What are the contraindications for ketamine?

Ketamine Contraindications

Ketamine is contraindicated in patients for whom a significant elevation of blood pressure would constitute a serious hazard, and in patients with known hypersensitivity to ketamine or its excipients. 1

Absolute Contraindications

Cardiovascular Conditions

• Patients at risk from blood pressure elevation including those with:
  • Ischemic heart disease 2
  • Cerebrovascular disease 2
  • Uncontrolled hypertension 2
  • Severe cardiac disease 2

The FDA explicitly states this as a formal contraindication because ketamine produces dose-dependent increases in heart rate, blood pressure, and cardiac output through sympathetic nervous system stimulation. 1, 2 Blood pressure increases of 10-50% above baseline are typical, peaking at 30-50 minutes post-administration. 3

Hypersensitivity

• Known hypersensitivity to ketamine or any excipient 1

Relative Contraindications and High-Risk Situations

Neurological Conditions

• High intracranial pressure - Though historically considered an absolute contraindication, this has been refuted by recent evidence. 4, 2

  • Meta-analysis shows ketamine does not increase ICP compared to opioids (mean difference 1.94 mmHg, 95% CI -2.35 to 6.23, P=0.38) 5
  • Ketamine actually decreased ICP by 30% in pediatric patients with intracranial hypertension 6
  • However, the FDA still lists high intracranial pressure as a contraindication 2, so exercise caution and ensure adequate ventilation and sedation

• High ocular pressure 2

Psychiatric Conditions

• Active psychosis 4, 2
  • Emergence reactions occur in 10-30% of adults, manifesting as hallucinations, vivid dreams, floating sensations, and delirium 2, 1
  • These can be minimized with co-administration of benzodiazepines 2, 1

Hepatic Dysfunction

• Severe liver dysfunction 4
  • Ketamine undergoes extensive hepatic metabolism via CYP2B6, CYP3A4, and CYP2C9 7

Obstetric Considerations

• Pregnancy 4
  • All ketamine formulations are contraindicated in women who are or may become pregnant 4

Critical Clinical Pitfalls

Blood Pressure Management

• Always assess blood pressure prior to ketamine administration 3
• Hypertensive patients require effective lifestyle or pharmacologic management before treatment 3
• Monitor blood pressure continuously after dosing until values return to acceptable levels 3
• If blood pressure remains elevated, provide acute management 3
• Hypertensive crisis requires immediate emergency care 3

Airway Procedures

• Avoid ketamine as a sole anesthetic agent for procedures of the pharynx, larynx, or bronchial tree 1
  • Ketamine does not suppress pharyngeal and laryngeal reflexes 1
  • Muscle relaxants may be required for successful completion 1
  • Ketamine increases upper airway secretions 8

Drug Interactions

• Contraindicated with monoamine oxidase inhibitors (though this is listed for phentermine combinations in obesity management context) 4
• Avoid combination with other CNS depressants due to risk of serious respiratory depression 8

Special Populations

• Patients with sepsis or critical illness may have blunted or reversed hemodynamic responses to ketamine 2
• Post-cardiac arrest patients - sympathomimetic effects may be disadvantageous 2