Caution: Aside from the reported interactions, kava inhibits a number of the cytochrome P450 enzymes that play a role in the breakdown of many medications.¹⁴ Therefore, kava has the potential to interact with a wide range of medications, even if such interactions have not yet been reported. Individuals taking any medication who wish to use kava should check with their physician or pharmacist to determine whether inhibiting cytochrome P450 could cause an adverse drug interaction.

Kava should not be taken together with other substances that also act on the central nervous system, such as alcohol, barbiturates, antidepressants, and antipsychotic drugs. One study found that large amounts of a traditional kava preparation did worsen cognitive impairment caused by alcohol consumption.¹⁵ However, at the amounts recommended above, kava does not appear to impair cognitive performance. Kava has also been reported to cause excessive sedation and grogginess when combined with benzodiazepines.¹⁶ One study found it was safe to drive after taking kava at the amounts listed above.¹⁷ However, the German Commission E monograph states that kava, when taken at the recommended levels, may adversely affect a person’s ability to safely drive or operate heavy machinery.¹⁸