The most common reason a good antidepressant gets abandoned is a mismatch in expectations. Side effects tend to arrive first and benefit arrives later, so week two can feel like proof the medication is not working when it is simply early.
Here is the timeline most people follow, and the specific points where you should contact your prescriber instead of waiting for the next appointment.
Week 1: adjustment, not improvement
The first week is about tolerating the starting dose. Mild nausea, headache, looser stools, vivid dreams, drowsiness, or jitteriness are common and usually fade within seven to fourteen days. Taking the dose with food, or shifting it to morning or evening, resolves a lot of it.
Mood typically has not changed yet. That is expected — nothing has gone wrong.
Weeks 2–3: early signals
The first genuine improvements are rarely in mood. Sleep steadies, appetite returns, and getting started on tasks takes a little less effort. People around you sometimes notice before you do.
This is also when most starting-dose side effects fade. If they have not, that is worth a call — a dose adjustment or a switch is reasonable rather than something to endure.
Weeks 4–6: the real assessment window
By week four to six on an adequate dose, there should be measurable movement: fewer bad days, shorter low periods, more interest in things you had stopped doing. If there is none, the dose is usually increased, and this is the normal point for that decision.
Reaching an effective dose sometimes takes two or three step-ups. A medication has not failed until it has had an adequate dose for an adequate time.
Weeks 6–8: full response and next decisions
Most people who respond to a given antidepressant see the bulk of the benefit by week eight. If response is partial, options are to increase further, add a second agent, or switch classes — all reasonable, and none of them a failure on your part.
About a third of people do not respond well to the first medication tried. Response to a second or third is common, which is why follow-up visits matter more than the initial choice.
- Full response: continue for at least six to twelve months before considering a taper
- Partial response: dose increase, augmentation, or switch
- No response at an adequate dose: switch, and revisit the diagnosis
When to call sooner
Some things should not wait for the next scheduled visit.
- New or worsening thoughts of self-harm — call immediately, or call or text 988
- Unusually elevated mood, racing thoughts, or a sharp drop in the need for sleep
- Rash, fever, severe agitation, muscle rigidity, or confusion
- Side effects that have not eased after two weeks
- You are considering stopping — stopping abruptly causes discontinuation symptoms
Common questions
How long do antidepressants take to work?
Early changes in sleep, appetite, and energy often appear within two to three weeks. Meaningful mood improvement is usually assessed at four to six weeks on an adequate dose, with full response by around eight weeks.
Are the side effects permanent?
Most early side effects — nausea, headache, drowsiness, jitteriness — fade within one to two weeks. Persistent effects such as sexual side effects or sleep changes should be reported; a dose change or different medication usually resolves them.
Can I stop once I feel better?
Stopping early is the most common cause of relapse. Continuing six to twelve months after you feel well, then tapering slowly with your prescriber, gives the best odds of staying well.
Side effects come first, benefit comes later — judge an antidepressant at week six on an adequate dose, not at week two.
This article is general education, not medical advice. If you are in crisis, call or text 988.