Ketamine therapy for depression has grown rapidly over recent years, with hundreds of clinics now offering it across the US. Its reputation as a fast-acting treatment for even severe, treatment-resistant depression has drawn significant attention from both patients and clinicians.
However, while ketamine can provide rapid relief, it is not simply a “quick fix.” Understanding how it works, how long its effects last, and how treatment schedules are structured is essential for setting realistic expectations and maximizing long-term benefits.
How Quickly Does Ketamine Start Working for Depression?
Ketamine can begin working for depression much faster than traditional antidepressants, with many patients reporting mood improvement within hours of treatment.
Research shows that ketamine’s antidepressant effects often emerge within 24 hours, especially for people with treatment-resistant depression who have not responded to SSRIs or other medications that typically take weeks to kick in. That said, how quickly ketamine works can vary based on the type of treatment and the individual [1].
Does Ketamine Administration Method Make A Difference?
Different ketamine administration methods vary significantly in bioavailability, onset speed, and control, impacting their speed and effectiveness for mental health treatments like depression. IV ketamine offers nearly 100% bioavailability for rapid results, while nasal and oral routes have lower absorption rates and slower effects [2].
| Administration Method | Bioavailability | Onset Time | Best For |
| IV | Nearly 100% | Instantly or in a few minutes | Rapid relief |
| Nasal | 8% to 50% | 30 to 60 minutes | Non-invasive option |
| Oral | 17% to 29% | Hours | Non-invasive, at-home convenience |
| IM Injection | 93% | 5 to 30 minutes | Quick relief |
How Long Do the Antidepressant Effects of Ketamine Typically Last?
For many patients, the antidepressant effects of a single ketamine treatment last anywhere from several days to one or two weeks. Most providers recommend an initial series of treatments, often six sessions over two to three weeks, to help reinforce and stabilize the brain changes made by ketamine.
After this initial phase, patients may transition to maintenance or “booster” treatments spaced weeks or months apart, depending on how long relief lasts for them individually. Compared to standard antidepressants, which require daily dosing and can take four to eight weeks to show benefit, ketamine offers rapid relief but usually requires ongoing, carefully monitored sessions to maintain its effects over time.
Does Ketamine Work Longer After Multiple Treatments?
Yes, for many patients, ketamine’s antidepressant effects can become more noticeable after several treatments. Through repeated exposure, ketamine can reduce rigid thought patterns, emotional blocks, and “learn” healthier patterns of thinking.
Research suggests that patients who complete the full initial series tend to experience more sustained benefits compared to those who rely on a single session. However, the exact duration varies based on factors such as metabolism, depression severity, and overall health, so providers tailor follow-up schedules to individual needs [3].
How Maintenance Ketamine Treatments Extend Results
Maintenance ketamine therapy involves periodic follow-up sessions after the induction phase to help sustain the antidepressant benefits, prevent relapse, and reinforce neural pathways that were strengthened during initial treatment.
The frequency of maintenance treatments varies depending on individual response and clinical guidance. Some patients benefit from sessions every 2–4 weeks, while others may need them every few months.
During maintenance, patients often report not only prolonged relief of depressive symptoms but also improvements in energy, focus, and overall emotional resilience. Maintenance therapy shifts ketamine from a short-term intervention into a sustainable tool for managing depression over months or even years [4].
Why Does Ketamine Work Longer for Some People Than Others?
Like with any medication, the effects of ketamine can vary for the individual, based on several factors such as metabolism, genetics, brain chemistry, and severity of depression.
Factors that can affect the duration of ketamine treatment include:
- Brain Chemistry: Some people have more responsive synaptic networks, allowing the antidepressant effects of ketamine to work longer.
- Severity of Depression: People with treatment-resistant depression may need more frequent sessions to maintain the effects.
- Co-occurring Health Conditions: People with neurological disorders such as epilepsy, heart conditions, high blood pressure, or autoimmune conditions that affect brain function may not be considered candidates for treatment.
- Medications: Benzodiazepines, anticonvulsants, antipsychotics, and certain enzyme modulators may affect the metabolism of ketamine or alter brain receptor activity.
- Lifestyle: Quality and quantity of sleep, stress levels, and drug or alcohol use can influence the effectiveness of ketamine and how long it works.
- Consistency of Treatment: It’s important to complete a full induction treatment phase and follow up with maintenance sessions (if recommended by your provider). Always tell your provider about any noticeable changes or if you are failing to see improvements, as they may need to tailor your protocol (e.g, more frequent sessions, integrated therapy alongside ketamine).
Ketamine Therapy for Treatment-Resistant Depression in Utah
If you’ve already tried conventional methods of mental health treatment with no relief, ketamine may be an ideal option for you. At Harper Clinic Utah, we provide personalized treatment planning and licensed ketamine therapy to address deep-rooted depression, trauma, and emotional blocks.
We require clients receiving ketamine therapy to also be in traditional therapy, either with one of our therapists or an outside provider. Contact our consultation team to learn if you are a good candidate for ketamine assisted therapy today.
Sources
[1] Grant, S. et al. (1982). Bioavailability, pharmacokinetics, and analgesic activity of ketamine in humans. Journal of Pharmaceutical Sciences, 71(5), 539–542.
[2] Amore, M. et al. (2014). The role of ketamine in treatment-resistant depression: a systematic review. Current neuropharmacology, 12(5), 444–461.
[3] Brzostek, T. et al. (2020). Efficacy of single and repeated administration of ketamine in unipolar and bipolar depression: a meta-analysis of randomized clinical trials. Pharmacological reports : PR, 72(3), 543–562.
[4] Knyahnytska, Y. et al. (2026). Efficacy and safety of ketamine maintenance therapy in treatment-resistant depression: A systematic review of treatment protocols and clinical outcomes. Journal of affective disorders, 394(Pt A), 120475.