You build up a quick tolerance to phenibut so use it sparingly. And for some reason it’s never as good as the first time. 2.5 grams is a good dose. It can take upto 4 hours to kick in so don’t do more because you don’t feel anything. Also be careful if you are drinking as it can really f*ck you up. I know people who have taken 10 grams and got a wicked hangover that lasted for two days so proceed with caution.
I use a bunch of nootropics that I cycle except for Alcar. ALCAR is a very subtle nootropic and is a good one to start with. I take 2grams/ twice per day and the effects is noticeable. I’m not run down at the end of the day, I’m still mentally sharp.
ImmInst.org has a forum section that has more info about nootropics than you’ll ever need.