Most people start with 4 to 8 ketamine sessions over two to four weeks, then taper to less frequent maintenance treatments if they respond well. The exact number depends on which form of ketamine you receive, how severe your depression is, and how quickly you improve. There is no single fixed number that works for everyone, but clinical protocols follow a fairly consistent pattern.
The Induction Phase: 4 to 8 Sessions
Ketamine treatment for depression typically begins with an intensive “induction” phase designed to build up the antidepressant effect. For IV ketamine infusions, this means 4 to 8 sessions spread over one to four weeks. Clinics commonly schedule these two or three times per week. The goal is to give ketamine enough repeated exposure to trigger lasting changes in how your brain processes mood, not just the temporary lift that a single dose provides.
Not everyone responds on the first try. In one controlled trial of six infusions given three times a week, only 3 out of 14 patients responded after the first infusion, and just 1 achieved remission. But as the course progressed, 11 of the 12 patients who completed all six sessions responded, and 8 reached remission. The median number of infusions patients needed before meeting response criteria was three, and 77% of responders required three or more sessions to get there. So if you don’t feel dramatically better after one or two treatments, that doesn’t mean ketamine won’t work for you.
How the Spravato (Esketamine) Schedule Differs
Spravato, the FDA-approved nasal spray form of esketamine, follows a more structured timeline. During the first four weeks, you receive treatments twice per week, totaling eight sessions. From weeks 5 through 8, the frequency drops to once per week. After week 9, treatments move to every other week, or remain weekly if needed. The prescribing guidelines are clear that the goal is to find the least frequent dosing schedule that keeps your symptoms in check.
For people with major depression and active suicidal thoughts, the FDA-approved schedule is more focused: twice per week for four weeks (eight sessions total), after which your provider evaluates whether continuing treatment makes sense. The use of Spravato beyond that four-week window hasn’t been formally studied for this specific indication.
What Happens After the Initial Course
The induction phase is only the beginning. If ketamine works for you, the relief often fades within days to weeks after your last session. That’s where maintenance or “booster” treatments come in. In clinical trials, responders who completed an initial six-infusion course were moved to once-weekly sessions for an additional four weeks to see if the benefits held. The idea is to gradually stretch the interval between sessions while monitoring whether symptoms return.
Over time, many patients settle into a pattern of one treatment every two to four weeks. Some need sessions more frequently, while others can go longer between appointments. A consensus statement published in JAMA Psychiatry recommends that if treatments can’t be spaced out to at least once per week by the second month, discontinuation should be considered. The principle across all guidelines is the same: use the fewest sessions necessary to maintain your response.
When to Expect Results
Ketamine is often described as fast-acting, and it is compared to traditional antidepressants, which can take four to six weeks. Some people notice a shift in mood within hours of their first infusion. But a more realistic expectation is that meaningful, sustained improvement takes three to six sessions. Early studies showed dramatic responses to a single IV dose, but follow-up research found that many initial non-responders converted to responders with repeated sessions.
The speed of your response shapes the total number of treatments you’ll need during induction. If you respond strongly by session three, your provider may not push to six or eight. If improvement is gradual, the full course gives the treatment more time to take hold.
Factors That Affect How Many Sessions You Need
Several variables influence whether you’ll need more or fewer treatments. The most significant is how long your current depressive episode has lasted. In one study, patients who didn’t respond to ketamine had significantly longer episode durations than those who did. A depression that has persisted for years may be harder to shift than one that’s lasted months.
The depth of treatment resistance also matters. Patients in clinical trials had typically failed an average of 3.3 antidepressant medications and nearly 3 augmentation strategies before trying ketamine. About 22% hadn’t responded to electroconvulsive therapy (ECT) in their current episode. Roughly a quarter had co-occurring anxiety disorders like social phobia, agoraphobia, or generalized anxiety. All of these factors can influence how many sessions it takes to see improvement, and some patients with highly resistant depression may need the full 8-session induction course plus ongoing maintenance.
If you’re receiving IV ketamine at a clinic rather than FDA-approved Spravato, the schedule may vary more. IV protocols haven’t been standardized the way Spravato has, and expert consensus acknowledges that firm recommendations on the ideal number and frequency of sessions aren’t yet possible. Your provider will likely adjust the plan based on how you’re responding week to week.
What “Not Responding” Looks Like
There’s no universally agreed-upon cutoff for when to stop trying ketamine if it isn’t working. With Spravato, providers can increase session frequency back to weekly if depression scores remain elevated after the initial taper, then reassess a few weeks later. For IV ketamine, the JAMA Psychiatry consensus panel suggested that if you can’t reduce dosing to at least once a week within two months, the treatment should probably be discontinued.
In practical terms, most clinicians evaluate your progress after the initial induction course of 4 to 6 sessions. If there’s been no meaningful improvement by that point, continuing treatment is unlikely to produce a breakthrough. That said, the decision is individualized. A partial response might justify a few more sessions, while a complete lack of change typically signals it’s time to explore other options.