I've taken picamilon for anxiety. I took it for over 2 weeks with no side effects. Picamilon is a mix of GABA and vitamin 3. In general, I felt mentally better than I usually do (anxiety, explained and unexplained mood swings). I haven't tried any other GABA supplements. I think it is OK to take long term. It is supposed to have next to no side effects. Most studies appear to involve animal testing, though, which always makes me suspicious. This is all the information and experience I have, so definitely get more opinions.