Antidepressant washout period A washout period is the gap between stopping one antidepressant and starting another, so the first drug can leave your body before the second begins. It is needed mainly when one of the two is an MAOI, and when switching from fluoxetine, which stays in the body for weeks. The gap prevents dangerous interactions such as serotonin syndrome, but it can bring on withdrawal symptoms from the first medication.
Also called: Washout period, Washout, Drug-free interval.
Written by Alena Kozlova, PhD , from published studies and prescribing information.
Definition medically reviewed by Dr. Jason Tan , Consultant Psychiatrist, on October 28, 2026, this definition only. Next review: October 28, 2027.
What is a drug washout period? A drug washout period is a stretch of days or weeks when you take neither medication, so the first one can clear before the second starts. Your prescriber sets its length from the first medication’s half-life, the time for its level in the blood to fall by half: a drug takes about five half-lives to clear. A drug with a half-life of about a day clears in about five days. Fluoxetine takes weeks, because it and norfluoxetine, the active substance it turns into, last a long time.
What is the washout period for SSRIs? Between most SSRIs no washout is needed; the strict gap, usually 14 days, is between an SSRI and an MAOI, in both directions. MAOIs are an older group of antidepressants, and taking one close to most other antidepressants can cause serotonin syndrome, a dangerous excess of serotonin. The Lexapro prescribing information, for example, requires at least 14 days after stopping an MAOI before starting Lexapro, and at least 14 days after stopping Lexapro before starting an MAOI. After fluoxetine, the gap before an MAOI is at least 5 weeks.
The 14 days are longer than the drugs take to leave the blood, for two reasons. Older MAOIs such as phenelzine and tranylcypromine block their enzyme irreversibly, so their effect outlasts the drug itself, and a 2016 review in Australian Prescriber calls a washout of two to three weeks after them mandatory. In the other direction, 14 days after Lexapro is twice the five half-lives it takes to clear, which leaves a margin.
What people on Reddit say
Few of the people who said how they switched left a gap with neither medication. Of 1,185 people who described coming off an SSRI or SNRI on Reddit, 81 said they switched to another antidepressant. Of the 33 who said how, 25 overlapped the two; only a few left a gap of days or weeks (4) or switched straight away (4). These posts are not a guide to switches that involve an MAOI, where the gap is required. People who write about switching may not be typical, so this shows how it happens, not how often.
From public Reddit posts, counted by withClaro. These are self-reports, not a clinical study.
Can withdrawal happen during a washout? Yes. During the gap you take neither medication, so withdrawal from the first one can start, especially if it has a short half-life. The illness itself can also return while you are on nothing, which a 2016 review in Australian Prescriber names as the main risk of this kind of switch, and the two are hard to tell apart on your own. This is one reason prescribers use a washout only when the combination requires it, and lower the first medication gradually before the gap begins.
Half-life by antidepressant Half-lives of five common antidepressants, shortest first.
Half-lives of all antidepressants
How long does it take for an SSRI to be out of your system? For most SSRIs, a few days to about a week: five half-lives of about a day for sertraline, and a little longer for escitalopram, at 27 to 32 hours, and citalopram, at about 33 to 35, by their US prescribing information. This is how long the drug takes to leave the blood; it does not shorten the gap required before or after an MAOI, described above. The table above gives the half-lives of five common antidepressants.
What to do If your switch needs a washout, ask your prescriber how long it will be, how the first medication will be lowered before it, and what to do if withdrawal symptoms or your old symptoms start during the gap. If your mood drops sharply or you have thoughts of harming yourself, contact them now; for thoughts of self-harm, call or text 988 in the US or your local emergency number. After the second medication starts, several signs of serotonin syndrome together, such as sweating, shivering, twitching muscles and a racing heart, are a reason to call your prescriber the same day. A high fever, rigid muscles, confusion or a seizure need emergency care: in the US, call 911 or go to the nearest emergency room; elsewhere, call your local emergency number.
Read how switching antidepressants works
How withClaro helps A quick check-in on mood, sleep and energy while you’re between medications A chart that shows early if things start to slip Get the withClaro app on the App Store
Related terms Sources U.S. Food and Drug Administration. Lexapro (escitalopram) tablets and oral solution: prescribing information. FDA / DailyMed, 2026. U.S. Food and Drug Administration. Prozac (fluoxetine): prescribing information. FDA / DailyMed, 2026. U.S. Food and Drug Administration. Zoloft (sertraline) tablets and oral solution: prescribing information. FDA / DailyMed, 2025. U.S. Food and Drug Administration. Celexa (citalopram): prescribing information. FDA / DailyMed, 2023. Keks N, Hope J, Keogh S. Switching and stopping antidepressants. Australian Prescriber, 2016. Gury C, Cousin F. Pharmacokinetics of SSRI antidepressants: half-life and clinical applicability. L'Encéphale, 1999. Horowitz MA, Taylor D. The Maudsley Deprescribing Guidelines. Wiley, 2024. All glossary terms