Alamy Stock Photo / Daria Kulkova
Patients taking antidepressants are being urged to talk to their prescribers before stopping their medications, after a study published in The Lancet showed “strong evidence” that the drugs can cause clinically relevant changes in body weight, heart rate and blood pressure within a few weeks.
Researchers from the Institute of Psychiatry, Psychology and Neuroscience (IoPPN) at King’s College London — in collaboration with the University of Oxford’s Department of Psychiatry — analysed data from 151 different studies and compared the physical health effects of 30 different antidepressants across more than 58,000 people after around eight weeks of antidepressant use.
In patients taking agomelatine and maprotiline, there was up to a 4kg difference in average weight change between the drugs, which is equivalent to around 2kg of weight loss with agomelatine compared with 2kg of weight gain with maprotiline, the results showed.
The researchers also estimated that weight gain occurred in nearly half (48%) of the patients prescribed some antidepressants, such as maprotiline or amitriptyline, while more than half (55%) of patients who were given agomelatine experienced weight loss.
There was also a 21-beat-per-minute difference in heart rate between patients prescribed fluvoxamine compared with nortriptyline, the study found.
By contrast, some commonly prescribed serotonin selective re-uptake inhibitors (SSRIs) — the most commonly used type of antidepressant — showed little or no adverse impact on these physical health measures.
Based on their findings, researchers are calling for antidepressant treatment guidelines to be updated.
However, senior study author Toby Pillinger, an academic clinical lecturer at the IoPPN and consultant psychiatrist at the South London and Maudsley NHS Foundation Trust, said: “The aim [of the study] isn’t to deter use but to empower patients and clinicians to make informed choices and to encourage personalised care.
“Antidepressants are among the most widely used medicines in the world.”
“While many people benefit from them, these drugs are not identical — some can lead to meaningful changes in weight, heart rate and blood pressure in a relatively short period. Our findings show that SSRIs, which are the most prescribed type of antidepressant, tend to have fewer physical side effects, which is reassuring. But for others, closer physical health monitoring may be warranted,” he added.
Ewan Maule, clinical director at North East and North Cumbria NHS, commented: “This latest research gives some useful information to inform a decision but it is not the full picture.
“Anybody wanting to discuss the best medicine for themselves needs to have an individual discussion with a healthcare professional. For most people, these medicines are effective and life-stabilising — but like any long-term treatment, they need regular review and a safe plan for stopping.”
“It’s really important that people don’t stop antidepressants suddenly. Stopping them abruptly can cause severe withdrawal symptoms — not just feeling low, but dizziness, agitation, electric-shock sensations, and in some cases, serious relapse of depression or anxiety,” he added.
“Anyone asking about discontinuing or switching should arrange (non urgently) to speak to the pharmacist or GP who is looking after their repeat prescribing. Whilst patients prescribed antidepressants should already be having regular discussions with their prescriber and should have a plan for how long to stay on them, they may need help arranging a structured medication review to go through their options.”
Co-author David Taylor, director of pharmacy and pathology at South London and Maudsley NHS Foundation Trust, told The Pharmaceutical Journal that the study is “aimed at helping distinguish between antidepressants” by “comparing them in terms of their relative risk of individual adverse effects”.
Noting that “antidepressant prescribing continues to grow and the number of people taking antidepressants is at an all-time high”, Taylor added that he would be “surprised if there was any fall-out” from the study in terms of patients asking advice about wanting to stop their antidepressant medicines.
“The paper is meant to compare adverse effect risk, not to emphasise the fact that adverse effects occur. The paper combines data from different sources to compare risks [which] have been acknowledged for some time,” he said.
In May 2025, results of a study showed that antidepressants — particularly SSRIs — are associated with a “statistically substantial increased risk” of postural hypotension in older people during the first 28 days of use.
