New UK research has found that different antidepressants can have significantly different physical side-effects, including changes in weight, heart rate, and blood pressure.
The study — led by King’s College London and the University of Oxford — analysed data from 151 clinical trials involving over 58,000 people taking 30 different antidepressants. It revealed that while some drugs caused substantial weight gain, others led to weight loss or had little effect at all.
For example, patients taking maprotiline gained about 2kg on average within two months, while those on agomelatine lost roughly 2.5kg. Nearly half of people prescribed maprotiline or amitriptyline experienced weight gain, compared with over half losing weight on agomelatine.
Researchers also found an average heart rate difference of 21 beats per minute between patients on fluvoxamine and nortriptyline, and an 11 mmHg difference in blood pressure between nortriptyline and doxepin.
Dr Toby Pillinger of King’s College London said the findings highlight that “antidepressants are not identical” and that some can cause “meaningful physical changes” even in a short period. He stressed the importance of personalised treatment and monitoring, especially for drugs with stronger physical effects.
Professor Andrea Cipriani of Oxford added that the results underline the need for shared decision-making between doctors and patients to ensure treatment choices align with individual needs and preferences.
Researchers are now urging updates to antidepressant prescribing guidelines to better reflect these differences.
