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People respond differently to antidepressants. Some notice side effects early and improvement later; some have few side effects; and some need to review or change the plan.
Before the first dose
You and the prescriber should agree what you hope the medicine will help, how to take it, likely side effects, when it will be reviewed and what to do if your symptoms or safety worsen.
Tell the prescriber about other medicines and supplements, pregnancy or breastfeeding, alcohol or drug use, previous antidepressants, bipolar disorder or episodes of unusually high energy, reduced need for sleep or impulsive behaviour.
A realistic timeline
Nausea, headache, sleep disturbance, tiredness, agitation or a temporary increase in anxiety can occur. Ask a pharmacist or prescriber if you are uncertain.
There should usually be an early review. It may still be too soon to judge the full benefit, but side effects, safety and how you are coping matter.
NICE says that if an antidepressant is going to help, an effect is usually seen within four weeks. Improvement may be gradual rather than dramatic.
If benefit is limited or side effects are difficult, the plan can be reviewed. Do not increase, change or stop the medicine without advice.
What improvement might look like
The first useful change is not always suddenly feeling happy. It might be sleeping a little better, experiencing less panic, managing basic tasks, having more space around difficult thoughts or beginning to reconnect with people and activities.
Agreeing two or three personal signs of improvement can make reviews more meaningful than relying on a score alone.
Side effects deserve an honest conversation
Possible effects include nausea, headache, tiredness, sleep disturbance, sweating, dry mouth, changes in weight or appetite, sexual difficulties and emotional blunting. Different medicines have different profiles, and individual experience varies.
You do not have to silently tolerate a side effect that matters to you. The prescriber may discuss waiting, changing when you take it, adjusting the dose, switching medicine or choosing another approach.
Seek help promptly if you feel worse
Contact the prescriber promptly if agitation, severe restlessness, unusual behaviour, worsening mood or suicidal thoughts appear after starting or changing a dose. NICE recommends a review one week after starting for people aged 18–25 or when there is particular concern about suicide risk; other adults will usually have an initial review within two weeks.
Use NHS 111’s mental-health option if you need urgent help. Call 999 or go to A&E if there is immediate danger.
How long might treatment continue?
If the medicine is helping, treatment often continues for at least six months after symptoms have improved. Some people benefit from longer treatment because of recurrent or severe illness. This should be reviewed rather than assumed to be permanent.
Withdrawal is real—and can usually be managed
Antidepressants do not cause a high or cravings in the way addictive drugs do, but the body can adapt to them. Missing doses, stopping suddenly or reducing too quickly can cause withdrawal symptoms.
A 2024 systematic review estimated that, after allowing for non-specific symptoms also seen with placebo, withdrawal symptoms affected roughly one in six to seven people stopping antidepressants. Risk and severity varied between medicines and individuals. Other studies and patient experience show that some people have more difficult or prolonged symptoms.
Possible symptoms include dizziness, nausea, sleep disturbance, anxiety, irritability, low mood and electric-shock sensations. Speak to the prescriber and reduce in stages at a pace that fits your response.
Keep these points
- Take the medicine as agreed and check before combining it with other medicines or supplements.
- Early side effects do not necessarily predict whether it will help, but they still deserve attention.
- Know when your first review will happen and what improvement you hope to see.
- Seek help promptly if your mental state or safety worsens.
- Do not stop suddenly; agree a gradual plan with the prescriber.
Evidence and official guidance
NICE NG222: starting and stopping antidepressants
The Lancet Psychiatry 2024: antidepressant discontinuation symptoms
First published July 2026. Last reviewed: 30 October 2026. Planned review: 30 April 2027.
Prepared for the Pathfields Healthy Living Portal using current NICE and NHS guidance and recent peer-reviewed evidence.