Thousands of patients in the UK could be at risk from dangerous drug interactions, doctors have warned—after new research found that taking antidepressants alongside beta blockers may trigger life-threatening heart problems.
Both medicines are widely prescribed: around 8.6 million people in England were given antidepressants last year.
A further 60,000 patients are prescribed beta blockers annually for heart conditions or, increasingly, to calm the physical symptoms of anxiety such as palpitations and shaking.
Scientists studied 65 adults with both depression and high blood pressure and found the combination of the two drugs increased the risk of dangerously low blood pressure and abnormally slow heart rate.
All were taking a beta blocker together with antidepressants such as SSRIs and SNRIs—the most commonly used drugs for depression and anxiety, including fluoxetine, sertraline and venlafaxine—as well as duloxetine and bupropion.
The researchers found the highest risk with a group of medicines known as CYP2D6-metabolised beta blockers—including metoprolol, carvedilol and nebivolol.
These are broken down in the liver by an enzyme called CYP2D6. If that enzyme is blocked by another medicine, such as certain antidepressants, the beta blocker can build up to unsafe levels in the body.
A new study has revealed taking anti-depressants and beta-blockers together can cause potentially life threatening heart problems
The analysis revealed those on this combination had a 15–20 per cent drop in blood pressure and a 25 per cent higher risk of bradycardia, where the heart beats abnormally slowly.
Severely low blood pressure can cause dizziness, fainting, organ damage and even shock, when vital organs are starved of oxygen.
Bradycardia raises the risk of seizures, blackouts and cardiac arrest.
The findings were unveiled at the American Heart Association’s Hypertension Scientific Sessions 2025.
‘We expected interactions, but the magnitude—particularly between nebivolol and other beta blockers broken down by CYP2D6—was striking,’ said study lead Dr Inshal Jawed, of Dow Medical College in Karachi.
The team noted this effect was not seen in people taking atenolol or nadolol, which are processed differently in the body and less likely to interact with antidepressants.
Dr Jawed said: ‘Clinicians should be cautious when prescribing CYP2D6-metabolised beta blockers with SSRIs or other CYP2D6 inhibitors.
‘Dose adjustment and close monitoring are key, while beta blockers less reliant on liver metabolism may be safer alternatives.’
But she added that larger studies are needed, as the analysis involved only a small group of patients.
The warning signs of low blood pressure include dizziness, blurred vision, nausea, fainting and confusion.
Symptoms of bradycardia include chest pain, extreme tiredness, shortness of breath and difficulty concentrating.
The findings come amid growing concern over the rising use of beta blockers for anxiety.
Propranolol, first developed to treat heart disease, has become a go-to pill for calming nerves in stressful situations.
By blocking the effects of adrenaline and noradrenaline, it slows the heart, lowers blood pressure and dampens physical signs of stress such as shaking, sweating and palpitations.
But experts warn there is little evidence it helps long-term with chronic anxiety or panic attacks—and that prolonged use may even increase the risk of death.
Celebrities including Kristen Bell and Rachel Sennott have credited beta blockers for keeping them calm in high-pressure situations.
Dr Amir Khan, a GP, said many doctors prescribe them for ‘situational anxiety’—for example, before a big public speaking event. ‘So, if and when, rather than long term,’ he explained.
While not addictive, taking more than the prescribed dose can be dangerous.
Common side-effects include tiredness, dizziness and sleep problems, while more serious risks include heart failure, breathing difficulties and severe allergic reactions.