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St. John's Wort (Lat. Hypericum) is one of the best-known herbal medicines, and has attracted extensive media attention. But, like all herbals, St. John's Wort is a chemically active compound that should be used carefully, with the advice of a trained health practitioner. Special caution may be required when St. John's Wort is used in conjunction with, or to replace, selective serotonin reuptake inhibitors (SSRIs) such as Prozac, Paxil, Zoloft, or Zyban, all antidepressants that enhance serotonin levels. In my own practice as clinical herbalist, I have known clients who had problems while taking St. John's Wort or kava kava in combination with Prozac or Zyban, and the American Journal of Natural Medicine has recently announced that a potential potentiation interaction exists between St. John's Wort and antidepressants that enhance serotonin levels. Combinations of St. John's Wort and SSRIs have been linked to serotonin syndrome, a disease caused by excessive serotonin, which results in a constellation of symptoms. Serotonin syndrome usually occurs when two or more serotoninergic drugs (SSRIs) or serotomimetic drugs (eg, dextromethorphan or meperidine are taken concurrently by a patient. Characteristic symptoms include changes in mental condition and behaviour (disorientation, confusion, restlessness, agitation), motor system changes (myoclonus, tremor, rigidity, hyperreflexia, incoordination), and autonomic nervous system instability (fever, diaphoresis, shivering, tachycardia, tachypnea, pupillary dilatation, diarrhoea). Severe cases are potentially fatal, and include such symptoms as fever, nystagmus, dysarthria, opisthotonos, seizures, disseminated intravascular coagulation, rhabdomyolysis, renal failure, cardiac arrhythmias, and coma. The transition from an SSRI to St. John's Wort, then, should be made under medical supervision. The SSRI dosage should be reduced gradually, with only a low dose of St. John's Wort at first. As the dosage of the SSRI is reduced, more St. John's Wort can be administered, ensuring that the total serotonin load is never excessive. An alternative is to taper off the dosage of SSRI completely, and then start to gradually build towards a full dosage of St. John's Wort. This approach, however, leaves the patient unmedicated for a short period of time; depending upon the patient, this may be more dangerous than a potential interaction risk. In neither case should high dosages of SSRI and St. John's Wort be combined. St. John's Wort should also not be combined with 5-HTP (5-hydroxytryptamine), the newest "hot" amino acid supplement, currently sold as a sleeping aid. 5-HTP is always converted to serotonin, and practitioners have seen serotonin syndrome interactions between St. John's Wort and even low doses of 5-HTP. 5-HTP is advertised as having no side effects, but its potential for interaction with other medicines should be considered carefully. Serotonin syndrome can be a very serious condition, and can lead to heart valve problems. 5-HTP is popularly
recommended as a replacement for L-Tryptophan, which was removed from
most markets after a contaminated batch caused serious health problems.
L-Tryptophan is actually "safer" than 5-HTP, because not all
of it is converted to serotonin. Nevertheless, it too can cause serotonin
syndrome when taken together with SSRIs or St. John's Wort, so the combination
should be avoided.
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