One of the short comings of diphenhydramine as a hypnotic is tolerance ramps up very fast. As in days fast. The other one is how quickly it gets crazy balls. 50-100mg is enough for WEIRD dreams. Go a bit beyond 150mg and you’re talking auditory hallucinations. More than that and you brush up on hell raiser territory. And as dose goes up it’ll paradoxically keep you awake even as it makes you super drowsy. Which is not fun.
Doxylamine on the other hand is a kinda crappy antihistamine. But its a pretty damn good hypnotic, broadly considered the best and most reliable OTC non habit forming option. Tolerance doesn’t ramp up nearly as quickly, its even safer than diphenhydramine dosage wise. There are fewer side effects and interaction risks.
Though it’ll leave you groggy in the morning. And its still not recommended for use more than a few days in a row, or for long periods.
I switched to doxylamine for an OTC sleep pill after bennedryl got real weird years ago. But really only take it occasionally when things get bad. It works a hell of a lot better, and has worked longer. But things like a better mattress and pillows and some other changes had a much bigger impact for me.
We used to market it explicitly for that. As well as in every conceivable remedy from hair tonic to antacid. We have the FDA for a reason.
