When Ketamine Is Not Appropriate: Medical and Psychiatric Contraindications

Safe Care Means Knowing When to Say No

Ketamine therapy has helped many patients find relief from treatment-resistant depression, anxiety, PTSD, and chronic pain. But it isn't appropriate for everyone — and responsible prescribing means recognizing when other approaches should come first.

Psychiatric Contraindications

Active Psychosis or Schizophrenia History

Ketamine can worsen hallucinations, paranoia, and disorganized thinking. Patients with a personal history of psychosis or schizophrenia spectrum disorders should not receive ketamine.

Untreated Bipolar Disorder

Without mood stabilizers in place, ketamine may trigger manic or mixed episodes. Patients with bipolar disorder need stable psychiatric management before ketamine is considered.

Acute Suicidality With Immediate Safety Risk

While ketamine can reduce suicidal ideation, patients in immediate crisis need emergency stabilization — typically inpatient hospitalization — before outpatient ketamine therapy is appropriate.

Medical Contraindications

Severe Uncontrolled Hypertension

Ketamine temporarily elevates blood pressure. Patients with poorly controlled hypertension or recent cardiac events require medical stabilization first. Review side effects and monitoring for details.

Liver Dysfunction

Moderate-to-severe liver disease can cause ketamine to accumulate unpredictably, increasing the risk of adverse effects.

Active Substance Use Disorders

Patients with active addiction need stabilization before adding a Schedule III controlled substance to their treatment plan. Ketamine therapy is most effective when substance use is under control.

Medication Conflicts

Several medications can create unsafe interactions with ketamine:

• MAOIs — Risk of dangerous blood pressure elevation and serotonin-related complications
• High-dose benzodiazepines — Can blunt therapeutic effects
• Clozapine — Increased seizure risk
• Certain stimulants at high doses — Cardiovascular concerns

For a complete overview, see medication safety with ketamine.

Practical Requirements

Ketamine therapy requires infrastructure beyond the medication itself:

Safe Home Environment

At-home treatment requires a calm, private space free from hazards. Patients in unstable living situations may need alternative arrangements.

Peer Supervisor

A trained, sober peer supervisor must be physically present during every session. Patients who cannot arrange this are not candidates for at-home treatment.

Psychological Support

Access to a therapist or counselor — either through KAP or independent therapy — supports integration and long-term benefit.

Other Considerations

Pregnancy or Breastfeeding

Ketamine should generally be avoided during pregnancy and breastfeeding unless the clinical situation is medically urgent.

Recreational or Spiritual Intent

Patients seeking ketamine primarily for recreational experiences or without genuine therapeutic goals are not appropriate candidates for medical treatment.

Ketamine Allergy

Rare, but a definitive contraindication.

The Philosophy

Safe care means recognizing when ketamine helps — and when the priority is stabilization first. Treatment requires the right foundation: emotional support, medication stability, a safe environment, and genuine therapeutic intent. When these are in place, ketamine can be a powerful tool. Without them, other approaches should come first.