Switching antidepressants: what actually happens, and what the dose chart means
Direct switch, cross-taper or washout: how each approach works, what the equivalent dose chart does and doesn't tell you, and what the first six weeks usually look like.
By Tanya Rybakova · Medically reviewed by Dr. Jason Tan, Consultant Psychiatrist · 2026-09-18 · 16 min read
Key takeaways
- Only around one in three people reach remission on the first antidepressant they try. Switching is common and is not a sign that treatment has failed.
- There are three ways to switch: a direct switch, a cross-taper, or a washout. Which one is right depends on the medicines involved; fluoxetine and MAOIs need special handling.
- The equivalent dose chart is a group-level guide drawn from clinical trials, not a conversion rule. Your prescriber sets the dose.
- In the first days, withdrawal from the old medicine and start-up effects from the new one can overlap. For most people these settle within one to two weeks.
- Judge the new antidepressant at around four to six weeks, and seek urgent help for warning signs of serotonin syndrome or any thoughts of self-harm.
Switching antidepressants can be a challenging and sometimes confusing process. This may involve gradually reducing one medication while introducing another. Each antidepressant has its own dosing schedule, side effect profile, and rate of elimination from the body.
Many guides explain the switching methods a prescriber may use but provide little detail about what to expect during the days and weeks that follow. This article examines both the clinical approaches and the practical experience of changing medications. It also addresses a question of if you are taking a particular dose of one antidepressant, is there an equivalent dose of another?
Why people switch antidepressants
The first antidepressant a person tries is not always the one they continue taking. STAR*D, one of the largest studies of antidepressant treatment, found that approximately one in three participants achieved remission with their initial medication, while around half experienced a meaningful improvement. For many people, this means trying a different treatment.
This should not be viewed as a personal failure or as evidence that treatment has failed. There is currently no reliable test that can predict which antidepressant will work best for a particular person. Finding the most suitable medication often involves a process of careful trial, review and adjustment.
People switch antidepressants for several common reasons:
- Persistent side effects. These may include sexual difficulties, emotional blunting, weight changes and disrupted sleep.
- Limited or diminishing benefit. The medication may not have provided enough relief, or it may have become less effective over time.
- Pregnancy or plans to become pregnant. The amount and quality of pregnancy safety data vary between antidepressants, which may influence treatment decisions.
- Interactions with other medicines. Starting a new medication for an unrelated condition may make the current antidepressant less suitable.
- Cost, supply or availability. Practical considerations are valid reasons for reviewing treatment.
People should not feel that they need to defend their reasons for considering a change. Understanding what to expect can make the transition more manageable and help distinguish between normal adjustment effects and signs that medical advice is needed.
Three approaches to switching antidepressants
There is no single way to switch from one antidepressant to another. The approach your prescriber recommends will depend on the medicines involved, your current dose, how long you have been taking it and how you have responded to treatment. The three main approaches are a direct switch, a cross-taper and a washout.
These descriptions explain the general principles. The precise schedule should always be agreed with your prescriber.
Direct switch
A direct switch involves stopping the first antidepressant and starting the second, usually the following day. It may be suitable when the two medicines have similar effects and taking them together could create unnecessary risks.
This approach is commonly used when switching between certain SSRIs. The new medication may help reduce withdrawal symptoms from the first, although some people still experience temporary symptoms while their body adjusts.
Cross-taper
During a cross-taper, the dose of the first antidepressant is gradually reduced while the second is introduced and increased. This can often be carried out cautiously over two to four weeks, although the timing should be adjusted according to the person’s response and tolerability.
The main advantage is continuity of treatment. However, the period of overlap may produce side effects from both medicines, which can make it difficult to identify what is causing a particular symptom. Keeping a brief daily record of sleep, mood, physical symptoms and anything unusual can provide useful information for your prescriber.
A cross-taper is not suitable for every combination, particularly when the medicines could interact.
Washout
A washout involves gradually reducing and stopping the first antidepressant, then waiting for a specified period before starting the second. This is necessary when the two medicines must not overlap because of the risk of a serious interaction.
