Commonly reported side effects of kava use include headaches, sleepiness, sedation, diarrhea, and distinctive skin rashes called “kava dermopathy”.[1][2][3][4][5] Kava use may increase the risk of low birth weight when consumed during pregnancy; however, this was reported in an observational study, so other risk factors leading to kava use (stress, for example) may have played a role.[6] Upset stomach is a rarely-mentioned side effect but is sometimes reported to occur more with kava than in placebo groups.[7][8]
The use of kava powder in very high doses (205 grams) has resulted in clinical effects similar to alcohol intoxication.[9][10] Occasionally, this may be called “kava intoxication”, since it’s been described as a somewhat-less-aggressive and happier state of “drunkenness”.[11] Consuming the herb in much larger quantities (3.6 to 13L of traditionally prepared kava beverage, estimated to be the equivalent of over 8,000 mg of kavalactones per day) as part of traditional kava sessions may put users at risk for short-term impairments in motor vehicle operation and cognitive response as well.[12][13][10][14]