A top United States (US) health expert has issued warning that common tablets taken by millions of people in United Kingdom may increase dementia risk, particularly sleeping drugs.
Dr. Amy Shah, an immunity and diet specialist trained at Harvard, Cornell, and Columbia universities, has raised concerns over the use of medications containing diphenhydramine.
She made this call while urging her followers to stay away from such drugs recently.
These include widely available UK brands such as Nytol One-a-Night, Boots Sleepeaze, and Panadol Night, as well as US brands like Tylenol PM, Unisom, and Benadryl.
Dr. Shah’s warning comes amid mounting research linking long-term use of anticholinergic medications—such as diphenhydramine—to cognitive decline.
Anticholinergics work by blocking acetylcholine, a neurotransmitter critical for learning and memory.
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One alarming study, published in 2015, tracked 3,500 older adults and found that those who took anticholinergic medications for three years or more had a 54% higher risk of developing dementia.
Dr. Shah’s viral social media post, viewed more than three million times, strongly advised against the regular use of diphenhydramine-containing products. She stated: “ ‘I know it’s over-the-counter, I know you’ve had it since you were kid, but we know lot more now. You should not be using these medications regularly.”
In the US, diphenhydramine is commonly found in Benadryl products, but it is not as frequently used in UK allergy medications.
Dr. Shah recommended alternatives such as Zirtec, Allegra (sold as Allevia in the UK), Clarityn, and Zyzal, which do not penetrate the blood-brain barrier as much as older antihistamines.
With dementia cases projected to rise from 900,000 to 1.7 million in the UK over the next two decades, researchers stress the need for alternative treatments, particularly for older patients prescribed medications for bladder control.
Despite these concerns, not all anticholinergic medications showed a dementia risk.
The study, published in the British Medical Journal, found that drugs such as darifenacin, fesoterodine fumarate, flavoxate hydrochloride, propiverine hydrochloride, and trospium chloride were not linked to increased dementia risk.
A non-anticholinergic alternative for overactive bladder, mirabegron, showed some potential risk, but researchers noted that more data is needed.
The manufacturers of Nytol, Panadol Night, Benylin, and Boots were approached for comment regarding these findings according to Daily Mail.
As awareness grows, experts urge both medical professionals and consumers to reconsider the frequent use of anticholinergic sleep aids and explore safer alternatives for sleep and allergy management.
