According to this article, Mutaflor increases Serotonin: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4663480/ I've been taking Symbioflor 2 for a week now. Initially, I thought the mood symptoms (agitation, spaciness, derealization etc.) were due to a herx, but I'm starting to wonder if they may be due to serotonin modulation. Is that plausible, and if so, should I stick it out? I never did well on SSRIs etc. though they typically made me numb, whereas since starting the Symbioflor, my mood is far more labile and I want to cry all the time.