I have used phenibut on and off for the past year. Start your first few doses low, about 500mg to 1.2 grams. After a few times using it you can increase to 1.5 to 2 grams. This has avoided negative side effects with me. This substance is not a supplement. It is a drug. But, it seems to have nootropic like effects, increasing concentration, neuroprotection, and antioxidant properties. It has a long half life. I take it at 5:00 pm (once or twice a week) and I can sleep soundly that night and feel it fo half the next day. It has profound benefits in helping social and general anxiety. These effects are real not imaginary. It also seems to potentiate opiates, alcohol, and benzos. I have repeatedly found this out, so be careful (this can be a good thing). I have found that it helps WDs.
Use it one week on, one week off or as I do: once or twice a week. It might be somewhat addictive, I havn't used it on enough consecutive days to find out. Start out with low dose and take care.