Yes, obviously. You can overdose on anything.
But, the question for me is what kind of effect it has after taking a normal amount many days in a row. Turns out: I have no idea.
There’s all kinds of dire consequences online, like nausea, vomiting, seizures, renal failure, death and this gem:
If doxylamine is consistently abused, it can cause the user to form lesions on their brain which affects memory, cognitive ability and emotions.
So, that sounds, you know, NOT GOOD. However, it seems that most of the abuse people are worried about — particularly if the questions internet users choose to post on the superhighway are any indication — is more along the lines of how it would affect you if you swallowed a whole bottle of Nyquil in one night or multiple bottles with alcohol over multiple nights. There’s really not a lot of information about what happens if you’re not actually trying to Nyquil all your problems away and instead just take slightly more than the prescribed amount in order to fall asleep without coughing for way too many nights in a row. The only indication that this is not totally advised is the note on the bottle that pretty much says if you still have to take this shit for more than two weeks, then you should see a doctor.
So. There’s that.
I’m mostly better. Maybe. Probably. Who knows. But, I’m still coughing myself awake at night. If I didn’t need to sleep, I’d be fine. And, if I didn’t have to go to jury duty today I would have gone to the doctor. Then, I think jury duty made me sicker — sick about the system, man.
I also got through a 1:20 easy bike ride yesterday without wanting to run my bike over with someone else’s car, by laying down in front of it. And, I didn’t even take Dayquil to do it (largely because I don’t believe in Dayquil — you should not be going about during the day passing around symptoms that are so bad you need to cover them up that much — and also one time I took some to get through a race and, well, lesson learned).