FOAF took a whole bottle (not sure what kind, but definitely OTC) in a suicide atempt. Not sure how close he was to death, but I did see him have a seizure as the medics were getting him onto a stretcher.
Pretty unlikely to happen with normal dosing, even over a long time.
Not impossible, though.
The big problem is that antihistamines can make worse a case of elevated intra-ocular pressure, which the person may not have been previously aware of. This can trigger a crisis.
And Will Repair is quite wrong.
Thanks for the reply.
Will Repair. In case you revist this thread, please make sure you understand that black and white answers about medical(and legal) questions are NOT appreciated on the Straight Dope when uttered by people who aren’t qualified to give such an answer. I would strongly suggest you not do this again.
samclem GQ moderator
There is currently a case being investigated in the Bay Area about a Stanford student who disappeared and was found dead in the trunk of her car.
The most recent development in the case is that the examiners found very high levels of diphenhydramine in her system and are thus ruling a suicide. Her family is adamant that she wouldn’t commit this offense and are now looking for whoever forced her to take the pills.
Wait, she was found dead in her trunk and they don’t suspect foul play?
:dubious: 
:mad:
(Sorry for smiley abuse)
You can OD, but it takes more than a couple, as QtM, chaoticbear and ladyfoxfyre said. Most dudes can take two safely (that’s half of the max dose), but I’d call your Doc or his “advice nurse” and double check, because everyones metabolism is different. And although 2 could be safe, if you had a drink along with them, you most certainly shouldn’t drive and you could fall and hurt yourself. Please do not take this as “medical advice” take this as something you should talk over with your MD. (My MD has OKed some rather high dosages of an OTC medicine, but only after a physical and he knows me well)
You can buy generic diphenhydramine at the discount store a bottle of 100 for a couple of bucks. Don’t shell out big bux for OTC sleep aids. Exact same medicine.
Melatonin will help, but it’s not a “sleeping pill”.
For some an aspirin helps. Note that many take an aspirin a day for their blood (this is something you should discuss with your Doc), why not at bed time?