How millions of patients taking antidepressants may be at risk of a sudden fatal heart event… yet doctors are failing to warn them about it. What EVERY person on the medication needs to know

Rachel Buckmaster was just 27 when she experienced her first heart palpitation.

‘It was a thudding sensation, like someone had hit me in the chest,’ she recalls. ‘I was terrified.’

At first it happened only occasionally, but the episodes became more frequent – and after a month Rachel, a scientist, booked an urgent appointment with her primary care doctor.

‘They fitted me with a 24-hour heart monitor,’ she said. ‘But they couldn’t tell me exactly what was causing it.’

The only advice they could offer was that she stop taking the antidepressant citalopram, which she had been prescribed for post-traumatic stress disorder (PTSD) five years earlier. 

So Rachel came off the drug immediately.

While it took around three months for her mood to stabilize without the medication, the palpitations never returned.

‘The doctors never directly said the antidepressants had caused the heart problem,’ she said. ‘But it was obvious from their advice that they thought the two were connected.

‘I’d never been warned that taking these drugs for years could carry risks like this.

‘For a long time I thought it was just me. Now I know other people have had similar experiences. I just don’t understand why nobody suggested coming off them sooner.’

As worrying as her story is, Rachel, who is from Cambridgeshire in the UK, is far from alone.  

More than 34 million American adults – roughly one in eight – take antidepressants, making them among the most commonly prescribed medications in the US.

The drugs have long been hailed as life-changing treatments for depression and anxiety, helping to relieve symptoms by boosting serotonin – the brain’s ‘feel-good’ chemical.

But what was once more commonly a treatment measured in months is increasingly stretching far beyond that.

Research suggests around half of people prescribed antidepressants have been taking them for more than two years, while millions have remained on the drugs for more than five years.

Many argue that is a good thing. Major depression, which affects about one in 20 adults each year, is a serious illness, and research has found long-term antidepressant use to be a vital tool in reducing the risk of relapse and suicide.

The drugs can also be used to treat sleep disorders, post-traumatic stress disorder (PTSD) and chronic pain.

But the challenge for patients – and for the doctors prescribing these medications – is a stark reality: little is known about the effects of taking antidepressants for years.

Some experts are now warning that the benefits of prolonged antidepressant use are being overstated. More significantly, they point to studies suggesting the drugs may be linked to serious side effects.

Those effects are wide-ranging and include heart problems – including sudden cardiac death – weight gain, weakened bones and fractures, sexual dysfunction, type 2 diabetes, and even dementia and cognitive decline. 

A direct link between these conditions and antidepressants has not been definitively proven. But increasingly, experts believe the emerging evidence is enough to recommend that patients should not remain on the drugs any longer than is medically necessary – and certainly not indefinitely.

One of them is Professor Joanna Moncrieff, a psychiatrist at University College London and a vocal critic of psychiatric medication. She recently took part in a review of research examining the side effects associated with long-term antidepressant use.

The review, which has yet to be published, focused on people taking antidepressants for more than a year and found links to type 2 diabetes, weight gain, and falls and fractures in older adults.

‘We certainly can’t say that long-term antidepressants are safe or harmless,’ Prof Moncrieff says. ‘We have not done enough research to know that. The main finding of our review is that the evidence for the effects of long-term antidepressant treatment is very poor.

‘There are few studies and they are mostly low quality. We haven’t investigated this issue properly, and that should be a cause for concern, especially since there are so many long-term users.

‘Getting into a pattern of using antidepressants for shorter periods than we currently do would reduce the harm they cause and the burden of illness associated with them considerably.’

Psychiatrist Dr Sameer Jauhar, of Imperial College London, adds: ‘We now know from several studies that different antidepressants have different long-term effects – particularly on the heart – and that should be factored into doctors’ prescribing decisions.’

Current clinical guidelines recommend that patients consider stopping antidepressants after at least six months of significant improvement. For people with recurrent depression, treatment may continue for two years or longer.

But few patients are warned about any additional risks of taking antidepressants for years. Partly that’s because the research is difficult to interpret.

People with depression are already at greater risk of heart disease, stroke, type 2 diabetes, obesity and dementia because symptoms such as fatigue and lack of motivation can make it harder to maintain a healthy diet and lifestyle.

Scientists also believe depression itself may contribute to harmful inflammation throughout the body and brain, which is thought to play a role in a range of chronic diseases.

