Interactions with Kava Kava

The German Commission E monograph for this herb indicates that kava may potentiate the effects of substances, such as barbiturates and other psychopharmacological agents (Blumenthal 1998). There has been a case report of an interaction between alprazolam and kava that resulted in coma in a 54-year-old man (Almeida and Grimsley 1996). Although the patient's medications also included cimetidine and terazosin hydrochloride, the kava-alprazolam interaction was presumed to be the cause of his condition. Information regarding the doses of kava or alprazolam was not included in the report but the patient denied overdosing on either substance.

Levodopa

There is a case report of a possible interaction between kava and levodopa (Schelosky et al. 1995). Kava reportedly decreased the effectiveness of levodopa, presumably because of dopamine antagonism. The patient was a 76-year-old female who had been maintained on levodopa (500 mg/day) for eight years for the treatment of Parkinson's disease. When kava extract (150 mg bid) was added to her medication regimen, she noted an increase in the duration and number of dyskinetic episodes within 10 days. Discontinuation of the kava resulted in a return to baseline patterns for this patient within two days.

Phenothiazines

Patients taking phenothiazines may be at increased risk of developing extrapyramidal side effects if these medications are combined with kava (Schelosky et al. 1995).

References

Almeida JC, Grimsley EW. Coma from the health food store: interaction between kava and alprazolam. Ann Intern Med. 1996;125:940-941.

Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Boston, Mass: Integrative Medicine Communications; 1998.

Schelosky L, Raffauf C, Jendroska K, et al. Kava and dopamine antagonism [letter]. J Neurol Neurosurg Psychiatry. 1995;58(5):639-640.

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