The serotonin myth is over. That is not an argument against antidepressants.

A viral post says people were misled for decades about serotonin and antidepressants. Most of that is right. The conclusion readers draw from it does not follow, and that is the part that can hurt someone.

A post doing the rounds on Facebook quotes the psychiatrist Joanna Moncrieff, and the argument runs roughly like this: people have been misled for three decades about what causes depression, the serotonin theory has no solid evidence behind it, and antidepressants are foreign chemicals we know little about.

The first two parts are largely right. The conclusion most readers draw from them does not follow, and drawing it can be dangerous.

What is actually true

In 2022, Moncrieff and colleagues published an umbrella review in Molecular Psychiatry pulling together six separate lines of serotonin research: serotonin and its metabolite in body fluids, receptor studies, transporter studies, tryptophan depletion experiments, the serotonin transporter gene, and gene by stress interactions.

Their conclusion: there is no consistent evidence that depression is caused by low serotonin activity.

That was not really news inside the field. The simple "depression is a chemical imbalance" story had been out of favor in academic psychiatry for years before the public heard about it. What Moncrieff documents in her 2025 book is how the story survived anyway, because it was useful to the people selling the drugs and reassuring to the people taking them.

So the chemical imbalance explanation you were probably given is not supported. That part is fair.

What the review does not show

Here is where the Facebook version goes wrong.

The review is contested. A group including Sameer Jauhar and Philip Cowen published a detailed riposte arguing that it summarised other people's reviews rather than analyzing data, included studies selectively, and misread parts of the imaging and pharmacology literature. You do not have to pick a side to notice this is an active argument rather than a settled verdict.

More importantly, whether a drug works and why it works are different questions, answered by different kinds of study.

Knowing the mechanism is not what tells you a treatment works. Trials tell you that. Aspirin was in use for roughly seventy years before anyone worked out what it does to prostaglandins, and it relieved pain the entire time. Lithium's mechanism is still not settled. General anaesthesia is given millions of times a year on an explanation that remains genuinely murky.

So "the serotonin story was wrong" does not lead to "the pills do nothing". It leads to "we do not know why they help".

What the trials say

The largest analysis is Cipriani and colleagues in The Lancet, 2018: 522 trials, 116,477 patients, 21 drugs. All 21 beat placebo.

Two honest caveats, and both matter.

The average effect is modest. The standardised difference against placebo is about 0.3, which is real but not transformative, and it averages people who responded very well with people who got nothing.

And the advantage is clearest in severe depression. For mild depression the gap narrows to the point where the trade against side effects is genuinely arguable, which is why guidelines in several countries put therapy first in mild cases.

That is a less dramatic picture than either camp offers. Antidepressants are a moderately effective treatment with an uncertain mechanism. Not a miracle, and not a fraud.

The part of Moncrieff's case that deserves more credit

Withdrawal.

For years the standard line was that coming off antidepressants caused brief, mild "discontinuation symptoms". Moncrieff and Mark Horowitz were among those who pushed back, and the field has moved towards them. Withdrawal can be prolonged and severe for some people, tapering usually needs to be far slower than the old advice suggested, and patients who reported this were often not believed.

Had the Facebook post led with that, it would have been standing on firmer ground than the serotonin argument.

The inference that can hurt you

The dangerous move is going from "the explanation I was given was wrong" to "I should stop taking this".

The ANTLER trial, published in the New England Journal of Medicine in 2021, followed 478 primary care patients who had had at least two episodes of depression, had been on antidepressants for at least nine months, and felt well enough to consider stopping. They were randomly assigned to continue or to taper off.

At 52 weeks, 39% of those who stayed on had relapsed, against 56% of those who came off. Withdrawal symptoms were more common in the discontinuation group. Only about a third of the people asked to stop were still off their medication at the end.

Read that in both directions. Plenty of people did come off successfully, which matters if that is what you want. But stopping raised the chance of relapse substantially, and that was in people who felt well, tapering under supervision, in a trial. That is the best case.

Stopping suddenly, alone, after reading something online, is the same decision with none of the safeguards.

What to do with this

If you are taking antidepressants and they are helping, a wrong explanation does not undo the help. They did not stop working when the serotonin story fell apart.

If you want to come off, that is a legitimate goal, and it is a plan rather than a decision. A slow taper agreed with your prescriber, usually slower than you expect, and ideally not during a crisis or an upheaval.

If you are being offered medication now, it is worth knowing what the guidelines actually say, because it is less drug-first than most people assume. NICE does not recommend antidepressants as the routine first step for less severe depression. Psychological therapy comes first, specifically CBT or behavioral activation. For moderate to severe depression medication is a first-line option, and there combining it with therapy does better than either alone.

So the useful questions are: how severe is this, what are we trying first, what should I expect and by when, and when do we review whether it is still worth taking. We ranked what else actually helps separately.

And if the chemical imbalance line is what made treatment feel acceptable to you, it is worth knowing you never needed it. Something can help without your having a deficiency, and being depressed was never evidence of a broken brain.

This is general information, not medical advice. Never stop or change a prescribed medication without talking to the person who prescribed it.

This article is for general information and is not a substitute for professional care. If you are in crisis or thinking about harming yourself, please contact your local emergency services or a crisis line. See crisis lines.