Monoamine oxidase inhibitors, or MAOIs, are an important example. This group includes phenelzine and tranylcypromine. Combining an MAOI with an SSRI or SNRI can increase the risk of serotonin syndrome, a rare but potentially serious reaction. Switching to or from an MAOI is complex and should be managed with specialist advice. Cross-tapering is not recommended because of the high risk of serotonin syndrome.
Fluoxetine requires particular care because it and its active metabolite remain in the body much longer than most other antidepressants. After fluoxetine has been stopped, the recommended wait before starting an MAOI is five to six weeks. When switching from fluoxetine to another SSRI or SNRI, it is generally recommended to reduce the dose to 20 mg, stopping it and waiting four to seven days before starting the new medication at a low dose.
If the waiting period in your switching plan seems unusually long, it is often because the first medication remains active in the body and could interact with the new one.
Understanding the antidepressant equivalent dose chart
A common question when switching antidepressants is usually some version of, “If I take 50 mg of sertraline (Zoloft), what dose of escitalopram (Lexapro) is equivalent?” This is known as dose equivalence, an estimate of how the usual doses of different antidepressants compare.
The chart below should be treated as a general guide, not as a conversion calculator. Its figures are based on research comparing the average doses used in flexible-dose clinical trials. They reflect prescribing patterns across groups of participants, not the dose that will be appropriate for a particular person.
Responses to antidepressants vary considerably. Two people taking the same dose of the same medication may experience very different benefits, side effects and withdrawal symptoms. For this reason, a prescriber will not usually calculate a new dose using a simple formula. The starting dose and switching schedule will depend on the medicines involved, the reason for the change, possible interactions and how the individual responds.
The purpose of the chart is to provide context for the dose recommended by your prescriber. It should not be used to change medication or calculate a new dose without medical guidance.
Antidepressant equivalent doses (orientation only)| Medicine | Type | Reference dose | Usual daily dose for depression | Notes |
|---|
| Fluoxetine (Prozac) | SSRI | 20 mg | UK and US: 20 to 60 mg | The comparison point for the others. Stays in the body far longer than any other antidepressant in common use, which changes the rules when you come off it. |
|---|
| Sertraline (Zoloft, Lustral) | SSRI | 50 mg | UK and US: 50 to 200 mg | Figure supported by the trial-based analysis. |
|---|
| Escitalopram (Cipralex, Lexapro) | SSRI | 10 mg | UK and US: 10 to 20 mg. UK maximum 10 mg if over 65. | Figure supported by the trial-based analysis. |
|---|
| Citalopram (Cipramil, Celexa) | SSRI | 20 mg | UK and US: 20 to 40 mg. Maximum 20 mg if over 65. | Not covered by the trial-based analysis. Treat this figure as custom and practice, not evidence. |
|---|
| Paroxetine (Seroxat, Paxil) | SSRI | 20 mg | UK and US: 20 to 50 mg | The trial-based figure is nearer 17 mg. Leaves the body fastest of the common SSRIs, so withdrawal symptoms tend to arrive sooner and feel sharper. |
|---|
| Venlafaxine (Efexor, Effexor) | SNRI | 75 mg | UK: 75 to 375 mg. US (extended release): 75 to 225 mg. | Figure supported by the trial-based analysis. Withdrawal symptoms are among the most commonly reported. |
|---|
| Duloxetine (Cymbalta) | SNRI | 30 mg | UK: 60 to 120 mg. US: 40 to 120 mg. | Not covered by the trial-based analysis. In the UK, 30 mg is a step on the way up, not a treatment dose for depression. |
|---|
| Bupropion (Wellbutrin) | NDRI | 150 mg | US: 150 to 450 mg. Not licensed for depression in the UK. | Works on different brain chemicals from the SSRIs and SNRIs, so any comparison is loose. UK prescribing for depression would be off licence. |
|---|
| Vortioxetine (Brintellix, Trintellix) | Multi-target | 10 mg | UK and US: 5 to 20 mg | Not covered by the trial-based analysis. Came into use after it was done. |
|---|
| Mirtazapine (Zispin, Remeron) | NaSSA | 15 mg | UK and US: 15 to 45 mg | The trial-based figure is nearer 25 mg. Works differently again, so comparison is loose. |
|---|
These figures are for orientation only. They are not a prescription and not a conversion rule. The dose that is right for you depends on your history and your response and is a decision for your prescriber.
