How Many Ketamine Treatments for Depression?

Most adults with treatment-resistant depression complete an induction series of around six off-label IV ketamine sessions over two to three weeks. What comes after that, and whether you need more or fewer sessions, depends on your diagnosis, how you respond, and which form of ketamine you are using. This article explains what the evidence supports.

Medically reviewed by Jacque Lovely, RN, MN, MBA, PMP, Reg #74334 on 2026-05-27.

Key takeaways

• Induction series: most Canadian programs use 4–8 off-label IV ketamine sessions over 2–3 weeks, typically twice weekly. Six sessions is the most common course.
• Spravato (esketamine) is different: Health Canada's approved induction is twice-weekly for four weeks (8 sessions), then weekly through weeks 5–8 — 12 sessions over 8 weeks total.
• Maintenance is individualized: some adults stay in remission with no further dosing; others need monthly or quarterly boosters.
• SUSTAIN-1 evidence: continued Spravato dosing significantly extended time to relapse compared to stopping (Daly 2019 [PMID 31166571]).
• Durability evidence: a large retrospective effectiveness study reported large effects at 3 months (d = 0.75–0.86), sustained more modestly at 6 months (d = 0.61–0.73), though follow-up attrition was high (Yermus 2024).
• Predictors of needing more sessions: chronicity of treatment-resistant depression, comorbid anxiety or PTSD, and concurrent benzodiazepines above 8 mg diazepam-equivalent daily (Andrashko 2020).
• At ATMA CENA: your treatment plan is revisited at each session, so the course can be extended, tapered, or adjusted based on how you respond.

If you want to understand how a course might be structured for your specific situation, book a free information call with ATMA CENA's clinical team.

What is the standard induction series?

For adults with treatment-resistant depression, most Canadian programs and CANMAT 2021 guidance support an induction series of 4 to 8 off-label IV ketamine sessions delivered over 2 to 3 weeks, typically twice weekly. Six sessions across three weeks is the most common structure in Canadian clinical practice.

CANMAT 2021 (Swainson et al., Canadian Journal of Psychiatry — PubMed 33174760) places IV racemic ketamine as a third-line treatment for adults with treatment-resistant depression at the standard 0.5 mg/kg over 40 minutes protocol. Twice-weekly scheduling is supported by Singh et al. 2016 (Am J Psychiatry — PubMed 27056608), which found twice-weekly and thrice-weekly IV ketamine comparable in efficacy in treatment-resistant depression, with twice-weekly showing somewhat better tolerability.

A Canadian study at the Royal Ottawa (Phillips et al. 2019, Am J Psychiatry — PubMed 30764648) found roughly 28% response after a single dose rising to approximately 60% response across a six-dose course, supporting the value of completing a full series rather than stopping after one or two sessions.

The safety of this course is supported by a pooled analysis of 205 IV ketamine infusions in 97 adults with treatment-resistant depression across three trials (Wan/Murrough 2015, J Clin Psychiatry — PubMed 25271445): 67% response rate, 1.95% infusion discontinuation rate, no persistent psychotomimetic effects, no increased substance use.

Important framing: off-label IV ketamine use for depression is regulated by provincial colleges of physicians and surgeons (e.g., CPSA in Alberta, CPSO in Ontario) under their respective ketamine guidance frameworks. See the compliance block at the end of this article.

How does Spravato's course differ?

Spravato (intranasal esketamine) is Health Canada-approved for treatment-resistant MDD and follows a different, longer induction protocol than off-label IV ketamine.

Health Canada-approved Spravato induction:

Phase	Schedule	Sessions
Weeks 1–4	Twice-weekly (56 mg or 84 mg per session) + concurrent oral SSRI or SNRI	8 sessions
Weeks 5–8	Weekly	4 sessions
Maintenance	Weekly or every-other-week, individualized	Ongoing

Total induction: 12 sessions over 8 weeks. Each Spravato session also requires at least two hours of mandatory in-clinic observation under the Janssen Journey program, making total in-clinic time substantially greater per session than IV ketamine (approximately 150–180 minutes versus 90–120 minutes).

