Imagine popping a pill to lift your spirits, only to watch the scale tip up by nearly 5 pounds in just weeks—or worse, face unexpected shifts in your heart rate and blood pressure that could affect your long-term health. That's the startling reality for some people starting antidepressants, according to fresh research.
We're sounding the alarm for anyone currently on sertraline, amitriptyline, citalopram, or maprotiline: a comprehensive study reveals how these common medications can trigger noticeable changes in your body within the first couple of months. As Neil Shaw, our Assistant Editor for Money and Lifestyle, digs into this, let's unpack what the experts are saying and why it matters for your well-being.
This eye-opening review, conducted by a team from the Institute of Psychiatry, Psychology & Neuroscience at King's College London, crunched data from over 58,000 participants across more than 150 studies. They compared 30 different antidepressants against placebos—those inactive pills used in trials—to see how they stack up in terms of side effects during the initial eight weeks of treatment. And the results? Well, it's not just about mood; your physical health could be in the mix too.
But here's where it gets controversial: the study highlights huge variations in how these drugs impact weight, heart rate, and blood pressure, potentially influencing everything from your daily energy to serious health risks. For instance, folks starting certain antidepressants might pack on up to 2 kilograms (that's about 4.5 pounds) in those first two months, while others could actually drop 2.5 kilograms (around 5.5 pounds). It's a stark reminder that not all antidepressants are created equal, and what works for one person might not suit another.
Published in the prestigious journal The Lancet, this work aims to give patients more power in their choices. The researchers emphasize consulting a doctor if you're worried, but they stress that understanding these effects can lead to better outcomes. In the UK, the numbers are staggering: during the 2024/25 period, about 92.6 million antidepressant prescriptions went out to roughly 8.89 million people in England alone. That's according to data from the NHS Business Services Authority.
Take sertraline, also sold as Lustral—it's a go-to for millions. Last year, around 2.9 million English patients were prescribed it. The study links it to an average weight loss of 0.76 kilograms, plus a drop in heart rate by about two beats per minute. However, it might nudge up your systolic and diastolic blood pressure slightly (for beginners, systolic is the top number in your blood pressure reading, showing pressure during heartbeats, while diastolic is the bottom, measuring rest time).
Then there's amitriptyline, handed out to 2.2 million people in England in 2024/25. This one's tied to an average weight gain of 1.6 kilograms, a heart rate increase of nine beats per minute, and rises in both blood pressure readings. Amitriptyline falls into the tricyclic antidepressant category, which doctors don't typically recommend as the first option for depression. Instead, guidelines from the National Institute for Health and Care Excellence suggest starting with selective serotonin reuptake inhibitors (SSRIs)—like sertraline—for their generally milder profiles. Tricyclics are a bit more aggressive on the body, so they're often reserved for specific cases.
Beyond depression, amitriptyline is sometimes used for pain relief or migraines, showing how versatile (and sometimes unexpected) these drugs can be. Another SSRI, citalopram, was prescribed to about 1.4 million people last year. It correlated with an average weight drop of 0.65 kilograms, lower heart rate, and reduced systolic blood pressure, though diastolic might tick up a tad.
And this is the part most people miss: the overall findings show a potential 4-kilogram swing in weight depending on the drug— for example, agomelatine users might lose an average of 2.44 kilograms, while maprotiline (not commonly used in the UK) could lead to a 1.82-kilogram gain. Heart rate differences were even more pronounced, with over a 21-beat-per-minute gap between options like fluvoxamine (which slows the heart by eight beats) and nortriptyline (which speeds it up by 13.8 beats). Why does this matter? Experts note that each kilogram of weight gain bumps up heart disease risk, and blood pressure hikes can raise stroke chances. To clarify, think of it like this: if you're already carrying extra pounds or have high blood pressure, these changes could tip the scales toward bigger issues, like heart strain or complications during exercise.
Of course, the study has limits—it only looks at those early weeks, so we need more research on long-term effects. But Dr. Toby Pillinger, a senior author and academic clinical lecturer at King's Institute, puts it plainly: "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 aim isn’t to deter use, but to empower patients and clinicians to make informed choices and to encourage personalised care."
Andrea Cipriani, a psychiatry professor at the University of Oxford, adds another layer: "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." For newcomers to mental health treatment, shared decision-making simply means doctors and patients teaming up—perhaps discussing your lifestyle, like how active you are or what foods you enjoy, to pick the best fit.
Charities and experts chime in too. Rosie Weatherly from Mind, a mental health charity, urges: "It’s so important that people receive mental health support and treatment that considers their individual needs and preferences. As this study highlights, antidepressants vary in their side effects and health professionals need to carefully consider the benefits and risks of different medications for different people. If you’re already taking medication and you’re worried about its side effects, it’s always OK to ask your doctor or pharmacist for advice. It’s important not to stop taking any medication without advice from a health professional about how to do this safely."
Professor Azeem Majeed from Imperial College London stresses routine check-ups: "For patients and clinicians, the results underscore the need for routine physical health checks in those treated with antidepressants. Moreover, awareness of these side effects is essential to support shared decision-making about the risks and benefits of treatment with antidepressants."
Dr. Lade Smith, president of the Royal College of Psychiatrists, notes: "Antidepressants play a key role in the treatment of more severe depression and are particularly effective when used in combination with talking therapies. As with all drugs, antidepressants have side effects, and we very much welcome this study which helps improve our understanding of some of the physical side effects that can be caused by different types of antidepressants. These findings will help patients and clinicians choose the medication that is best suited to their personal needs."
And Professor Kamila Hawthorne, chair of the Royal College of GPs, reassures that prescriptions aren't handed out lightly: GPs check in two to three weeks post-prescription to spot issues, followed by regular reviews. "These reviews are particularly important, as this study suggests, given that various factors, including lifestyle, can change how an antidepressant works," she says. It's a great example of proactive care—imagine adjusting your diet or adding walks to counteract a drug's effects.
Now, here's a controversial twist: while the study champions patient empowerment, some might argue that highlighting side effects could make people hesitate to start treatment, potentially worsening mental health in a crisis. Is the push for 'informed choices' always empowering, or does it sometimes overwhelm those already struggling?
What do you think? Should antidepressants be chosen more collaboratively, weighing personal risks like weight gain against mental health benefits? Have you switched medications due to side effects, or do you believe lifestyle tweaks can mitigate these changes? Share your thoughts in the comments—we'd love to hear agreements, disagreements, or even your own stories to spark a conversation!