A few points are important when interpreting the chart:
Some estimates are more certain than others. The underlying analysis included bupropion and mirtazapine, despite their pharmacological differences from SSRIs and SNRIs. This does not make the comparisons invalid, but they remain approximate, group-level estimates. Citalopram, duloxetine and vortioxetine were not included in the same analysis. Any values shown for these medicines are based on commonly used clinical doses rather than the study’s pooled calculations.
Paroxetine has a relatively high risk of withdrawal symptoms. It leaves the body more quickly than many other SSRIs, so withdrawal symptoms may begin sooner and can be more difficult for some people. NICE guidance advises particular care when reducing paroxetine. A slower, individualised taper may be needed, especially if withdrawal symptoms develop.
Fluoxetine behaves differently because it remains in the body for much longer. Its prolonged action can make withdrawal less abrupt, although symptoms can still occur and may sometimes be delayed. Fluoxetine may therefore be reduced more quickly than some shorter-acting antidepressants in certain circumstances, but it should still be stopped according to an agreed plan. Its long duration of action also explains why a washout of several weeks may be required before starting medicines that must not overlap with it, particularly MAOIs.
What to expect during a switch
Every antidepressant switch is different, but symptoms often follow a broad timetable. Understanding the usual pattern can make it easier to interpret what you are experiencing and recognise when to contact your prescriber.
The first few days
During a direct switch or cross-taper, withdrawal symptoms from the first antidepressant may appear within a few days of reducing or stopping it. Early side effects from the new medication may begin at the same time, which can make the two difficult to distinguish.
Common withdrawal symptoms include:
- Dizziness, light-headedness or feeling unsteady
- Brief electric-shock sensations, often called “brain zaps”, in the head or body
- Nausea
- Irritability, tearfulness or increased emotional sensitivity
- Vivid or unpleasant dreams
- Aching, chills or flu-like symptoms
For many people, these symptoms are mild and resolve within several days or one to two weeks. For others, they can be more intense or persist for longer. NICE recognises that withdrawal can occasionally be severe or continue for several weeks or months.
Withdrawal symptoms do not predict whether the new antidepressant will be effective. However, severe or difficult symptoms may indicate that the switching plan needs to be reviewed.
A 2024 systematic review and meta-analysis estimated that approximately 15 per cent of people experience withdrawal symptoms attributable to stopping the antidepressant, after accounting for symptoms also reported by people stopping a placebo. Severe symptoms occurred in approximately 2.8 per cent. These are population estimates drawn from varied studies, so they cannot predict an individual person’s experience.
Weeks one to three
During the first few weeks, the new antidepressant may not yet be producing a clear benefit. Early side effects can be more noticeable than improvements, and sleep, appetite or energy may shift before mood does. Some people notice very little at this stage.
A lack of early improvement does not necessarily mean that the switch will be unsuccessful. The timing depends partly on the medication, the starting dose and how quickly an appropriate treatment dose is reached.
Weeks three to six
By this stage, it may be possible to assess whether the new antidepressant is beginning to help. NICE recommends reviewing treatment within two to four weeks and advises that, if an antidepressant is going to be effective, some benefit is usually apparent within four weeks. Improvement may continue to develop after this point.
If there has been little or no improvement by around six weeks, tell your prescriber. This does not necessarily mean that the medication is unsuitable, but it provides important information for deciding whether the dose, switching plan or wider treatment approach should be reviewed.
Distinguishing withdrawal from returning depression or anxiety
Withdrawal and the return of the original condition can feel similar, and it is not always possible to separate them clearly. Some features may offer useful clues:
- Timing: Withdrawal often begins within days of a dose reduction or stopping a medication. Returning depression or anxiety usually develops over weeks or months. With longer-acting medicines such as fluoxetine, withdrawal symptoms may be delayed.
