On 11/28/2020 11:46 PM, John Kuthe wrote:
> Nyquil:
> What is the ingredient that makes you sleepy in NyQuil?
> Drowsiness is one of the major side effects of some antihistamines,
> such as diphenhydramine (Benadryl)\
> and doxylamine succinate (the antihistamine found in Nyquil).

I always thought it was the alcohol.
Probably both. Not to mention, just feeling better will help you fall
asleep.