Antidepressants could be putting millions of patients at increased risk of weight gain, hypertension and heart problems, a major review has revealed today, 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 regarding cardiovascular health.
In particular, they discovered that amitriptyline—a tricyclic antidepressant used to treat low mood and depression—causes weight gain in almost half of patients prescribed the drug, increased heart rate and heightened blood pressure, significantly raising the risk of heart disease and even death.
1.5kg Weight Gain in Eight Weeks
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 9 beats per minute, and their systolic blood pressure—the pressure in your arteries when 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.
Nortriptyline Even Worse for Heart Rate
Patients who were prescribed nortriptyline—which again works by boosting levels of serotonin in the brain—experienced heart rate increases of over 13 beats per minute.
The elevated heart rate places additional strain on the cardiovascular system and compounds other risk factors.
Lancet Study Demands Guideline Changes
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.
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.
4kg Difference Between Drugs
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.
This substantial variation demonstrates that not all antidepressants affect patients equally and that prescribing decisions should account for these physical side effects.
Blood Pressure Increases
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.
Elevated blood pressure is a major risk factor for stroke, heart attack and other cardiovascular events.
“Drugs Are Not Identical”
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.
SSRIs Show Better Profile
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.
This more favourable profile for SSRIs provides reassurance that the most commonly prescribed antidepressants pose lower physical health risks.
8.8 Million People in England Take Antidepressants
Figures show an estimated 8.8 million people in England take antidepressants—about one in seven people—with numbers increasing annually.
In 2024-25 alone, over 92 million antidepressants were prescribed.
The scale of antidepressant use means even small increases in cardiovascular risk translate into substantial numbers of people potentially affected.
“Important” Findings
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 eight 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.”
Should Be Added to QRISK Assessment
She added that the findings add to mounting 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.”
Including antidepressant use in cardiovascular risk calculations would ensure doctors account for medication effects when assessing patient health.
“Shared Decision Making” Essential
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 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.
Don’t Stop Without Medical Advice
But other experts are more cautious, urging people on antidepressants not to stop taking their medication without talking 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 RCSO 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.”
“Empower Patients”
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.”
The study seeks to improve prescribing practices rather than discourage antidepressant use altogether.
Soaring Uptake Despite Effectiveness Questions
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.
MHRA Reassurance
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 that 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.
Alternative Options Available
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 antidepressants not to quit without talking to the medical professional responsible for their care first to ensure they are adequately supported.
Yellow Card Scheme
Dr Cave 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.”
The Yellow Card scheme allows patients and healthcare professionals to report suspected side effects to help regulators monitor drug safety.
Implications for Millions
With 8.8 million people in England taking antidepressants, the findings have profound implications for public health.
If even a fraction experience the cardiovascular effects identified in the study, tens of thousands of additional heart attacks, strokes and deaths could occur.
Individual Variation
The study’s revelation of a 4kg weight difference between antidepressants demonstrates that prescribing should be personalised based on patient risk factors.
Someone with existing cardiovascular problems or obesity should perhaps avoid tricyclic antidepressants in favour of SSRIs with better physical health profiles.
Monitoring Essential
The findings underscore the need for regular physical health monitoring of patients on antidepressants, including:
- Weight checks
- Blood pressure measurements
- Heart rate monitoring
- Assessment of cardiovascular risk factors
Long-Term Risks Unknown
Because the study examined eight-week treatment periods whilst many patients take antidepressants for years, the true long-term cardiovascular risks remain unclear.
Cumulative effects over months or years could substantially exceed the risks identified in short-term trials.
Mental Health vs Physical Health
The study highlights the difficult balance between treating mental health conditions and managing physical health risks.
For patients with severe depression, the mental health benefits of antidepressants may outweigh cardiovascular risks—but this calculation should be made explicitly rather than ignored.
As millions of Britons continue taking antidepressants with numbers rising annually, this landmark review demands urgent action to update prescribing guidelines, improve patient monitoring, and ensure shared decision-making that weighs both the mental health benefits and physical health risks of these widely-used medications.
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