What Is Ketamine?

Ketamine (ketamine hydrochloride) is a non‑barbiturate dissociative anesthetic and analgesic. It produces profound anesthesia and analgesia by blocking N‑methyl‑D‑aspartate (NMDA) receptors and is officially approved as a general anesthetic for diagnostic and surgical procedures that do not require skeletal‑muscle relaxation, for induction of anesthesia before other agents, and as a supplement to other anesthetic agents[1]. Beyond anesthesia, low‑dose ketamine is being studied for pain management, treatment‑resistant depression, acute suicidal ideation and refractory status epilepticus, though these uses are not yet FDA‑approved[2]. Ketamine is a racemic mixture of (R)- and (S)-enantiomers; the (S)-enantiomer (esketamine) is marketed separately for certain depressive disorders[2].

Medical Uses & Indications

• General anesthesia: Ketamine is FDA‑approved to be used alone for brief diagnostic and surgical procedures that do not need muscle relaxation, to induce anesthesia before other general anesthetics, and to supplement other anesthetic agents[1].
• Off‑label applications: Clinicians use low‑dose ketamine for procedural sedation, rapid sequence intubation and acute pain management. Evidence also suggests benefits in treatment‑resistant depression, suicidal ideation and refractory status epilepticus, although these indications await FDA approval[2].

Administration & Dosing

Ketamine is supplied as a sterile injection (10–100 mg/mL). It must be administered by or under the supervision of clinicians experienced in anesthesia, with continuous monitoring of vital signs and airway management equipment available[1]. Recommended doses vary by route and goal:

• Intravenous induction: 1–4.5 mg/kg administered slowly over about 60 seconds; an average dose of 2 mg/kg typically provides 5–10 minutes of surgical anesthesia[1].
• Intramuscular induction: 6.5–13 mg/kg; 9–13 mg/kg yields about 12–25 minutes of anesthesia[1].
• Maintenance: Additional increments of half to the full induction dose may be given as needed and are often combined with other agents[1].

At doses below ~1 mg/kg IV or 3 mg/kg IM, ketamine acts primarily as an analgesic and sedative. When higher thresholds are reached, the characteristic dissociative state abruptly appears[2].

Common Adverse Effects

The most frequently reported adverse reactions include nausea, vomiting, dizziness, diplopia (double vision), drowsiness, dysphoria and confusion[2]. Emergence delirium—dream‑like imagery or hallucinations during recovery—occurs in roughly 6–12 % of patients[1]. Other organ‑system effects include transient increases in blood pressure and heart rate, muscle stiffness, nystagmus, increased salivation and injection‑site reactions[1][2]. Apnea, laryngospasm and respiratory depression can also occur, particularly with rapid administration[1].

Warnings & Precautions

• Hemodynamic effects: Ketamine stimulates the sympathetic nervous system and can markedly raise blood pressure and heart rate; it is contraindicated in patients for whom a significant blood‑pressure increase would be hazardous (e.g., aortic dissection or uncontrolled hypertension)[1][2].
• Emergence reactions: Postoperative confusion or hallucinations may occur. Reducing sensory stimulation and co‑administration of benzodiazepines can lessen these reactions[1].
• Respiratory depression: Rapid or excessive dosing may cause hypoventilation or apnea; adequate oxygenation and ventilation must be maintained[1].
• Pediatric neurotoxicity: Prolonged use (>3 hours) in children ≤3 years is associated with long‑term cognitive deficits[1].
• Hepatobiliary injury: Recurrent or chronic use has been linked to cholestatic liver injury; baseline and periodic liver‑function tests are recommended[1].
• Pregnancy, lactation & psychiatric disorders: Ketamine is not recommended during pregnancy or breastfeeding and should be avoided in patients with schizophrenia[2].
• Drug interactions & abuse potential: Ketamine is a Schedule III controlled substance. Combining it with opioids, benzodiazepines or other CNS depressants may result in profound sedation, respiratory depression or coma[1][2].

Monitoring & Care

Continuous monitoring of blood pressure, heart rate, respiration and oxygen saturation is required during and after ketamine administration[1]. Neuropsychiatric status should be assessed, and patients should remain under supervision until they return to baseline[2]. A responsible adult must accompany patients once discharged. Patients must be advised not to drive, operate heavy machinery or perform hazardous activities for at least 24 hours after ketamine administration[2].

References

1. Ketamine Injection: Package Insert / Prescribing Information. Drugs.com. Updated Sept 16 2025.
2. Ketamine. StatPearls [Internet]. National Center for Biotechnology Information. Updated Jan 30 2024.