The key distinction: Spravato is Health Canada-approved for treatment-resistant MDD only. The separate US FDA MDSI indication (MDD with acute suicidal ideation) has not been confirmed as a Health Canada-approved indication as of 2026-05-27. Off-label IV ketamine and Spravato are distinct products with different regulatory pathways, schedules, and insurance coverage profiles.

What does the maintenance evidence say?

Antidepressant effects from an induction series typically peak within 24 hours and, without maintenance dosing, often begin to wane over one to four weeks. Two randomized studies anchor what we know about maintenance.

SUSTAIN-1 (Daly et al. 2019, JAMA Psychiatry — PubMed 31166571) randomized 297 stable remitters and responders on Spravato plus an oral antidepressant to either continue treatment or switch to placebo plus oral antidepressant. Those who continued Spravato experienced significantly longer time to relapse. In the remission subgroup, relapse occurred in 26.7% of the continued-Spravato group versus 45.3% in the stopped group (p = 0.003; NNT = 6). The study establishes that continued dosing extends remission rather than producing a lasting one-shot effect.

SUSTAIN-2 (Wajs et al. 2020, J Clin Psychiatry — PubMed 32316080) followed 802 adults on Spravato plus an oral antidepressant for up to one year. It is the largest published long-term dataset for any ketamine product. The study found no cases of interstitial cystitis, stable or improved cognitive function, and adverse events that were mostly mild-to-moderate and resolved the same day.

Real-world durability: Yermus et al. 2024 (Psychedelic Med — PubMed 40051583) retrospectively analyzed adults who received ketamine-assisted psychotherapy at Field Trip Health clinics across North America (March 2020–June 2022). Among those with follow-up data, Cohen's d effect sizes on depression measures were 0.75–0.86 at three months and 0.61–0.73 at six months — large, sustained effects, though the authors note substantial follow-up attrition that limits how firmly the results generalize.

For IV ketamine maintenance in Canadian practice, the typical tapering sequence is: twice-weekly acute induction, then weekly, then every two weeks, then monthly — slowing as durability allows.

What factors influence how many sessions someone needs?

The right course is calibrated to the individual. Several variables associate with response trajectory, though predicting individual outcomes remains imperfect:

• Chronicity of treatment-resistant depression. Longer illness duration and more prior antidepressant failures often favour extending the acute series (toward 8 sessions rather than 4–6) and transitioning earlier to maintenance.
• Comorbid PTSD, anxiety, or chronic pain. Each adds to the symptomatic landscape. Comorbid conditions may respond over time but often warrant additional sessions or a longer integration phase.
• Concurrent benzodiazepines. Andrashko et al. 2020 (Front Psychiatry — PubMed 33005153) found that concomitant benzodiazepines above 8 mg diazepam-equivalent daily significantly attenuated IV ketamine's antidepressant effect (p = 0.007 for non-responders vs. responders). Your clinical team will discuss timing or tapering with your prescriber where appropriate.
• Family history of alcohol use disorder. Reproducibly associated with better ketamine response in multiple analyses.
• Suicidal ideation as a primary symptom. Ketamine produces rapid reductions in suicidal ideation; this subgroup may stabilize quickly but often benefits from maintenance to prevent relapse.
• Partial response after initial sessions. Common. Options include extending the acute series, adding or intensifying integration psychotherapy, or addressing contributing comorbidities.

What happens if you don't respond?

No response after 4–6 acute infusions warrants re-evaluation by the clinical team. Common reasons include:

• Undiagnosed bipolarity (mood history rescreen)
• Pseudoresistance — inadequate prior antidepressant trials
• Medication interactions (concurrent benzodiazepines above the 8 mg threshold)
• Genuine ketamine non-response in a small proportion of adults

Options at this point include switching route or molecule (for example, IV to Spravato, or adding integration psychotherapy), adjusting dosing, or considering an alternative. The ELEKT-D trial (Anand et al. 2023, N Engl J Med — PubMed 37224232) found IV ketamine non-inferior to electroconvulsive therapy (ECT) for non-psychotic treatment-resistant depression in 403 adults (response: 55.4% ketamine vs. 41.2% ECT), establishing ECT as a comparator — not a replacement — for ketamine non-responders.

