Exactly....I was just about to give the same warning. The Indians brewed it very dark (hence the Spanish name, black drink) and used it in religious ceremonies for “cleansing” purposes. It also caused a rapid heartbeat and hallucinations.
If you don’t get carried away and make it too strong, however, it’s a drinkable, black-tea like beverage, although it tastes a little too “leafy” for me.