Beta-blockers are commonly prescribed for the treatment of hypertension, coronary heart disease and cardiac arrhythmias. The best-selling beta-blocker in the US is metoprolol (Toprol, Lopressor); over 15 million Americans, and millions more around the world, are taking it.

However, unknown to nearly all patients and physicians, and barely mentioned in the medical literature, there is an unfortunately common side effect that my experience suggests is affecting as many as 10-20% of patients who are taking metoprolol or similar medications. The good news: it can be quickly and easily resolved. The bad news: both patients and physicians are unaware of its link to metoprolol, and patients remain on the metoprolol, with symptoms persisting for years.

Given the large number of patients taking metoprolol, and the simple intervention that can solve the problem, it is urgent to bring attention to this tragically overlooked side effect.

The Side Effect

However, unknown to nearly all patients and physicians, and barely mentioned in the medical literature, there is an unfortunately common side effect that my experience suggests is affecting as many as 10-20% of patients who are taking metoprolol or similar medications. The good news: it can be quickly and easily resolved. The bad news: both patients and physicians are unaware of its link to metoprolol, and patients remain on the metoprolol, with symptoms persisting for years.

The Cause

No major or recent studies have looked at this problem. I too was unaware of it until an amazing experience opened my eyes: I was seeing an 80-year-old patient with early dementia. I noted that she had been taking a type of beta-blocker that gets into the brain. I performed an “n-of-1” experiment, and switched her to a beta-blocker that doesn’t get into the brain. The improvement was so dramatic that at her return visit, her daughter remarked to me: “Thank you for giving me back my mother!” 

I began to pay more attention to this. I found that in response to my questions, some patients acknowledged feeling a little off, a feeling they had trouble describing. But the usual words that came up were “mental fog,” “mental dullness,” or just not feeling as sharp as they used to.

The simple, yet rarely considered solution to this problem

Tragically, this side effect and its simple management are almost universally overlooked. Beta-blockers can be categorized as either “lipophilic” or “non-lipophilic”. Lipophilic beta-blockers, which include metoprolol, carvedilol (Coreg), which is a combined alpha- and beta-blocker, and propranolol (Inderal), cross the blood-brain barrier and accumulate in brain tissue, causing these adverse effects. And, currently, metoprolol and carvedilol dominate the beta-blocker market. 

In contrast, non-lipophilic beta-blockers don’t cross the blood-brain barrier, and don’t cause these symptoms. And replacing a lipophilic beta-blocker with a non-lipophilic beta-blocker provides the simple yet rarely taken step that quickly eliminates this side effect. A day or two is all it takes, and many patients are amazed with the change in how they feel. Alternatively, if your physician believes you might not need a beta-blocker, the beta-blocker can be tapered and stopped.

The non-lipophilic beta-blockers include atenolol (Tenormin), bisoprolol, and betaxolol. Atenolol is the most widely prescribed non-lipophilic beta-blocker, but its absorption from the GI tract varies considerably from person to person. For that reason, I prefer bisoprolol, which is more reliably absorbed. I usually prescribe ½ of the 5 mg pill, and increase to 5 mg if necessary. In my experience, most patients do not need higher doses.  Bisoprolol also has another advantage: a given dose results in a much more predictable blood level than do the lipophilic beta-blockers. 

For all of these reasons, in almost all patients, when I prescribe a beta-blocker, I usually prescribe bisoprolol.

That said, most physicians are unfamiliar with bisoprolol, and few prescribe it. You will have to suggest it to your physician. 

Is there any advantage to prescribing metoprolol?

Frankly, no. Even the ability of beta-blockers to reduce anxiety has nothing to do with getting into the brain. It results instead from inhibition of the effect of circulating adrenaline, regardless of whether it gets into the brain or not. 

Yes, large confirmatory studies are needed. But in the meantime, greater awareness of the problem, and of the effectiveness of this simple, and safe, modification in treatment, make it urgent to act now, as it could quickly, easily, and dramatically, benefit so many patients.

I urge you to discuss this information with your physician. And, since so many people are taking metoprolol or carvedilol, I urge you to share this article with as many people as you can to get the word out about this common, yet unnoticed and easily remediable problem that is affecting the lives of so many. 

Please note: I do not have any financial conflict of interest whatsoever with regard to bisoprolol.