A large UK study has revealed that different antidepressants can cause markedly different physical side-effects — including weight changes, altered heart rates, and shifts in blood pressure.
Researchers from King’s College London and the University of Oxford analysed data from 151 clinical trials involving over 58,000 people, comparing 30 antidepressants. The results showed weight differences of up to 4kg (nearly 9lbs) between drugs, even within the first two months of use.
Patients taking maprotiline gained an average of 2kg, while those on agomelatine lost about 2.5kg. Nearly half of those on maprotiline or amitriptyline experienced weight gain, while more than half on agomelatine lost weight.
The study also found cardiovascular differences — including a 21-beat-per-minute variation in heart rate between people on fluvoxamine and nortriptyline, and an 11 mmHg blood pressure difference between nortriptyline and doxepin.
Lead author Dr Toby Pillinger said the findings highlight the need for personalised care: “Antidepressants are not identical — some can lead to meaningful changes in weight and heart rate even after a short time. The goal isn’t to discourage use but to help patients and doctors make informed choices.”
Professor Andrea Cipriani of Oxford added that the results underline the importance of shared decision-making, where treatment plans are tailored to each patient’s circumstances and preferences.
Researchers are calling for antidepressant treatment guidelines to be updated to reflect the wide variation in physical side-effects across medications.
