“The toxicities associated with diphenhydramine are dose dependent. Common signs and symptoms of overdose include confusion, urinary retention, tachycardia, blurry vision, dry mouth, irritability, and hallucinations.2Diphenhydramine-induced QRS widening and QTc prolongation can be seen on an electrocardiogram. With ingestions greater than 1 gram, diphenhydramine may result in delirium, psychosis, seizures, coma, and death.5There is an even greater risk of seizures, coma, and death when ingestions are greater than 1.5 grams of diphenhydramine.6 Fatal deaths have also been reported with oral doses greater than 20 mg/kg.3”
I wouldn’t do it. It’ll be sick-feeling trip. If you don’t fall asleep first.