Is Ketamine a Benzodiazepine? Why the Drug Classes Are Different

Quick answer

No, ketamine is not a benzodiazepine. They belong to entirely different drug classes, work through different receptors, and produce different effects on the body. Ketamine is an NMDA-receptor antagonist (a dissociative anesthetic with FDA-approved use for treatment-resistant depression as esketamine/Spravato). Benzodiazepines are GABA-A receptor positive allosteric modulators (sedative-hypnotic anxiolytics like Xanax, Valium, Klonopin, and Ativan). Ketamine preserves breathing, raises blood pressure, and has rapid antidepressant effects; benzodiazepines suppress breathing, lower blood pressure, and can worsen depression with long-term use. The DEA places ketamine in Schedule III and most prescription benzodiazepines in Schedule IV.

That is the short version. The longer answer matters because the confusion is common, and the clinical differences affect prescribing decisions, drug interactions, and what to expect from treatment.

Looking for the practical interaction question? If you currently take a benzodiazepine and are considering ketamine therapy, our medication safety guide walks through the specific protocol Dr. Soffer uses with patients on benzos.

The four key differences in one table

If you remember nothing else, remember this: one drug raises your blood pressure and keeps you breathing on its own. The other drug lowers your blood pressure and can suppress your breathing, especially combined with opioids. That single physiological difference is why anesthesiologists, emergency medicine physicians, and psychiatrists treat these drugs as fundamentally different tools.

What is a benzodiazepine?

Benzodiazepines are a family of sedative-hypnotic medications first introduced in 1960 (chlordiazepoxide, brand name Librium) and quickly became some of the most widely prescribed drugs in the world. The class includes:

• Alprazolam (Xanax) — short-acting, prescribed for panic disorder
• Diazepam (Valium) — long-acting, used for anxiety and muscle spasm
• Clonazepam (Klonopin) — long-acting, used for seizures and panic
• Lorazepam (Ativan) — intermediate-acting, used for anxiety and procedural sedation
• Midazolam (Versed) — very short-acting, used for procedural sedation and anesthesia induction
• Temazepam (Restoril) — intermediate-acting, used for sleep

All benzodiazepines share the same mechanism: they bind to a specific site on the GABA-A receptor and make the receptor more responsive to GABA, the brain's primary inhibitory neurotransmitter. This produces sedation, reduces anxiety, relaxes muscles, and at higher doses prevents seizures. The trade-off is that GABA-A enhancement also depresses brainstem centers that control breathing, which is why benzodiazepine overdose, particularly combined with opioids or alcohol, can cause fatal respiratory depression.

Long-term benzodiazepine use carries real risks: physical dependence develops within weeks, withdrawal can include life-threatening seizures, and several large studies have linked chronic benzodiazepine use to worsening anxiety, depression, cognitive impairment, and increased fall risk in older adults.

What is ketamine, in drug-class terms?

Ketamine was synthesized in 1962 as a safer alternative to phencyclidine (PCP) and was FDA-approved as an anesthetic in 1970. Pharmacologically, it is an NMDA-receptor antagonist: it binds inside the open NMDA receptor channel and blocks glutamate from triggering excitatory neurotransmission at that synapse. Glutamate is the brain's primary excitatory neurotransmitter, so ketamine's action is essentially the mirror image of what benzodiazepines do (which is to enhance inhibition).

That single mechanistic difference cascades into every other downstream effect:

• Because ketamine does not depress the inhibitory brainstem centers benzodiazepines target, respiratory drive is preserved at therapeutic and even anesthetic doses, which is why ketamine is widely used in emergency medicine, prehospital trauma care, and pediatric anesthesia where airway protection matters.
• Because NMDA blockade triggers a downstream surge of glutamate and a cascade of synaptic remodeling, ketamine produces rapid antidepressant effects, often within hours of a single dose, in a way no GABA-modulating drug ever has.
• Because ketamine activates sympathetic nervous system output, blood pressure and heart rate go up during the active phase, the opposite of the cardiovascular profile of benzodiazepines.

Ketamine is a DEA Schedule III controlled substance. Its S-enantiomer, esketamine, was FDA-approved as the nasal spray Spravato in 2019 for treatment-resistant depression and in 2020 for major depressive disorder with acute suicidal ideation. Off-label use of racemic sublingual ketamine for depression, anxiety, PTSD, and chronic pain has expanded rapidly over the past decade and is the model most at-home ketamine telehealth programs (including ours) follow.

Why the confusion is so common

Five reasons patients (and quite a few clinicians) lump these drugs together:

1. Both are controlled substances. Schedule III versus Schedule IV — close enough on a prescription that they look interchangeable to a non-specialist.
2. Both can produce sedation at high doses. In emergency medicine and procedural sedation, both are sometimes called "tranquilizers" by laypeople.
3. Both can affect memory. Benzodiazepines are anterograde amnestic (you cannot form new memories during peak effect), and high-dose ketamine produces dissociation that often blocks autobiographical recall of the experience. Subjectively, both can feel "blanking out."
4. They are sometimes given together in anesthesia. Midazolam (a benzodiazepine) is frequently given just before ketamine in procedural sedation, both to reduce emergence reactions and to provide pre-medication amnesia. Patients who only know they received "ketamine" may not realize they also got midazolam, and they may attribute the benzo's amnestic effect to the ketamine.
5. Both can be misused recreationally. Internet forums and drug-policy discussions often group "downers," "tranqs," and dissociatives loosely, which obscures real pharmacological differences.

