Side effects -- many people have experienced a temporary worsening of symptoms jsut after beginning, which go away after a little while longer. i.e., my skin broke out pretty bad but then cleared up and was better than ever within a couple days' time.
Calm -- I think OP has mood-elevating and anti-depressant effects. Trapper found an article a couple of months ago that talked about the presence of opiod-like substances in saliva and it made perfect sense to me! I usually experience a lot of the fall/winter blues Oct.-Jan. and I was fine this past winter season (so far!). I can't take anti-depressant meds, so this was a big deal for me. I also find that the action of OP itself is calming and meditative. i.e., the swishing. (in contrast, I never find, say, the morning rush to the toilet after a Liver Flush
Other benefits I have seen: increased sinus/nose health. In past years I have taken tons, and I do mean tons, of over the counter cold/sinus meds each fall. (We will see about the spring, my next test!) This year -- none. That's also a big deal for me (and my wallet, as for some reason I could never get it together enough to buy the big pack of them, so I would go to 7-11 and buy the pretty expensive single doses 2 or 3 times a day!).
I would love to try the hemp oil. I am on a bit of a budget these days but some people around here I respect a lot really love it! Go for it.
My current blend is sesame with a couple of drops of oil of oregano. I am seeing whiter teeth, and *brighter* teeth and eyes, continued ability to breathe through my nose despite some very dry heat (again, this is a big deal for me!), clear skin.
Good luck and happy pulling!