re: Kanna - A Natural SSRI for anxiety and panic attacks.
Quoted off Wikipedia
"The alkaloids contained in Sceletium tortuosum believed to possess psychoactivity include: mesembrine, mesembrenone, mesembrenol and tortuosamine. Mesembrine is a major alkaloid present in Sceletium tortuosum, and due to the antidepressant effects of kanna many have been lead to believe that mesembrine is a potent SSRI, however there is a lack of research to prove this, and a study  has shown that mesembrine is more likely to be a Phosphodiesterase4-selective inhibitor, similar to rolipram, rather than an SSRI. Despite this, kanna should not be combined with other SSRIs, MAOIs, cardiac or psychiatric medications. The results of taking sceletium on top of other SSRI's are unpredictable, and it is known that alcohol can also cause side effects combined with many SSRI's. Headaches in conjunction with alcohol have been noted with sceletium use."
Quoted from IAMSHAMAN when I bought it
WARNING! Kanna is believed to act as a Selective Serotonin Reuptake Inhibitor (SSRI). In combination with common psychiatric medications including other SSRIs (such as Prozac) and MAO Inhibitors, it may cause injury if ingested.