Induction and maintenance at a glance

	Off-label IV ketamine	Spravato (esketamine)
Sessions in acute course	4–8 over 2–3 weeks	12 over 8 weeks
Typical schedule	Twice-weekly	Twice-weekly (wks 1–4), weekly (wks 5–8)
In-clinic time per session	~90–120 min	~150–180 min (incl. 2-hr observation)
Health Canada status	Off-label (anaesthetic approval only)	Approved for treatment-resistant MDD
Insurance coverage	Generally not covered (off-label)	Most likely to qualify for private prior-auth
Maintenance structure	Individualized; typically taper from weekly to monthly	Weekly or every-other-week, individualized

ATMA CENA program and session counts

ATMA CENA's ketamine-assisted therapy (KAT) program bundles clinical assessment and prescription, preparation, the medicine session, and integration into one course, delivered by intranasal, intramuscular, or oral ketamine (ATMA CENA does not offer IV). Treatment is offered in two forms at the same price — a psychedelic approach (a low dose for introspection) and a psycholytic approach (a lower dose during therapy):

	Price
Initial treatment	$1,590
Each additional medicine session	$800
Multi-session packages (2–8 treatments)	$2,390–$6,500 (discounted)

A $300 non-refundable deposit applies to your treatment. For full pricing context, see Ketamine Therapy Cost in Canada.

ATMA CENA's clinical team revisits the treatment plan at each session and can extend, taper, or adjust the course based on your response trajectory. If you want to discuss how a course might look for your situation, book a free information call.

Frequently asked questions

How many ketamine sessions does it take to treat depression?

For off-label IV ketamine in treatment-resistant depression, most Canadian programs use 4 to 8 sessions over 2 to 3 weeks — six sessions across three weeks is the most common structure. For Spravato, the Health Canada-approved induction is 12 sessions over 8 weeks. Individual response, comorbidities, and which ketamine product you are using all affect the total number of sessions.

Do I need ongoing maintenance sessions?

Often yes, but not always. SUSTAIN-1 demonstrated that continued Spravato dosing significantly extended time to relapse versus stopping. SUSTAIN-2 confirmed acceptable safety over one year. Some adults sustain remission after an acute course with no further dosing; others benefit from monthly or quarterly boosters. Maintenance planning is part of intake and is revisited as your response unfolds.

How quickly does ketamine work for depression?

Antidepressant effects are often observed within 24 hours of a dose — substantially faster than traditional antidepressants. Across a 4–6 session acute course, response rates climb. Trajectories vary: some adults respond strongly after the first or second session; others develop response across the series.

What if I don't respond after the first few sessions?

Re-evaluate with the clinical team. Common reasons for non-response include undiagnosed bipolarity, medication interactions (especially benzodiazepines above 8 mg diazepam-equivalent daily), or genuine non-response in a minority of adults. Options include adjusting dosing, switching route or molecule, or considering alternatives such as ECT, which was shown non-inferior to IV ketamine in the ELEKT-D trial (Anand 2023).

Will I need ketamine treatments forever?

Not necessarily. Some adults complete one acute course and remain in remission with appropriate psychotherapy and aftercare. Others maintain occasional boosters — monthly, quarterly, or at first sign of relapse. A smaller group benefits from ongoing maintenance indefinitely. The framing that fits: ketamine is a treatment, not a cure, and durability planning is built into ATMA CENA's intake process.

Is Spravato more sessions than IV ketamine?

Yes. The Health Canada Spravato induction is 12 sessions over 8 weeks, compared to 4–8 sessions over 2–3 weeks for off-label IV ketamine. Spravato sessions also require mandatory two-hour in-clinic observation, so total in-clinic time per session is greater.

Can I do a shorter course if I respond quickly?

Possible, but it is a clinical decision. Some adults with rapid, robust response transition earlier to maintenance; others benefit from completing the planned series for durability. ATMA CENA's team revisits the plan at each session.

What is the difference between IV ketamine and Spravato?