- Type of symptoms: Withdrawal is more likely to include unfamiliar physical sensations such as dizziness, nausea or brain zaps. A return of depression or anxiety may feel more like the symptoms experienced before treatment.
- Response to reinstating the previous dose: Withdrawal symptoms may improve within hours or days if the earlier dose is reinstated under medical guidance. Symptoms caused by returning depression or anxiety usually take longer to respond.
These are useful indicators, not a test to perform on yourself. Withdrawal and returning symptoms can overlap or occur together. If you are unsure what you are experiencing, contact your prescriber rather than adjusting the dose or waiting for the symptoms to resolve without support.
Download on the App Store Claro helps you track sleep, side effects, mood, and daily functioning between visits — so you walk into your next appointment with a clear picture, not a blank mind.
Common antidepressant switches and what to expect
The examples below describe general switching approaches. The exact schedule and starting dose will depend on the medicines involved, your current dose, previous withdrawal symptoms and your individual circumstances.
Sertraline to escitalopram
Sertraline and escitalopram are both SSRIs and act in broadly similar ways. Therefore, a direct switch is normally possible. This means stopping sertraline and starting escitalopram the following day. A planned overlap is not usually required and should only be used if specifically prescribed.
Sertraline has an average half-life of approximately 26 hours, so its level falls substantially during the days after the final dose. If withdrawal symptoms occur, they may begin during this period.
For the treatment of depression, 10 mg once daily is the usual licensed adult dose of escitalopram. However, a prescriber may choose a lower starting dose depending on factors such as age, side effects, other health conditions and the reason for switching.
Fluoxetine to another antidepressant
Fluoxetine requires a different approach because it and its active metabolite remain in the body for much longer than most other antidepressants. As a result, fluoxetine can continue to interact with other medicines for several weeks after the final dose.
When switching to another SSRI, an SNRI or most tricyclic antidepressants, guidance generally recommends reducing fluoxetine to 20 mg, stopping it and waiting four to seven days before starting the new medicine at a low dose. There are important exceptions. Switching to clomipramine usually requires a wait of 14 to 21 days, while an MAOI requires a washout of five to six weeks and specialist supervision.
Fluoxetine’s prolonged action can make withdrawal less abrupt for some people, but it should not be regarded as automatically tapering itself. Withdrawal symptoms can still occur and may be delayed. The switching plan should therefore be based on the specific destination medicine rather than a single standard waiting period.
An SSRI to an SNRI, such as sertraline to venlafaxine
SSRIs act mainly on serotonin, while SNRIs affect both serotonin and noradrenaline. For most SSRIs other than fluoxetine, a direct switch to an SNRI is normally possible. The first SSRI is stopped and the SNRI is started the following day at a dose selected by the prescriber.
During the first few days, side effects such as nausea, dizziness, sweating, sleep disturbance, nervousness or increased anxiety may occur. These effects often improve as the body adjusts, but persistent or severe symptoms should be discussed with the prescriber.
Venlafaxine is associated with a relatively high risk of withdrawal symptoms if doses are missed or the medicine is later reduced too quickly. This does not necessarily mean that sertraline must be tapered before a direct switch. It means that venlafaxine should be taken consistently and gradually reduced if it is eventually stopped.
Additional caution is required when switching from paroxetine. Paroxetine inhibits the liver enzyme CYP2D6, which helps metabolise venlafaxine and duloxetine. This can temporarily increase levels of the new medicine and the likelihood of side effects. The prescriber may take this into account when selecting the starting dose and monitoring the switch.
What to ask at your appointment
An antidepressant switch is easier to manage when the plan is clear from the outset. Before leaving your appointment, consider asking:
- Which switching method are we using, and what is the schedule for each medicine?
- When should I reduce or stop the first antidepressant?
- What dose of the new antidepressant will I start with, and when might it be increased?
- Which symptoms are expected during the first week, and which should prompt me to seek medical advice?
- What should I do if I miss a dose or take one at the wrong time?
- When will the switch be reviewed?
- Who should I contact if I have difficulties before the next appointment, and how quickly can I expect a response?
