Doctors in the UK have raised concerns about potentially hazardous drug interactions that could affect many patients. Recent studies indicate that using antidepressants alongside beta blockers may lead to serious heart problems.

Both medicines are widely prescribed: around 8.6 million people in England were given antidepressants last year. 

Each year, around 60,000 individuals are prescribed beta blockers for heart-related issues or to help manage physical anxiety symptoms like heart palpitations and tremors.

A study involving 65 individuals with both depression and hypertension revealed that this drug combination heightened the risk of significantly low blood pressure and an unusually slow heart rate.

Participants were using beta blockers in conjunction with antidepressants like SSRIs and SNRIs, which are widely used for treating depression and anxiety. These include medications such as fluoxetine, sertraline, venlafaxine, duloxetine, and bupropion.

The research highlighted that the greatest risk was associated with a specific category of beta blockers known as CYP2D6-metabolized types, which includes metoprolol, carvedilol, and nebivolol.

These beta blockers are processed in the liver by the enzyme CYP2D6, and if this enzyme is inhibited by other medications, like some antidepressants, it can cause the beta blocker to accumulate to dangerous levels in the body.

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.