IV ketamine (racemic ketamine) is off-label for psychiatric use in Canada — it is Health Canada-approved as an anaesthetic only. Spravato (intranasal esketamine) is Health Canada-approved for treatment-resistant MDD in adults. They differ in molecule, route, schedule, regulatory status, and insurance coverage.

Compliance disclaimer

Ketamine off-label use — Canadian regulatory framing

Racemic ketamine holds a Health Canada approval as a general anaesthetic. All psychiatric applications — including IV and intramuscular administration for treatment-resistant depression and other mental-health indications — are off-label uses regulated by provincial colleges of physicians and surgeons. In Alberta, off-label IV ketamine requires NSHF (Non-Surgical/Hospital Facility) accreditation under CPSA guidance. In Ontario, IV ketamine is subject to OHPIP (Out-of-Hospital Premises Inspection Program) standards. In Manitoba, IV ketamine must be administered in CPSM-accredited non-hospital medical or surgical facilities. Provincial frameworks vary; ATMA CENA's clinical team will explain what applies to your location.

Spravato (intranasal esketamine) is Health Canada-approved for treatment-resistant MDD in adults who have not responded adequately to at least two courses of different antidepressants, in combination with an oral SSRI or SNRI. A separate MDSI indication (MDD with acute suicidal ideation) exists under US FDA labelling but has not been confirmed as an approved Health Canada indication as of 2026-05-27. Spravato must be administered in a certified healthcare setting with mandatory post-dose monitoring.

This article is educational and does not constitute medical advice. Eligibility for ketamine-assisted therapy should be assessed by a qualified clinician familiar with your history.

About the author

Reverdi Darda, RN, BScN — Reg #61707 | CEO & Founder, ATMA CENA

Reverdi Darda, RN is CEO & Founder of ATMA CENA and a Registered Nurse with over three decades of experience in healthcare operations, community engagement, policy development, and strategic planning. A recognized leader in mental health access, Reverdi has dedicated her career to advancing evidence-based treatment models and advocating for policy change that prioritizes effective care. She founded ATMA CENA to expand practitioner and public access to psychedelic-assisted therapy across Canada.

Sources

1. Swainson J, et al. (2021). CANMAT racemic ketamine task force recommendations. Can J Psychiatry. https://pubmed.ncbi.nlm.nih.gov/33174760/
2. Singh JB, et al. (2016). Twice-weekly vs thrice-weekly IV ketamine in TRD. Am J Psychiatry. https://pubmed.ncbi.nlm.nih.gov/27056608/
3. Phillips JL, et al. (2019). Single, repeated, and maintenance IV ketamine for TRD. Am J Psychiatry. https://pubmed.ncbi.nlm.nih.gov/30764648/
4. Wan LB (Murrough JW), et al. (2015). Safety and tolerability of IV ketamine — pooled analysis of 205 infusions. J Clin Psychiatry. https://pubmed.ncbi.nlm.nih.gov/25271445/
5. Daly EJ, et al. (2019). SUSTAIN-1 — esketamine maintenance of efficacy (relapse prevention). JAMA Psychiatry. https://pubmed.ncbi.nlm.nih.gov/31166571/
6. Wajs E, et al. (2020). SUSTAIN-2 — esketamine long-term safety, 1 year, 802 patients. J Clin Psychiatry. https://pubmed.ncbi.nlm.nih.gov/32316080/
7. Yermus R, et al. (2024). Canadian real-world KAP effectiveness — durability at 3 and 6 months. Psychedelic Med. https://pubmed.ncbi.nlm.nih.gov/40051583/
8. Andrashko V, et al. (2020). Benzodiazepine attenuation of IV ketamine antidepressant effect. Front Psychiatry. https://pubmed.ncbi.nlm.nih.gov/33005153/
9. Anand A, et al. (2023). ELEKT-D: ketamine vs ECT for non-psychotic TRD, n=403. N Engl J Med. https://pubmed.ncbi.nlm.nih.gov/37224232/

Related articles

• Ketamine Therapy Cost in Canada
• Ketamine for Depression in Canada
• Psychedelic-Assisted Therapy at ATMA CENA
• The CoCare Model