Antidepressants could be putting millions of patients at increased risk of weight gain, hypertension and heart problems a major review has today revealed, prompting doctors to reconsider prescription practices and monitor patients more closely.
British neuroscientists who reviewed data from over 58,500 participants, comparing 30 different antidepressants, found the drugs differ significantly in their physiological effects, particularly with regards to cardiovascular health.
In particular, they found that amitriptyline—a tricyclic antidepressant used to treat low mood and depression—causes weight gain in almost half of patients prescribed them, increased heart rate and heightened blood pressure, significantly increasing the risk of heart disease and even death.
In the general population it’s estimated that for every 1kg increase in body weight, cardiovascular risk increases by around 3 per cent.
According to the study’s findings, patients prescribed amitriptyline put on 1.5kg after just eight weeks of being on the drug.
Furthermore, their heart rate increased by 9bmp, and their systolic blood pressure—the pressure in your arteries when the blood is pumped by the heart—rose by 5mmHg, increasing the risk of stroke by 5 per cent and risk of all-cause death by nearly 10 per cent.
Patients who prescribed nortriptyline—which again works by boosting levels of serotonin in the brain—increased heart rate by over 13 beats per minute.
Writing in The Lancet, the researchers concluded guidelines should be updated to reflect differences in physiological risks, and choice of antidepressant should be made on an individual basis—taking into consideration patient history.
NHSBSA data show that amitriptyline was given to 2.2 million patients in England in 2024/25
Other antidepressants that were found to significantly increase weight gain included mirtazapine and several other tricyclic antidepressants, which work by stimulating serotonin receptors in the brain.
Overall, the researchers, led by academics at King’s College London, identified a 4kg difference in weight change depending on which drug a patient was prescribed.
The team also found strong evidence of increases in blood pressure with serotonin-noradrenaline reuptake inhibitors (SNRIS) like duloxetine—which are thought to work by increasing levels of serotonin and noradrenaline, in the brain—and amitriptyline.
Dr Toby Pillinger, a consultant psychiatrist and study senior author, said: ‘Antidepressants are among the most widely used medicines in the world.
‘While many people benefit from them, these drugs are not identical—some can lead to meaningful changes in weight, heart rate and blood pressure in a relatively short period.
‘Our findings show that SSRIs, which are the most prescribed type of antidepressant, tend to have fewer physical side-effects, which is reassuring.
‘But for others, closer physical health monitoring may be warranted.’
The researchers found that patients on citalopram, a commonly prescribed SSRI, dropped around 0.65kg in weight and saw decreases to heart rate and systolic blood pressure, but a slight increase in diastolic blood pressure—the pressure in your arteries between heartbeats.
It comes as figures show an estimated 8.8 million people in England take antidepressants, about one in seven people, with numbers increasingly annually.
In 2024-25 alone, over 92 million antidepressants were prescribed.
Responding to the landmark review, world leading psychiatrists labelled the findings ‘important’, adding that the results ‘underscore the need for routine physical health checks in those treated with antidepressants’.
Dr Prada Nishtala, an expert in pharmacoepidemiology at the University of Bath, said: ‘The average treatment duration in the included trials was around wight weeks, yet in real-world settings, where patients often receive antidepressants for months or years, the cumulative risks are likely to be higher, particularly among those with chronic depression or existing metabolic conditions.’
She added that the findings add to surmounting evidence that antidepressants should be incorporated into the UK’s existing QRISK assessment, used to estimate patients’ 10- year risk of heart attack or stroke.
‘Such an update would better reflect the true metabolic burden of psychiatric pharmacotherapy and support safer more personalised prescribing.’
Study co-author, Professor Andrea Cipriani from the University of Oxford, echoed her concerns stating: ‘Most clinical decisions—especially in mental health—are still made by physicians with little input from patients.
‘Our results emphasise the importance of shared decision making, the collaborative process through which patients are supported by the clinicians to reach a decision about their treatment, bringing together their preferences, personal circumstances, goals, values and beliefs.
‘This should be the way forward in the NHS and globally.’
Researchers compared 30 different antidepressants with a placebo and found a 4kg difference in weight change, over 21 bmp difference in heart rate change and over 11mmHg difference in blood pressure on certain medications
But other experts are more cautious, urging people on antidepressants not to stop taking their medication without taking to the medical professional responsible for their care about their concerns first.
‘These findings do not show major new physical side effects of antidepressants, and so should not be a cause for concern,’ Professor Frank Moriarty, an expert in biomolecular sciences at RSCO University of Medicine and Health Sciences said.
‘It’s also important to bear in mind that this study only looked at physical side effects of these medicines. It does not provide any evidence on their possible benefits, nor on other possible harms, including the effects when a patient stops taking these medicines.’
The researchers concluded: ‘The aim isn’t to deter use, but to empower patients and clinicians to make informed choices and to encourage personalised care.’
Uptake of antidepressants has soared in recent years, despite growing unease among experts about the effectiveness of the drugs in actually treating depression.
Previous studies have linked their use to health issues including heart problems in young people alongside long-term and even permanent sexual dysfunction.
But, Dr Alison Cave, chief safety officer at the Medicines and Healthcare products Regulatory Agency (MHRA), wants to reassure patients: ‘All known side effects are clearly outlined in the product information leaflet the comes with medicines, which contains important details on how to take the medicine safely and what side effects to look out for.’
Those who are concerned about the side effects of antidepressants are advised to talk to a healthcare professional before stopping their medication.
Clinicians can sometimes offer an alternative dose, a different drug, or prescribe another medication to combat the side effects.
They urge patients who are taking them not to quit without talking to the medical professional responsible for their care first to ensure they are adequately supported.
She added: ‘Anyone who has questions or experiences symptoms while taking antidepressants should speak to a healthcare professional and report suspected side effects via the Yellow Card scheme.’
