Several common medications can affect a brain chemical called acetylcholine, a neurotransmitter that plays an important role in memory, focus, and clear thinking. When medications interfere with this signaling pathway, some people notice symptoms like forgetfulness, slowed thinking, or mental fog. These changes can easily be mistaken for normal aging, but sometimes the medication itself is contributing to the problem.
If you’re noticing that several of these medications have something in common, you’re right. Many of them belong to a group of drugs known as anticholinergics—medications that block the neurotransmitter acetylcholine.
These drugs are widely used and often very helpful, but they can sometimes affect memory, alertness, and mental clarity, especially when several are taken together.
I explain this in much more detail in another article I wrote called “7 Things to Know About Anticholinergic Drugs and Brain Fog.” If brain fog, forgetfulness, or slowed thinking has crept up on you—or someone you love—that article will help you understand what’s going on and what questions you might want to ask your doctor or pharmacist.
👉 You can read it here: 7 Things to Know About Anticholinergic Drugs and Brain Fog
• Certain allergy medications – Some antihistamines, especially older ones such as diphenhydramine or chlorpheniramine, block acetylcholine. This chemical helps regulate memory, attention, and learning. When acetylcholine signaling is reduced, people may feel unusually drowsy, mentally slowed, or foggy. Over the years in pharmacy practice, I’ve seen many patients assume they were “just getting older,” when in reality their allergy medicine was quietly affecting their alertness.
• Bladder control medications – Many medications used for overactive bladder (such as oxybutynin or tolterodine) work by blocking acetylcholine to relax bladder muscles and reduce urgency. Unfortunately, this same neurotransmitter is also important for brain function. When acetylcholine is suppressed throughout the body, some people notice forgetfulness, trouble concentrating, or a feeling that their thinking isn’t quite as sharp as usual.
• Some sleep aids – Many over-the-counter sleep products contain diphenhydramine or similar antihistamines that have strong anticholinergic effects. While these medications can make you sleepy at night, they often linger in the body longer than people expect. The result may be next-day grogginess, slowed thinking, or a “mental haze” that can feel surprisingly similar to cognitive aging.
• Certain antidepressants – Some antidepressants—particularly tricyclic antidepressants and certain older medications—have anticholinergic effects that can interfere with normal brain signaling. In some individuals this may lead to brain fog, difficulty concentrating, or mild memory lapses. Newer antidepressants tend to have fewer of these effects, but medication responses still vary widely from person to person.
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Suzy Cohen, has been a licensed pharmacist for over 30 years and believes the best approach to chronic illness is a combination of natural medicine and conventional. She founded her own dietary supplement company specializing in custom-formulas, some of which have patents. With a special focus on functional medicine, thyroid health and drug nutrient depletion, Suzy is the author of several related books including Thyroid Healthy, Drug Muggers, Diabetes Without Drugs, and a nationally syndicated column.
