People taking two widely used drugs could be at greater risk of potentially fatal heart conditions, new research has found.
Roughly 8.7 million Brits take antidepressants and around 50 million beta blocker prescriptions are handed out annually, often for anxiety and heart conditions.
But taken together, the drugs could increase the risk of dangerously low blood pressure and abnormally slow heart rates, data shows.
However, the study included a small sample of just 65 participants and scientists say more research is needed.
The findings were announced at the American Heart Association’s Hypertension Scientific Sessions 2025.
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Study lead Dr Inshal Jawed told Medscape Medical News that researchers had expected the drugs to interact but not to the ‘striking magnitude’ they found.
The research found that combining the two types of drugs could lower blood pressure by up to 20% and raise the risk of a slow heart rate by 25%.
Dr Jawed, of Dow Medical College in Pakistan, said clinicians should be ‘cautious’ when prescribing CYP2D6-metabolised beta blockers with SSRIs or other CYP2D6 inhibitors.
CYP2D6 is an enzyme that helps break down beta blockers but SSRIs could hinder that process, the research found. Common SSRIs include fluoxetine and sertraline.
Signs to watch out for include dizziness, blurred vision, nausea, fainting, confusion, chest pain, extreme tiredness, shortness of breath and difficulty concentrating.
Dr Jawed said dose adjustment and close monitoring were key, while beta blockers less reliant on liver metabolism could be safer alternatives.
‘Larger, prospective clinical studies are needed to confirm these pharmacokinetic changes and assess their impact on real-world patient outcomes,’ Dr Jawed added.
Low blood pressure can cause everything from dizziness to organ failure, and a low heart rate can cause cardiac arrest.
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