The confusion is understandable; the conflation is wrong. Pharmacologically, mechanistically, and clinically, these are different drugs.

The clinical differences that actually matter

If you are a patient deciding between treatments, or a clinician comparing options, here are the five differences that change real-world decisions:

1. Respiratory safety. Ketamine is generally safe to use without continuous respiratory monitoring at sublingual antidepressant doses. Benzodiazepines, particularly when combined with opioids or alcohol, carry overdose risk that requires monitoring. The FDA black-box warning on benzodiazepine-opioid combinations exists because the combination kills people; there is no equivalent warning on ketamine-opioid use (though caution is still warranted in opioid-dependent patients).

2. Cardiovascular profile. A patient with uncontrolled hypertension or unstable cardiovascular disease usually cannot safely take ketamine (the sympathetic surge stresses the system). The same patient may tolerate benzodiazepines fine. The reverse is also true: a patient with severe sleep apnea who is not on CPAP is a high-risk benzo candidate but a much lower-risk ketamine candidate.

3. Effect on depression itself. This is the one most patients don't know about. The published evidence on benzodiazepines and depression points in a concerning direction. Long-term benzodiazepine use is associated with worsened depression outcomes in observational data, and several reviews have argued benzodiazepines should not be first-line for depression-comorbid anxiety because of this. Ketamine, by contrast, is one of the few psychiatric medications with rapid antidepressant effects, often within 4 to 24 hours of a single dose.

4. Addiction and withdrawal. Both drugs have abuse potential, but the profiles are different. Benzodiazepine dependence develops with chronic use and carries one of the most dangerous withdrawal syndromes in medicine (potential for seizures, delirium, autonomic instability). Ketamine has psychological dependence risk and, at chronic recreational doses, bladder toxicity, but does not produce the seizure-prone physical withdrawal of benzodiazepines. Our full risks and side effects guide covers the ketamine-specific monitoring points in detail.

5. Mechanism of action and what they treat. Benzodiazepines are first-line for acute alcohol withdrawal, status epilepticus, and procedural anxiety. Ketamine is first-line for nothing in psychiatry yet (in psychiatry the FDA-approved indication is via Spravato), but it is a major option for treatment-resistant depression, suicidal ideation in MDD, and emerging research areas including PTSD and chronic pain. They are not interchangeable for any indication. For anxiety specifically, our ketamine as a benzodiazepine alternative post covers when ketamine is and is not a reasonable substitute for chronic benzodiazepine use.

What this means if you currently take a benzodiazepine

Two practical points if you are on a benzo and considering ketamine therapy:

Concurrent benzodiazepine use can blunt ketamine's antidepressant effect. The published evidence here is suggestive rather than airtight, but the signal is consistent across multiple observational and post hoc analyses: patients on chronic benzodiazepines often show smaller and shorter-lasting responses to ketamine for depression than benzodiazepine-naive patients. The proposed mechanism is that GABA-A enhancement (from the benzo) dampens the glutamate surge that follows NMDA blockade (the ketamine antidepressant signal). It does not mean ketamine cannot work alongside a benzo; it means we typically aim to either taper the benzo first, time benzo doses away from session days, or set expectations that response may be more gradual.

Do not abruptly stop your benzodiazepine to start ketamine. Benzodiazepine withdrawal is dangerous and can be life-threatening. If a taper makes clinical sense, it is done slowly over weeks to months under physician supervision, often before ketamine begins. Patients should never make this change on their own.

In our medication safety guide, we walk through the specific approach Dr. Soffer uses, which patient profiles benefit from a pre-ketamine benzodiazepine taper, and which patients are usually fine continuing their benzo as-is. The SSRIs and ketamine guide covers the parallel question for antidepressants.

Want to know whether ketamine therapy is right for you?

At Discreet Ketamine, every patient is reviewed personally by Dr. Ben Soffer, a board-certified physician, before any prescription is issued. We serve patients in Florida and New Jersey, with medication delivered directly to your home from a licensed U.S. compounding pharmacy.

If you currently take a benzodiazepine and want to know whether ketamine is a reasonable next step for treatment-resistant depression, anxiety, PTSD, or chronic pain, the five-minute eligibility check is the place to start. If the answer is no, we will refer you somewhere it is yes.

Check your eligibility →

References

1. Sanacora G, et al. A Consensus Statement on the Use of Ketamine in the Treatment of Mood Disorders. JAMA Psychiatry. 2017;74(4):399-405. PMID 28249076. The American Psychiatric Association consensus on ketamine pharmacology, mechanism, and clinical use.

