I bought a tub of caffeine powder to add to my daily stims, and it seems to agree with me. I've been cautiously working up the dosages and getting a feel for them for the past few days; I took about 750mg over the course of today, and I feel more calm and centred than usual. My skin's a little dehydrated and flakey, but I get that with tea sometimes, and chain-drinking cups of tea has other effects that I haven't encountered with the caffeine powder so far, like giving me muscle cramps and sticky eyelids by causing me to piss out my electrolytes, or irritating my stomach with tannins.