- Are there any prescription medicines, over-the-counter products, supplements or herbal remedies that I should avoid?
The final question is particularly important. Products such as St John’s wort, the painkiller tramadol, some migraine medicines called triptans and the antibiotic linezolid can interact with certain antidepressants. The risk depends on the specific combination, so do not stop another prescribed medicine without advice.
Make sure your prescriber and pharmacist know everything you take, including occasional medicines and supplements.
When to seek help
Many symptoms experienced during an antidepressant switch are temporary and manageable but others require prompt medical assessment. Before starting the switch, make sure you know whom to contact during working hours and where to seek help outside them.
Contact your prescriber or GP promptly if:
- Your mood or anxiety becomes noticeably worse
- Withdrawal symptoms are intensifying, difficult to manage or not beginning to settle
- Side effects are interfering with work, sleep or everyday responsibilities
- You develop pronounced restlessness, agitation, anxiety or unsteadiness
- You are unsure whether your symptoms are caused by withdrawal, the new medicine or a return of your original condition
Seek urgent help if:
- You have thoughts of harming yourself or ending your life
- You feel unable to keep yourself or someone else safe
- Agitation or confusion occurs alongside symptoms such as fever, heavy sweating, shivering, a fast heartbeat, diarrhoea, muscle rigidity, twitching or tremor
- You experience fainting, a seizure, chest pain, difficulty breathing or severe confusion
Do not wait for a scheduled appointment if symptoms are severe or worsening quickly.
In the UK: If you or someone else is in immediate danger, call 999 or go to A&E. In England, urgent mental health support is available through NHS 111 online or by calling 111 and selecting the mental health option. The NHS also provides links to urgent services in Scotland, Wales and Northern Ireland. For confidential emotional support, call Samaritans free on 116 123 at any time.
In the US: If there is immediate danger, call 911 or go to an emergency department. The 988 Suicide and Crisis Lifeline is available free at any time by phone, text or online chat.
A note on serotonin syndrome
Serotonin syndrome is an uncommon but potentially serious reaction caused by excessive serotonin activity. It is more likely when serotonergic medicines are taken together or too close together during a switch.
Combining an MAOI with an SSRI or SNRI presents a particularly high risk, which is why these switches require a washout period and specialist supervision. Other medicines and supplements can also contribute, including tramadol, some triptan migraine medicines, linezolid and St John’s wort.
Symptoms can range from mild to life-threatening. Warning signs include agitation, confusion, sweating, shivering, diarrhoea, a fast heartbeat, tremor, muscle twitching, rigidity and fever. A single symptom does not necessarily indicate serotonin syndrome, but several occurring together require urgent medical advice, especially if they begin soon after starting a medicine or increasing a dose. NHS guidance recommends monitoring for these symptoms during and after a switch.
Younger adults during the first few weeks
In the UK: The MHRA advises that the risk of suicidal thoughts or behaviour may be increased in people under 25 taking antidepressants, particularly during the early stages of treatment. NHS switching guidance recommends reviewing people aged 18 to 25 within one week of starting the new antidepressant.
In the US: Antidepressants carry an FDA boxed warning about an increased risk of suicidal thoughts and behaviour in children, adolescents and young adults aged 24 or younger during short-term treatment. Close monitoring is advised during the early months of treatment and after dose increases or reductions.
These warnings call for closer monitoring, not automatic avoidance of antidepressants. If you are in this age group, agree in advance what to watch for, when the first review will take place and whom to contact if your mood worsens or your behaviour feels unusual. With your agreement, it may also help for someone you trust to know the plan.
Frequently asked questions
What dose of escitalopram is equivalent to 50 mg of sertraline?
Research-based dose charts generally place 50 mg of sertraline at approximately 10 mg of escitalopram. However, this is an estimate based on average doses used in clinical trials, not a direct conversion. It does not mean that everyone switching from 50 mg of sertraline should start with 10 mg of escitalopram. The prescriber will select a dose based on the reason for switching, previous side effects, withdrawal risk and individual circumstances.
Can antidepressants be switched abruptly?
