What's the latest thinking on diphenhydramine?
May 13, 2021 8:28 AM   Subscribe

A few years ago, Metafilter discussed a study suggesting that long-term use of diphenhydramine could be damaging. I'd like to know what the latest thinking is on this subject. To what extent should my family be avoiding the stuff?

My two-year old son occasionally has a stuffy nose and puffy eyes. His doctor took a look, said that he had seasonal allergies, and told us to give him 6.25mg of diphenhydramine every night, and 1.25 mg of desloratadine every morning indefinitely.

My spouse frequently takes diphenhydramine for allergies.

I very occasionally take it to help me sleep.

I'd like to learn more about current thinking in the medical community about this. Is our use of diphenhydramine safe?
posted by HoraceH to Health & Fitness (3 answers total) 8 users marked this as a favorite
IANAD but my allergist was concerned about the amount of diphenhydramine I was taking (probably 2-4 times a week during spring/fall, very infrequently the rest of the year) and prescribed me Azelastine, a nasal spray that has CHANGED MY WHOLE LIFE (I had tried flonase/nasacort etc. to little success, and I also still take Xyzal and allergy shots); I like, no longer have allergy symptoms, whereas I used to be incapacitated to the point where I would just take the benadryl and sleep all day. Again IANAD and I have no idea about your son, but it might be worth asking about for your wife.

I definitely think it's worth asking an allergist this question and not just a GP, if that's what you've done so far. When I asked my GP about my benadryl use she was like "sure, why wouldn't it be fine!", whereas my allergist was much more up to date on the research and was like "well, your usage isn't THAT high, but it's still better to avoid it so let's try something else".
posted by goodbyewaffles at 8:37 AM on May 13, 2021 [4 favorites]

It's in a class of drugs called anticholinergics, and there are real cognitive risks. There are a lot of articles linking it to dementia in older people, and linking sustained or greater use of diphenhydramine to increased risk of dementia - you can Google to see a bunch of them. The ones I glanced at were all later than 2010.

It's also linked to problems concentrating and remembering, but most of the info I've found is from studies with older adults. I certainly wouldn't give it to a child on a regular basis if another allergy drug would work, but it might be worth asking another doctor.

As an adult, I try to avoid diphenhydramine and other anticholinergics as much as possible. There is one drug I used to take frequently for nausea associated with migraine -- it was _great_ -- but I got motivated to find other drugs because of the risks.

Can allergy medications harm your brain?

Diphenhydramine may improve sleep but tolerance develops quickly and may disrupt cognitive functions including memory.

posted by amtho at 10:09 AM on May 13, 2021 [2 favorites]

Response by poster: Thank you for your reples, goodbyewaffles and amtho! We have made an appointment with an allergist. My spouse is excited to try Azelastine!
posted by HoraceH at 10:38 AM on May 17, 2021

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