Researchers from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King”s College London have conducted a comprehensive study analyzing the side effects of various antidepressants, particularly focusing on their impact during the initial eight weeks of treatment. This investigation, which involved data from over 58,000 participants across more than 150 studies, was published in The Lancet.
The study highlights significant variations in weight change, heart rate, and blood pressure associated with different antidepressants. Researchers aim to inform and empower patients, encouraging them to consult healthcare professionals regarding any concerns they may have.
In the 2024/25 period, approximately 92.6 million antidepressants were prescribed to around 8.89 million patients in England, according to data from the NHS Business Services Authority (NHSBSA). Notably, the antidepressant sertraline, prescribed to about 2.9 million patients last year, was associated with an average weight loss of 0.76 kg and a decrease in heart rate by about two beats per minute, although it did show slight increases in both systolic and diastolic blood pressure.
Another commonly prescribed antidepressant, amitriptyline, which was given to 2.2 million patients in the same period, revealed a contrasting trend. This tricyclic antidepressant was linked to an average weight increase of 1.6 kg along with a heart rate increase of nine beats per minute, and rises in both systolic and diastolic blood pressure. Despite its efficacy, amitriptyline is not typically recommended as a first-line treatment for depression, as the National Institute for Health and Care Excellence advises that selective serotonin reuptake inhibitors (SSRIs) like sertraline be tried first.
Citalopram, another SSRI prescribed to about 1.4 million patients, was found to be associated with an average weight loss of 0.65 kg and reductions in heart rate and systolic blood pressure, but a minor increase in diastolic blood pressure.
The research team noted an approximate four-kilogram difference in weight changes depending on the prescribed medication, with agomelatine users losing an average of 2.44 kg, while maprotiline, which is less commonly prescribed in the UK, was associated with an average weight gain of 1.82 kg. The study also identified a notable over 21 beats-per-minute difference in heart rate changes between fluvoxamine, which decreased heart rate by eight beats per minute, and nortriptyline, which increased it by an average of 13.8 beats per minute.
Dr. Toby Pillinger, the study”s senior author, emphasized the importance of recognizing that antidepressants are not all the same, as some can lead to significant changes in physical health within a short time frame. He stated, “The aim isn”t to deter use, but to empower patients and clinicians to make informed choices and to encourage personalized care.”
Study co-author Andrea Cipriani, a professor at the University of Oxford, underscored the necessity of shared decision-making in clinical settings, particularly in mental health, to ensure treatment aligns with patient preferences and values.
Rosie Weatherly, from the mental health charity Mind, reiterated the importance of considering individual needs in treatment plans, urging patients to consult their healthcare providers regarding any concerns about side effects.
Professor Azeem Majeed, from Imperial College London, called for routine physical health checks for patients on antidepressants, highlighting the value of awareness regarding potential side effects in facilitating shared decision-making.
Dr. Lade Smith, president of the Royal College of Psychiatrists, welcomed the study”s findings, recognizing the role of antidepressants in treating severe depression and their effectiveness when combined with talking therapies.
Professor Kamila Hawthorne, chair of the Royal College of GPs, confirmed that GPs prescribe antidepressants only with valid reasons and conduct follow-up checks to monitor side effects, emphasizing the importance of regular medication reviews.
