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Comment by jmalicki | Hacker News Reader

The article is extremely short, but comparing 2-4 OTC doses of diphenhydramine to a level of alcohol concentration above what constitutes a DUI in most places seems like an odd choice? Or is that just a matter of proof of concept, go for the big obvious demonstration first?

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The directions I'm looking at for a store brand diphenhydramine say to take 1-2 of the 25mg tablets as needed, so I'd expect that's the typical therapeutic dose.

2 doses of diphenhydramine can have very noticeable and profound effects on many people, 50mg total isn't a light dose by any metric. That seems fine as a comparison to 0.1% BAC.

But 60mg Fexofenadine makes no sense to me in comparison. It's usually 180mg in a single pill.

Hate to break it to you, but 50mg is pretty much a common dosage for most people taking Diphen. At least where I lived over the past few decades... This is mostly due to the effect of 'if 1 pill is almost enough to do the job, then 2 pills should be adequate'. You see this a lot with people who take Tylenol and/or Advil. Tylenol overdoses are more common because of the frequency of acetaminophens use in other medications in combination with people taking Tylenol not realizing they are doubling/tripling their doses.

So having people end up driving on 50mg+ doses of the dryl is not uncommon in places like Canada. Pair it with a dose or two of pseudoephidrine hydrochloride as well, and you basically have a breath easy cocktail that might put you to sleep, or might keep you awake all night.

> So having people end up driving on 50mg+ doses of the dryl is not uncommon in places like Canada.

Yeah this makes sense to me. We have lots of people driving around at 0.1% BAC too.

Having done that for awhile once? It basically is, and that is the typically OTC recommended dose.

Sure, but you should always check basic mg/kg numbers before you take a drug. Diphenhydramine can be hallucinogenic in high doses.

They also sell 1-gram extra-strength Tylenol pills OTC, but that's a very high dose for an average person. And what do you know, acetaminophen is the leading cause of acute liver failure in the US.

What is your point exactly?

That typical OTC doses for a common antihistamine ARE probably equivalent in impairment to being legally drunk for most people is mine?

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