2. Krystal JH, et al. Ketamine: A Paradigm Shift for Depression Research and Treatment. Neuron. 2019;101(5):774-778. PMID 30844397. Reviews the NMDA-antagonist mechanism and the downstream glutamate surge that produces rapid antidepressant effects.

3. U.S. Drug Enforcement Administration. Controlled Substances - Alphabetical Order. Lists ketamine as Schedule III; most clinically used benzodiazepines (alprazolam, clonazepam, diazepam, lorazepam) as Schedule IV. Available at deadiversion.usdoj.gov.

4. U.S. Food and Drug Administration. Spravato (esketamine) Prescribing Information. FDA approval for treatment-resistant depression (2019) and major depressive disorder with acute suicidal ideation (2020). FDA label.

5. Feeney A, Hoeppner BB, Freeman MP, et al. Effect of Concomitant Benzodiazepines on the Antidepressant Effects of Ketamine: Findings From the RAPID Intravenous Ketamine Study. J Clin Psychiatry. 2022 Nov;83(6):21m14491. PMID 36383742. Recent RAPID study finding that concomitant benzodiazepine use is associated with reduced ketamine antidepressant response in treatment-resistant depression.

6. Andrashko V, Novak T, Brunovsky M, et al. The Antidepressant Effect of Ketamine Is Dampened by Concomitant Benzodiazepine Medication. Front Psychiatry. 2020;11:844. PMID 33005153. Independent observational confirmation of the benzodiazepine-blunting effect on ketamine's antidepressant response.

Frequently Asked Questions

Is ketamine a benzodiazepine?

No. Ketamine is an NMDA-receptor antagonist (a dissociative anesthetic). Benzodiazepines are GABA-A receptor positive allosteric modulators (sedative-hypnotic anxiolytics). They belong to entirely different drug classes, work through different receptors, and produce different effects on breathing, blood pressure, and depression outcomes. Ketamine is DEA Schedule III; most clinically used benzodiazepines are Schedule IV.

Is ketamine a benzo or a barbiturate?

Ketamine is neither. Barbiturates (phenobarbital, secobarbital) also work via the GABA-A receptor but at a different binding site than benzodiazepines, and produce similar sedation and respiratory depression. Ketamine works on the NMDA receptor (a glutamate receptor, not GABA), so its mechanism, effects on breathing, and effects on blood pressure all differ from both benzodiazepines and barbiturates.

What drug class is ketamine in?

Ketamine is classified as a dissociative anesthetic and, mechanistically, as an NMDA-receptor antagonist. It is also sometimes grouped with other glutamate-modulating psychiatric medications. The DEA classifies it as a Schedule III controlled substance. It is not a sedative-hypnotic, not a benzodiazepine, not a barbiturate, and not an opioid.

Can you take ketamine and benzodiazepines together?

Concurrent use is possible but requires careful clinical management. Two cautions: (1) benzodiazepines can dampen ketamine's antidepressant response, so response may be smaller or shorter-lasting; (2) combined CNS depressant effects can occur at higher doses, particularly with respiratory monitoring concerns if both are dosed close together. Many ketamine programs ask patients to time their benzodiazepine doses away from session days, or to taper before starting if clinically appropriate. Never stop a benzodiazepine abruptly on your own.

Why do people think ketamine is a benzo?

Five common reasons: both are controlled substances, both can cause sedation at higher doses, both affect memory at certain doses (benzos cause amnesia, high-dose ketamine causes dissociative memory blunting), midazolam (a benzodiazepine) is sometimes given alongside ketamine in anesthesia, and recreational drug discussion forums often lump CNS depressants together regardless of their actual pharmacology. The conflation is widespread but pharmacologically incorrect.

Is ketamine safer than benzodiazepines?

In some ways yes, in some ways no. Ketamine preserves respiratory drive at therapeutic doses; benzodiazepines suppress it (especially combined with opioids or alcohol). Ketamine does not produce the seizure-prone withdrawal syndrome of benzodiazepines. On the other hand, ketamine raises blood pressure and heart rate, so it is contraindicated in uncontrolled hypertension and unstable cardiovascular disease where benzodiazepines may be safer. And chronic recreational ketamine use carries bladder toxicity that benzodiazepines do not. "Safer" depends on the patient and the indication.

Does ketamine cause physical dependence like a benzo?

No, not in the same way. Chronic benzodiazepine use produces physical dependence within weeks, and abrupt cessation can cause seizures, autonomic instability, and delirium, sometimes fatal. Ketamine has psychological dependence risk and, at chronic recreational doses, can cause bladder toxicity (ketamine-induced cystitis), but does not produce the seizure-prone physical withdrawal syndrome that defines benzodiazepine dependence. Therapeutic doses prescribed under medical supervision carry very different risk profile from chronic recreational use.

Is Spravato a benzodiazepine?

No. Spravato is the brand name for esketamine, the S-enantiomer of ketamine, delivered as a nasal spray. It is the FDA-approved formulation of ketamine for treatment-resistant depression (2019) and major depressive disorder with acute suicidal ideation (2020). Like racemic ketamine, esketamine is an NMDA-receptor antagonist, not a benzodiazepine.