LONDON (FN) — A landmark study has ranked the physical side effects of commonly prescribed antidepressants, revealing significant differences in how the drugs affect patients’ weight, heart rate and blood pressure.
Researchers from King’s College London and the University of Oxford analyzed 151 clinical trials involving more than 58,000 patients and 30 antidepressants. The findings, published in The Lancet, show that some medications can cause weight changes of up to 4 kilograms (8.8 pounds), heart rate fluctuations of 21 beats per minute, and notable shifts in blood pressure within just eight weeks of treatment.
“There are big differences between antidepressants, and this is important not just for individual patients, but for the population at large,” said Professor Oliver Howes of King’s College London. “Even modest changes can have a significant impact when millions are affected.”
Approximately 8 million people in the United Kingdom take antidepressants, and up to 20% of adults in Europe and North America are prescribed them for various mental health conditions.
The study found that agomelatine was associated with an average weight loss of 2.4 kilograms, while maprotiline led to a gain of nearly 2 kilograms. Fluvoxamine slowed heart rate, while nortriptyline increased it by 21 beats per minute. Nortriptyline also raised blood pressure by 11 mmHg compared to doxepin.
“Clearly no two antidepressants are built the same,” said Dr. Atheeshaan Arumuham, a co-author of the study. “These differences can become clinically significant, especially for patients with underlying health conditions.”
Dr. Toby Pillinger, another researcher, emphasized that the findings should not alarm patients but rather empower them to engage in shared decision-making with their healthcare providers. “We’re seeing large changes in physical health parameters even within eight weeks,” he said. “This has clinical relevance.”
The study suggests that treatment should be tailored to individual needs. For example, patients concerned about weight gain may benefit from agomelatine or sertraline, while those with high blood pressure might avoid nortriptyline or venlafaxine in favor of citalopram or paroxetine. Patients with elevated cholesterol could steer clear of duloxetine and opt for more neutral options like escitalopram.
Despite the differences, researchers cautioned against labeling any drug as universally “good” or “bad.” Amitriptyline, for instance, may raise weight and blood pressure but is also effective for pain and sleep issues.
Selective serotonin reuptake inhibitors (SSRIs) — including paroxetine, citalopram, escitalopram and sertraline — were generally associated with fewer physical side effects. Fluoxetine, also known as Prozac, was linked to weight loss and increased blood pressure.
Professor Andrea Cipriani of Oxford noted that 85% of antidepressant prescriptions in the UK are for just three SSRIs: citalopram, sertraline and fluoxetine. He said the findings could lead to more personalized treatments and a reduction in reliance on generic medications.
The research team is developing a free online tool to help clinicians and patients choose the most suitable antidepressant. However, implementing such changes would require a cultural shift within the National Health Service.
Dr. Prasad Nishtala of the University of Bath, who was not involved in the study, called the findings “novel and valuable,” especially for patients on long-term treatment. “The cumulative risks are likely to be higher among those with chronic depression,” he said.
