Spravato can begin working within 24 hours of the first dose, and in trials the difference from placebo was measurable by day two. Most responders show clear improvement by the end of the four-week induction phase, typically in weeks two to three. If there is no improvement at all after four weeks, it is time to reassess.
The honest answer to "how long does Spravato take to work" is that it depends on which patient you are, and that the range runs from the first afternoon to the fourth week. I tell patients two things at the start: the speed is real and it is the reason this treatment exists, and the speed is also uneven, so the first session is not the test.
What the trials showed
Spravato's approval rested on the TRANSFORM trials, in which adults with treatment-resistant depression received either esketamine or placebo nasal spray, both alongside a newly started oral antidepressant, twice weekly for four weeks.
In TRANSFORM-2, the difference between esketamine and placebo on the depression rating scale was already statistically meaningful at day two, roughly 24 hours after the first dose. That is the basis for the "rapid" claim. By day 28, the end of induction, about 69 percent of esketamine patients had responded (a 50 percent or greater drop in symptoms) versus about 52 percent on placebo plus antidepressant, and about 53 percent had reached remission versus 31 percent.
Those placebo numbers are high because everyone in the trial also started a new antidepressant, which works on its own over four weeks. The esketamine-specific effect is the gap, and it was present early and widened through the month.
In the ASPIRE trials, which supported the 2020 approval for major depression with acute suicidal ideation, the primary measurement was at 24 hours after the first dose, and esketamine beat placebo on that measure. That is the strongest evidence for a next-day effect, in the most acutely ill population.
A week-by-week timeline
With the caveat that individual patterns vary, here is how induction usually unfolds.
| Period | Sessions | What patients commonly report |
|---|---|---|
| First 24 hours | Session 1 | Tiredness, sometimes a noticeable lightening of mood or relief from hopelessness that lasts a day or two. Some feel nothing beyond the session effects. |
| Week 1 | Sessions 1 and 2 | Brief improvements after each dose that may fade before the next. Sleep sometimes improves first. |
| Week 2 | Sessions 3 and 4 | Improvements start to hold between sessions. Less rumination, more energy. Family members often notice before the patient does. |
| Week 3 | Sessions 5 and 6 | The most common point for clear, sustained improvement. Rating scale scores drop meaningfully. |
| Week 4 | Sessions 7 and 8 | End of induction. Responders are usually evident. Late responders sometimes turn the corner here. |
| Weeks 5 to 8 | Weekly | Consolidation. Gains deepen and stabilize for responders. |
| Week 9 onward | Weekly or every 2 weeks | Maintenance. Frequency set by how well the response holds. |
Why some people respond immediately and others slowly
Esketamine acts on glutamate signaling rather than serotonin, and its downstream effects involve rapid changes in synaptic connections. That is why it can work in hours rather than weeks. But the first dose is 56 mg, the lowest, and many patients need 84 mg for a full effect; the dose is adjusted at the second session based on tolerability. Depression that has lasted years with heavy rumination also tends to take longer to shift than a more acute episode. And the oral antidepressant you take alongside Spravato is contributing its own slower effect.
Patients who feel an immediate lift are not guaranteed a durable response, and patients who feel nothing in week one are not destined to fail. In my experience the week three mark is the most informative single point.
How to tell if it is working
We measure, rather than guess. Every session begins with a brief rating scale, usually the PHQ-9, and we chart the trend. Signs that Spravato is working include:
- Scores falling across consecutive sessions, not just bouncing after each dose.
- Improvements that last through the days between sessions.
- Returning interest in activities, not just reduced sadness.
- Better sleep and appetite.
- Fewer or less intense thoughts of death or hopelessness.
- People close to you noticing a change.
A single good afternoon after a session is encouraging but is not the measure. The measure is the trajectory over weeks.
When to reassess
If after four weeks of induction there has been no measurable improvement at all, continuing at the same dose is unlikely to help, and we reassess. Options at that point include confirming the dose reached 84 mg, reviewing the oral antidepressant, re-examining the diagnosis (bipolar depression and untreated medical contributors are common findings), and considering Deep TMS or another path.
If there has been partial improvement, continuing into weeks five to eight is reasonable, because some patients consolidate a response during the weekly phase. The FDA label is explicit that continued treatment should be re-evaluated periodically based on benefit.
How long the effect lasts between doses
Early in treatment, the antidepressant effect of a dose may fade within a few days, which is why induction is twice weekly. As treatment continues, the effect holds longer, which is why frequency decreases. By maintenance, most responders hold their improvement for one to two weeks between doses. The SUSTAIN-1 trial showed that stopping Spravato after remission roughly doubled the relapse rate compared with continuing, which is the evidence base for ongoing maintenance.
Factors that speed or slow response
A few patterns show up often enough to mention. Patients whose depression is acute, meaning this episode began within the past year or two, tend to respond faster than those with chronic, decade-long illness. Patients with prominent anxiety sometimes take longer because the early sessions are dominated by managing the dissociation rather than settling into it. Heavy alcohol use between sessions and benzodiazepines on the morning of treatment both appear to blunt and delay the effect. Reaching the 84 mg dose at session two, when tolerated, shortens the time to response for many patients.
None of these are rules. They are reasons we review the whole picture at week two rather than waiting passively for week four.
What a partial response looks like
Not every response is clean. A common pattern is a 30 to 40 percent drop in rating scale scores by week four: real improvement that falls short of the 50 percent threshold for formal response. Partial responders usually continue into the weekly phase, where some cross the threshold, and we look at the oral antidepressant and dosing as levers. A partial response at week four is a reason to adjust, not to stop.
The oral antidepressant matters
Spravato is approved for use with an oral antidepressant, not instead of one. In the trials, patients started a new antidepressant at the same time as esketamine. In practice, patients who come to us already on an antidepressant usually continue it. The oral medication contributes to the overall response and to maintaining it, and it is one of the levers we adjust if the response is partial.
Bottom line
Spravato works faster than any oral antidepressant, with measurable effects within a day for some patients, but the reliable signal comes over the four-week induction, most often around week three. Judge it by the trend on a rating scale, not by any single session, and expect a reassessment at four weeks if nothing has moved.
Frequently asked questions
Can Spravato work after the first dose?
Yes, for some patients. In the ASPIRE trials, esketamine reduced depressive symptoms measurably within 24 hours of the first dose in patients with acute suicidal ideation. For many others, the first clear improvement comes in week two or three. An absent first-dose effect does not predict failure.
How many Spravato sessions before it works?
Most responders show meaningful improvement by sessions five to six, in the third week of induction. The full induction phase is eight sessions over four weeks, and that is the standard point to judge response. Some patients consolidate their response during the weekly phase afterward.
What if Spravato is not working after four weeks?
If there is no measurable improvement after the eight-session induction, continuing unchanged is unlikely to help. Your psychiatrist will confirm the dose reached 84 mg, review the oral antidepressant and diagnosis, and consider alternatives such as Deep TMS. Partial responders may benefit from continuing into weeks five to eight.
How long does Spravato stay in your system?
Esketamine is cleared quickly; the dissociative effects resolve within about two hours and the drug's blood levels fall substantially within a day. The antidepressant effect, which depends on downstream brain changes rather than drug levels, lasts days to weeks and lengthens with continued treatment.
Related reading
- What Does a Spravato Session Feel Like?
- Spravato Side Effects and Who Should Not Take It
- Why Spravato Did Not Work for Some People, and What That Means for You
- How Long Do Antidepressants Take to Work?
This article is educational and does not replace evaluation by a licensed clinician. If you are in crisis, call or text 988.