New research from King’s College London and the University of Oxford has found that antidepressants can cause markedly different physical side-effects, including changes in weight, heart rate, and blood pressure.
The large-scale review analysed data from 151 clinical trials involving more than 58,000 patients and compared 30 different antidepressants. It revealed that some drugs can cause significant weight gain within weeks, while others can lead to weight loss.
Patients taking maprotiline gained an average of 2kg in the first two months, while those on agomelatine lost about 2.5kg on average — a difference of roughly 4kg between drugs. Nearly half of those taking maprotiline or amitriptyline experienced weight gain, whereas over half on agomelatine lost weight.
The researchers also found notable differences in cardiovascular effects, with a 21-beat-per-minute variation in heart rate between 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 underline the need for personalised treatment. “Antidepressants are widely used and effective, but not identical. Some can lead to meaningful physical changes in a short time,” he said.
He added that SSRIs—the most commonly prescribed type—tend to have fewer physical side-effects, though other antidepressants may require closer monitoring.
Prof Andrea Cipriani of Oxford said the study supports a “shared decision-making” approach, encouraging patients and clinicians to work together to choose the best treatment based on individual preferences and health factors.
Researchers have called for updated clinical guidelines to reflect these differences and improve personalised care in mental health treatment.
