Who Should Avoid Ketamine?
Just as important as understanding who might be a good candidate for ketamine therapy is understanding who should generally avoid it, or approach it only with significant additional caution. This article covers the major categories of contraindications and risk factors that reputable providers screen for, based on ketamine’s known pharmacology and the current clinical research literature.
Uncontrolled Cardiovascular Conditions
Because ketamine commonly causes transient increases in blood pressure and heart rate, patients with poorly controlled hypertension, significant cardiovascular disease, a history of aneurysm, or certain other cardiac conditions are generally considered poor candidates for treatment, or require careful cardiology input and closer monitoring if treatment is considered at all. This is one of the most consistently emphasized screening criteria across ketamine and esketamine treatment protocols, and it reflects a straightforward pharmacological concern rather than a more uncertain or debated risk factor.
History of Psychosis or Certain Psychotic Disorders
Patients with a personal history of schizophrenia, schizoaffective disorder, or other psychotic disorders are generally advised against ketamine treatment. This caution stems from ketamine’s mechanism as an NMDA receptor antagonist, which has been studied, including in controlled research settings, for its ability to transiently reproduce certain features of psychotic symptoms in healthy volunteers — reflecting a genuine, mechanistically grounded concern rather than a purely precautionary one. Esketamine’s FDA labeling specifically lists a personal or family history of psychosis as an important consideration in the prescribing decision.
Uncontrolled Substance Use Disorders
Given ketamine’s own recognized potential for misuse and psychological dependence, patients with an active, uncontrolled substance use disorder are generally not considered good candidates for treatment, or would need this issue addressed as a priority before ketamine treatment could be responsibly considered. This isn’t a blanket exclusion for anyone with any history of substance use, but it does reflect the importance of a thorough, honest substance use history as part of the evaluation process, and ongoing attention to this risk throughout treatment.
Pregnancy and Breastfeeding
Ketamine’s safety during pregnancy and breastfeeding has not been well established through rigorous clinical research, and it is generally not recommended for depression or pain treatment during pregnancy outside of specific medical circumstances where an anesthesiologist or other specialist has made a careful risk-benefit determination for an unrelated medical need. Esketamine’s FDA labeling specifically advises against its use during pregnancy based on animal studies suggesting potential risk to the fetus, and patients who are pregnant or breastfeeding should have a detailed conversation with their provider about these specific risks rather than assuming general safety information about ketamine applies to their situation.
Certain Respiratory Conditions
Given ketamine’s potential, particularly at higher doses, to affect respiratory drive, patients with significant underlying respiratory conditions may require additional caution or closer monitoring, and this should be part of a thorough medical history review before treatment.
Elevated Intracranial or Intraocular Pressure
Historically, there was significant concern about ketamine’s use in patients with elevated intracranial pressure (pressure within the skull, relevant in certain neurological conditions and head injuries) or elevated intraocular pressure (relevant in certain eye conditions like glaucoma), based on older research suggesting ketamine might increase these pressures. More recent research has somewhat softened this concern in certain contexts, but it remains a factor that should be specifically discussed with a provider by patients with a history of these conditions, since practice in this area has evolved and nuance matters.
Certain Liver Conditions
Because ketamine is metabolized by the liver, patients with significant liver impairment may require dose adjustments or additional caution, and this should be part of a thorough medical history discussion, particularly for patients receiving oral or sublingual ketamine, given the more significant liver metabolism (first-pass effect) involved in that administration route, discussed in more detail in the article on comparing administration routes.
Known Hypersensitivity to Ketamine
As with any medication, a known allergy or hypersensitivity reaction to ketamine itself is a straightforward contraindication.
Bipolar Disorder: A More Nuanced Consideration
Patients with bipolar disorder, particularly bipolar I disorder with a history of mania, are generally approached with additional caution regarding ketamine treatment, given theoretical concerns that NMDA receptor antagonists could potentially trigger manic or hypomanic symptoms in susceptible individuals. This isn’t necessarily an absolute contraindication in every case, but it’s an important factor that should be discussed thoroughly with a psychiatric provider experienced in treating bipolar disorder specifically, since this requires more nuanced clinical judgment than some of the more clear-cut contraindications discussed elsewhere in this article.
Certain Medication Interactions
Patients taking other central nervous system depressants — including benzodiazepines, opioids, or certain other sedating medications — may face an increased risk of excessive sedation or respiratory depression when combined with ketamine, which is why a complete medication list is an essential part of pre-treatment screening, and why some medication adjustments might be recommended before starting treatment, always under the guidance of the prescribing physicians involved.
Age-Related Considerations
As noted in the companion article on candidacy, esketamine’s FDA approval is specific to adults, and the use of ketamine for psychiatric indications in children and adolescents remains a considerably less studied area, generally approached with additional caution and typically only within specialized pediatric psychiatric research or clinical settings, rather than standard adult ketamine treatment protocols.
Why These Screening Criteria Matter
It’s worth emphasizing that these contraindications and risk factors exist precisely because ketamine is a pharmacologically active medication with real physiological effects, not an inert or universally benign substance. A thorough screening process that takes these factors seriously — rather than a cursory intake form — is one of the clearest signs of a responsible, well-run ketamine or esketamine treatment program, discussed further in a dedicated article later in this series on choosing a qualified clinic.
What Patients Should Disclose During Screening
Given how central accurate screening is to safe treatment, patients considering ketamine therapy should be prepared to discuss openly and honestly:
– Their complete psychiatric history, including any history of psychosis or bipolar disorder.
– Their complete cardiovascular history, including blood pressure control.
– Any history of substance use, past or present.
– All current medications and supplements.
– Pregnancy status or plans, if relevant.
– Any history of liver, kidney, or respiratory conditions.
– Any prior reactions to ketamine or related medications.
Withholding this information, even out of embarrassment or a desire to be approved for treatment, undermines the safety of the entire process and should be avoided.
The Bottom Line
Ketamine is not appropriate for everyone, and legitimate contraindications and risk factors — including uncontrolled cardiovascular disease, a history of psychosis, active substance use disorders, pregnancy, and certain other medical conditions — exist for well-understood pharmacological reasons. A thorough, honest evaluation of these factors, conducted by a qualified provider and supported by complete, honest disclosure from the patient, is essential to using ketamine safely and appropriately.
*This article is for educational purposes only and does not constitute medical advice. Only a licensed healthcare provider can determine whether ketamine or esketamine treatment is appropriate or contraindicated for a specific individual.*