Some antidepressants can be switched directly, meaning that the first is stopped and the second is started the following day. This is often possible when switching between similar medicines, such as most SSRIs. A supervised direct switch is different from stopping an antidepressant suddenly without a replacement or an agreed plan. Unplanned abrupt withdrawal can cause significant symptoms, particularly after longer-term treatment or with medicines that have a higher withdrawal risk.
How long does an antidepressant switch take?
It depends on the method. A direct switch takes place from one day to the next, while a cross-taper commonly lasts two to four weeks. A washout may add several days or, for some switches involving an MAOI, several weeks. Benefits from the new antidepressant may begin within one or two weeks, but it can take longer to judge the overall response. NHS guidance recommends reviewing the medicine if no benefit is apparent after four to six weeks.
What withdrawal symptoms can occur during a switch?
Common symptoms include dizziness, brain zaps, nausea, irritability, anxiety, disturbed sleep, vivid dreams, headaches and flu-like aches. They often begin within a few days of reducing or stopping the first antidepressant. Longer-acting medicines such as fluoxetine may produce delayed symptoms. NICE advises that withdrawal symptoms often resolve within one to two weeks, although they can sometimes be more severe or persist for longer.
Is a washout needed when switching between SSRIs?
Usually not. For most SSRIs, NHS guidance states that a direct switch is normally possible. Fluoxetine is the main exception because it remains active in the body for much longer. NHS guidance generally recommends reducing fluoxetine to 20 mg, stopping it and waiting four to seven days before starting another SSRI at a low dose. The precise interval should be selected by the prescriber. Longer washout periods are required when switching to or from an MAOI.
Will the new antidepressant cause start-up side effects?
It may. Even when switching between antidepressants in the same class, the new medicine can cause effects such as nausea, headaches, sleep disturbance, dizziness or increased anxiety. These often improve during the first few weeks, although experiences vary. During a cross-taper, start-up effects from the new antidepressant may occur alongside withdrawal symptoms from the first, making them difficult to distinguish. Contact your prescriber if symptoms are severe, worsening or difficult to manage.
Sources
- NHS Specialist Pharmacy Service. Switching strategies for antidepressants, SSRIs to other antidepressants: switching in adults, MAOI to other antidepressants: switching in adults, Planning and agreeing an antidepressant switching strategy, Considerations when choosing an alternative antidepressant, Monitoring a person during and after antidepressant switching.
- National Institute for Health and Care Excellence. NG222: Depression in adults: treatment and management, NG215: Medicines associated with dependence or withdrawal symptoms: safe prescribing and withdrawal management for adults.
- Joint Formulary Committee. British National Formulary. Antidepressant monographs and adult dose ranges. BMJ Group and Pharmaceutical Press.
- Medicines and Healthcare products Regulatory Agency. Selective serotonin reuptake inhibitors and serotonin and noradrenaline reuptake inhibitors: use and safety.
- Royal College of Psychiatrists. Stopping antidepressants.
- Hayasaka Y, Purgato M, Magni LR, et al. Dose equivalents of antidepressants: evidence-based recommendations from randomized controlled trials. Journal of Affective Disorders. 2015;180:179 to 184. doi:10.1016/j.jad.2015.03.021.
- Trivedi MH, Rush AJ, Wisniewski SR, et al. Evaluation of outcomes with citalopram for depression using measurement-based care in STAR*D: implications for clinical practice. American Journal of Psychiatry. 2006;163(1):28 to 40. doi:10.1176/appi.ajp.163.1.28.
- Henssler J, Schmidt Y, Schmidt U, et al. Incidence of antidepressant discontinuation symptoms: a systematic review and meta-analysis. The Lancet Psychiatry. 2024;11(7):526 to 535. doi:10.1016/S2215-0366(24)00133-0.
- National Institute of Mental Health. Questions and answers about the STAR*D Level 1 results.
Claro articles are for self-monitoring and educational purposes only. They are not a medical device, therapist, or diagnostic tool, and do not replace care from your prescribing clinician. If you are in crisis, contact your care team, emergency services, the Samaritans (UK: 116 123), or the Crisis Text Line (US: text HOME to 741741).