Kanna is absolutely incredible. There certainly is a reverse tolerance. I feel like there is a 'screening process' with kanna, where it probably won't work well enough your first few tries, which will deter 90% of people who try it. When you prove yourself worthy and dedicated to the plant, it starts to reveal it's effects. Then eventually you can't ignore the effects and it becomes a rather strong drug. If nicotine is dopaminergic, then kanna is the serotonin-oriented comparison. I believe there actually are small amounts of nicotine in kanna.
Oral has proven the best method for me. All ROA's have produced effects, with oral being the most enjoyable. Smoking comes in a close second especially when drinking alcohol or using mushrooms. I've tried snorting kanna repeatedly over the course of many evenings and I always find the effects disappointingly weak. It's a very long-lasting drug too, I find subtle anti-depressant effects lasting for days. It's extremely recreational for me, almost purely. I find myself refraining from using it if I need to focus or keep my composure because it definitely can be distracting and occasionally over-stimulating. As mentioned above, it's extremely similar to the first alerts of an MDMA roll, but never quite reaches that explosion of euphoria.
The effects go something like this for me:
Take ~500mg of freshly powdered kanna and add to a shot glass of warm water, mix well but don't expect it to dissolve.
Drink it down quickly and chase with a soda or something.
Placebo effects are reliably felt immediately, which indicates that my body reacts positively to simply knowing it's going to receive kanna.
About a half hour or less after ingestion, I first notice warm rushes akin to kratom/opiates/alcohol and a stimulation similar to caffeine but slightly different.
Stimulation continues to build and can even get slightly jittery, but no where near as bad as a caffeine OD. A strong desire to move around starts to take hold. For lack of a better description, I start to feel like I care less about everything but not completely disconnected. Euphoria is not the right word but definitely can feel content with the world.
Pressure behind the eyes begins to build, pleasurably forcing them to open wide (again, similar to MDMA/speed). Pupils will dilate, sometimes as severely as MDMA (seriously).
Color saturation is notably increased, akin to mushrooms. Everything takes on a softened, saturated, psychedelic appearance. Objects and patterns become very interesting, I find myself closely observing details of surfaces.
Eye sight gets extremely sharp. Not only do I notice I can see clearer and further, but the details of things almost jump out at me, again very much like psychedelics. Just the other day I had 500mg oral before work, and by the time I was at my desk, I was putting coffee creamer into my coffee and this was more fascinating than a nature documentary, I couldn't look away from it. Extremely distracting! I also wanted to get up from my desk and run around which caused me to be very ansy and anxious at work. This is why I usually avoid kanna in such situations.
After the initial come up, it levels out into a very smooth and subtle effect. The color saturation, visual effects and pupil dilation will last a very long time, careful driving like this. Cops don't take kindly to saucer-eyed drivers even if it does actually mean you're hyper-focused.
I notice a long lasting "okayness" with everything in life. Life can be hard, stressful, depressing, unfulfilling, and I find kanna makes me a lot less negatively affected by life's anxieties. My mind dwells on the past far less and more so on the right-now. It doesn't numb me out to where I can't care even if I wanted to (like benzos) or make me blindly euphoric to where I try to hug my enemies (like opiates), it simply instills this...again for lack of a better word..."okayness". I have found said "okayness" effect to sometimes last several days. This feeling alone has blasted me out of many funks. It makes you feel ridiculous for ever having felt depressed, if you know what I mean.
I've yet to experience this later-stages sedation everyone talks about. I feel like kanna is stimulant through and through, keeps me focused, content and awake all night long, without actually keeping me awake should I choose to lay down. I've never felt actually sedated from it. Never felt any negative after effects either. I've gotten an occasional mild headache after using kanna, but that's not proof the kanna caused it, I get headaches all the time, and it wasn't that bad anyway.
I'm surprised that this herb is not way more popular than it is. Mother Nature has lots of weak/ineffective psychoactive herbs. She definitely got it right this time!