The thing about kava is that it's not really a good substitute for any drug out there due to it's undesirable side effects, which include nausea, tiredness, expense, and route of administration (gulping a mud-like grog on an empty stomach). It's hard to determine this threshold, since many experience reverse tolerance with kava which means they feel nothing the first couple times and later finally feel it but wonder why it was worth it. I tried kava paste when I was 15, was a bit drunk at the time but even sober I felt no effect from it so forgot about it for 10 years. I tried extracts & capsules, no effect. Then I notice my local health food coop has it in root chip form so I try it again, i feel something but it's hard to tell if it's just cause my stomach's empty & finally getting something in it.
Recently I read "Getting Stoned with Savages" an exaggerated account of an American expat living in Vanuatu, & find out kava really can intoxicate you. I love the fact it's from the South Pacific & natural, so I order some root powder, prepare it properly and voila! it works, effects felt in 10 minutes, like alcohol except worse in every way. It's called grog for a reason, I mean it gives you a little empathetic buzz very similar to having 3 or 4 drinks, you're relaxed & might become talkative which makes you want more to keep it going, but then you will get nauseous & dizzy. Plus you have to eat at some point but with kava you won't get any buzz drinking it on a full stomach. The smell of it seems to get stuck in your nasal passages too which doesn't help your queasiness. Even experienced users have a hard time stomaching it and take it more for the anti-anxiety qualities than for a high. Most of the people who get excited about it are looking for a non-addictive substitute to alcohol, but alas alcohol is similar to the Winston Churchill quote "Democracy is the worst form of government, except for all those other forms that have been tried from time to time." My advice, if you must try it, buy a quality 1/4 lb. bag, don't get all irrational and but a whole kilo like I'm stuck with.....