:10.1159/000506868
  4. [4]
    ^Schep LJ, Slaughter RJ, Watts M, Mackenzie E, Gee P (2023) The clinical toxicology of ketamine — Clinical Toxicology doi:10.1080/15563650.2023.2212125
  5. [5]
    ^Castellani D, Pirola GM, Gubbiotti M, Rubilotta E, Gudaru K, Gregori A, Dellabella M (2020) What urologists need to know about ketamine-induced uropathy: A systematic review — Neurourology and Urodynamics doi:10.1002/nau.24341
  6. [6]
    ^Sun L, Li Q, Li Q, Zhang Y, Liu D, Jiang H, Pan F, Yew DT (2014) Chronic ketamine exposure induces permanent impairment of brain functions in adolescent cynomolgus monkeys — Addiction Biology doi:10.1111/adb.12004
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