I'd recommend maybe 200 mg - 300 mg to get a taste for diphenhydramine's deliriant effects. And, remember that is what it does, it induces delirium. My first and only time I did a higher dose I did either 250 mg or 300 mg, can't remember, but that gave me a good taste as for what diphenhydramine is like without going completely nuts. I was also on benzos at the time (dependent), and an SSRI. Diphenhydramine is rarely reported to be "euphoric", and often the opposite "dysphoric". The delirium it induces can be frightening, and there is a mood change, a "cold" feeling as well. It is a trip though, not psychadelic at all, but it is a trip. It is almost like a really heavy opiate-nod without any of the pleasant effects of opiates, and much more delirium as well as hallucinations. There are usually a lot of "diphen spiders" which are often perceived as actual spiders, other insects, or just spots. You may not know what you are really doing on higher doses even if you feel like you do. People often report smoking imaginary cigarettes, or talking with a hallucination. I don't advise against it if you are in a safe enviroment, and have good overall and cardiac health, but you may not enjoy it. It is a bit of twisted drug.
