St. John's wort and schizophrenia
CMAJ 2000;163(3):262-3
In recent years St. John's wort has become a popular natural medicine for the treatment of depression1 and general symptoms such as tiredness and lack of energy. Unfortunately, the potential harmful effects of St. John's wort have not been fully recognized. It inhibits monoamine oxidase2 and
the reuptake of serotonin and norepinephrine.3,4 Such mechanisms of action underlie the therapeutic effects of antidepressants. Like antidepressants, St. John's wort may induce mania and hypomania.5,6 Antidepressants may exacerbate psychosis in patients with schizophrenia;7 this raises the possibility that St. John's wort may have a similar adverse effect. To our knowledge this has not been previously described. We report 2 cases in which patients with schizophrenia experienced psychotic relapse that was temporally associated with the consumption of St. John's wort.
The first patient had been admitted to hospital because of schizophrenia at age 26. Following complete remission, perphenazine therapy was stopped and the patient remained well without medication for 3 years. Five months before her relapse she purchased a bag of St. John's wort herbs from a natural food store, and once or twice a week she placed some of the herbs in tea and consumed it. Two months before her relapse she consumed the herbs daily. She became acutely psychotic with paranoid delusions, ideas of reference and loosening of associations. Her psychosis responded to olanzapine. She did not take street drugs. On occasion she had taken other herbal products, but not regularly.
The second patient was first treated for a paranoid psychosis at age 34. He rapidly responded to treatment with risperidone. After 6 months the medication was stopped. He did well without any medication for another 7 months, at which time he experienced an abrupt recurrence of persecutory delusions, ideas of reference and bizarre behaviour over a 2-week period. His schizophrenic episode responded to risperidone. Two to 3 months before his relapse he had purchased St. John's wort at a health food store and had been taking it daily.
It was only after the condition of these patients improved that information was elicited on their use of St. John's wort; they were unable to provide details beyond the information described here. These 2 cases do not establish a cause–effect relation, but they do raise the possibility that relapse was associated with taking St. John's wort. Given our current knowledge about the pharmacological properties of St. John's wort it is important that physicians ask their patients whether they take natural products and caution them about potential harmful effects.
Samarthji Lal
Hani Iskandar
Department of Psychiatry
McGill University
Montreal, Que.
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References
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