I used to snort methylphenidate for kicks and would usually go thru 4-10 20mg pills a night. the entire time i was experimenting with siberian ginseng, ashwagandha, rhodiolia (mostly all in extracts, but seemingly reliably quality ones). If i experienced anything as a result of this combo per se i would say that it led to a better high, at first. MPHD kinda starts to suck after the first hour or two no matter what, so you're never going to feel that great. there were allways too many side effects for me, the drug wasn't fun. Now was this because I was taking any of these similar herbs, including L-theanine? No it has nothing to do with it-- unless you're VERY naive to stimulants or have a particular sensitivity to one of them, or something spooky inside you, you be fine, as long as you pay close attention to you body. Don't increase any dose of either together unless you feel perfectly fine; otherwise, if something doesn't feel as good when you mix them, then listen to your experience because it may be telling you of what your needs are. Korean Ginseng is a highly revered, highly studied herb; it's also very expensive to find quality specimen, and L-theanine I take every night. It is really, really safe stuff.