That makes it difficult to determine whether a specific side effect is caused by an antidepressant, or is instead an indirect effect of depression itself.

Professor Glyn Lewis, Professor of Epidemiological Psychiatry at University College London, says many of the studies linking antidepressants to long-term health problems are observational – meaning they follow large groups of people over time. They can identify associations but cannot prove the drugs themselves are responsible. However, he adds: ‘It’s clearly something we have to take seriously.’

Professor of Psychiatry Dr David Healy, who has spent years researching the side effects of antidepressants, believes the potential harms are biologically plausible.

‘Serotonin is in our bones, our joints, our muscles, the peripheral nervous system – lots of places other than our brain,’ he says. ‘If an antidepressant is designed to increase serotonin, it is going to change things throughout the body. The chances are that if you’re on them for a while it could cause problems.

‘Look at other examples, such as antibiotics – they’re fine in the short term, but there’s an increasing chance they become problematic over the long term.’

Some well-established side effects of antidepressants can appear soon after starting the drugs, and patients are generally warned about them. They include emotional blunting, sleep changes, digestive problems and weight gain.

Selective serotonin reuptake inhibitors, or SSRIs – the most commonly prescribed type of antidepressant – can also cause sexual dysfunction and reduced libido.

Other research points to effects on the heart. Older antidepressants known as serotonin-norepinephrine reuptake inhibitors, or SNRIs, and tricyclic antidepressants increase levels of the ‘fight-or-flight’ hormone norepinephrine, which has been linked to an increased heart rate, higher blood pressure, elevated cholesterol and narrowed blood vessels.

Perhaps the most concerning potential effect, however, is that they may prolong the QT interval – a measurement on an electrocardiogram, or ECG, that reflects how long it takes the heart’s lower chambers to contract and reset before the next heartbeat. 

If the QT interval becomes too long, the heart is at risk of a dangerous rhythm disturbance that can cause palpitations, dizziness and – in rare cases – sudden cardiac death.

A 2025 study presented at the European Society of Cardiology Congress found that taking antidepressants for between one and five years was associated with a 56 percent increased risk of sudden cardiac death. Those taking the drugs the longest faced the greatest risk.

 Prof Moncrieff says: ‘We already know these drugs can affect the heart’s electrical activity, so it’s plausible they could have these effects, even though other factors may also be influencing the research.’

The clearest link appears to be with type 2 diabetes, according to Prof Moncrieff’s unpublished analysis. Some of the risk may be explained by the weight gain antidepressants can cause, but researchers also believe the drugs may interfere with the body’s blood sugar regulation.

There is also growing evidence of a higher risk of fractures. Research has suggested that adults over 50 taking SSRIs or tricyclic antidepressants may be up to twice as likely to suffer broken bones, with the risk appearing to rise the longer they remain on the medications.

Exactly why remains unclear. People with depression are more likely to smoke, exercise less and have poorer diets – all of which can weaken bones and increase the risk of fractures.

The evidence linking antidepressants to dementia is far less certain. Depression itself is a major risk factor, making it difficult to separate the effects of the illness from those of the drugs.

But experts say there is a plausible biological explanation for why older antidepressants, particularly amitriptyline, could affect memory. A 2025 Swedish study also suggested people who already had dementia declined more quickly if they were taking high doses of SSRIs.

Prof Moncrieff points to another serious issue with long-term use – that it can make withdrawal symptoms more severe.

These can include ‘brain zaps,’ low mood, anxiety, flu-like symptoms, agitation and insomnia. Patients should never stop taking antidepressants abruptly and should always speak to their doctor about safely coming off the medication, which may involve gradually tapering the dose.

Prof Moncrieff believes these possible long-term effects should prompt patients to question whether antidepressants are still the right treatment for them.

‘If these were stunningly effective treatments, maybe it would be worth putting up with the risks,’ she says. ‘But the majority of the evidence shows they’re not much better than a placebo.’

An MHRA spokesperson said every antidepressant has its own ‘unique benefits and potential risks,’ and that side effects are clearly outlined in the prescribing information provided with each medication.

The spokesperson added: ‘We recognize the impact that side effects can have on quality of life.

‘It is important that patients continue taking their medication and do not stop or change treatment without first speaking to a healthcare professional. Anyone concerned about side effects, or who experiences symptoms they think may be related to their medication, should speak to their doctor or pharmacist.’