What the evidence shows about timing
Major guidelines and reviews — including Cochrane efficacy reviews — describe most clinically meaningful response as appearing between four and twelve weeks at an adequate dose. RANZCP and NICE both recommend a minimum trial of four to six weeks before assessing response. Early response within two weeks is documented for a subset of patients but is not the typical pattern. Absence of response in the first three weeks is not evidence the medication will not work.
What 'working' tends to look like in practice
The early signs described in patient resources and clinical literature are small and easy to miss in real time. Common patterns include:
Less reactivity. Small frustrations bother you less than they used to. Not the absence of emotion — just a lower amplitude on the difficult ones.
Quieter background anxiety. The constant low hum is not always present. This is usually the first shift people notice, and it often shows up before mood changes do.
Slightly more capacity for things that had felt impossible. Replying to a message, leaving the house, picking up a book. Not motivation — capacity.
Sleep settling. Fewer wake-ups, less rumination overnight. Sleep is often the earliest signal, and it precedes mood change by a week or two.
Appetite returning to something closer to normal. Either direction — returning after suppression, or settling after increase.
Crying less without trying. Or crying when something is sad, instead of all the time. The quality of the emotion normalises before its absence is felt.
Others often notice before you do
Royal College of Psychiatrists patient information notes that people around the patient often notice these changes before the patient does. A partner, family member, or close friend may say "you seem more like yourself" before that thought would occur to you.
What does not count as evidence
Side effects easing is not evidence the medication is working — side effects typically ease by week three regardless of whether the mood response is occurring. A single good day is not evidence; everyone has good days. The signal is in the average over a week or two, not in any individual day.
A simple tracking practice the guidelines support
Patient self-tracking is endorsed across NICE, RANZCP, and Royal College of Psychiatrists resources as a useful adjunct to follow-up care. A practical version: three lines a day for six weeks — sleep, body, mood. One sentence per week summarising what the week as a whole felt like. After six weeks, the trajectory becomes legible:
Side effects typically emerge and peak. Sleep may be disrupted. Anxiety can increase. This is an expected part of the adjustment — not evidence the medication is wrong.
Side effects typically begin to ease. Sleep often starts to settle. Body-level changes — appetite, energy — may be the first positive shifts.
Mood (if responding) typically shifts here. Reactivity softens. Background anxiety quietens. The changes are usually gradual — recognisable in retrospect more than in real time.
By week six, the trajectory is usually legible. If neither side effects nor mood have shifted, this is the right time to raise it with your prescriber — not before, and not by stopping.
When to talk to your prescriber
Talk to your prescriber if any of these apply
- By week six to eight if there has been no meaningful change at all.
- Side effects are intolerable and not easing after two to three weeks.
- New suicidal thoughts develop at any point — do not wait for a scheduled appointment.
- You cannot tell whether it is working — bring your tracking and ask. That is exactly what follow-up appointments are designed for.
Frequently asked questions
What is the earliest an antidepressant can start working?
Some patients report early subtle changes in the second or third week, but this is not the typical pattern. Major guidelines including NICE and RANZCP describe the first meaningful response as typically appearing between weeks four and six.
Is feeling worse a sign the medication will not work?
Not necessarily. The first one to two weeks often involve side effects and sometimes increased anxiety before any benefit. Multiple major guidelines describe this as a known transient pattern. Persistent worsening beyond week two to three is worth raising with your prescriber.
Should I keep a journal to track my response?
Yes — patient self-tracking is endorsed in RANZCP, NICE, and Royal College of Psychiatrists patient resources as useful for both the patient and the prescriber. Three lines a day on sleep, body, and mood is typically enough to make the next appointment more productive.
Related articles
Evidence and sources referenced
- RANZCP — Clinical Practice Guidelines for Mood Disorders.
- NICE Guideline NG222 — Depression in adults: treatment and management.
- NPS MedicineWise — patient resources on antidepressant response.
- Royal College of Psychiatrists — patient information on antidepressants.
- Cochrane Library — antidepressant efficacy reviews.
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