By Antidepressant Side Effects Vary Widely, Landmark Study Finds
A groundbreaking UK study has, for the first time, compared how different antidepressants affect the body — revealing that side effects can vary widely from one medication to another. Researchers found notable differences in weight change, heart rate, and blood pressure among commonly prescribed drugs, raising new questions about how antidepressant treatments should be personalized.
For the first time, scientists have directly compared the side effects of widely used antidepressants — uncovering significant variations that could shape how millions of people are treated for depression.
The research found that within just eight weeks of starting treatment, some antidepressants caused patients to gain or lose weight up to two kilograms, while others influenced heart rate by as much as 21 beats per minute.
In the UK, nearly eight million people take antidepressants. Researchers say the findings could have far-reaching implications for patient safety and treatment adherence.
“There are big differences between antidepressants, and this matters — not only for individuals but for the whole population,” said Professor Oliver Howes, one of the lead authors. “Even modest physical changes can have large-scale health effects when so many people are affected.”
Tailoring Treatment to the Individual
The study, conducted by teams from King’s College London and the University of Oxford, is the first to rate antidepressants by their physical side effects — making it easier for doctors and patients to compare medications.
Published in The Lancet, the research analyzed 151 clinical trials involving more than 58,000 participants and 30 different antidepressants.
While not every patient experienced side effects, the analysis showed clear contrasts between drugs:
- Weight changes: Agomelatine was linked to an average 2.4 kg weight loss, while maprotiline caused a 2 kg gain.
- Heart rate: Fluvoxamine slowed heart rate, while nortriptyline increased it — a 21 beats per minute difference.
- Blood pressure: Doxepin and nortriptyline showed an 11 mmHg variation.
“Clearly, no two antidepressants are built the same,” said Dr. Atheeshaan Arumuham of King’s College London. “Over time, these small differences could add up, increasing the risk of issues like stroke or heart attack.”
A Call for Personalized Prescriptions
Experts say these findings highlight the importance of choosing antidepressants based on each patient’s health needs and preferences.
“Most of the studies we reviewed lasted only eight weeks, yet we saw meaningful shifts in physical health markers,” explained Dr. Toby Pillinger, who spoke to BBC Radio 4’s Today programme. “Our message isn’t to alarm people — it’s to empower them to talk openly with their doctor about the best treatment for them.”
He added that people should not stop taking their medication without consulting a healthcare professional.
Different Patients, Different Needs
The study offered an example of how individual differences shape treatment:
- Sarah (32) wants to avoid weight gain.
- John (44) already has high blood pressure.
- Jane (56) has raised cholesterol.
Although they share the same depression diagnosis, each could benefit from a different antidepressant.
According to Dr. Pillinger, personalized prescribing could make antidepressant treatment safer and more effective for millions.
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