St. John's wort セントジョーンズワート（セイヨウオトギリソウ）

In Japan

• In Japan, it is an ingredient that is "not judged to be a drug unless it makes drug-like efficacy claims," and it is sold as a so-called health food.
• MHLW has issued a caution that it strengthens liver enzymes that break down drugs (CYP3A4 and CYP1A2), which may lower the blood levels of drugs taken together with it and weaken their effect (Pharmaceuticals and Medical Devices Safety Information No. 160). Examples of affected drugs are anti-HIV drugs, warfarin, immunosuppressants (cyclosporine and tacrolimus), oral contraceptives, digoxin, theophylline, antiepileptic drugs, and antiarrhythmic drugs.
• Products are instructed to state "contains St. John's wort (Hypericum perforatum)" and to advise people who are taking medication to refrain from using it.

In the EU: the register of health claims

No claim in the EU register

• No claim for this ingredient is listed in the EU health claims register. In the EU, the evaluation of many botanical claims (about 2,000) remains on hold, and those are not listed in the register.

In the EU, only health claims whose evidence has been assessed by the European Food Safety Authority (EFSA) and authorised by the European Commission may be used on food. “Not authorised” means the evidence for that claim was not established under EU standards — not that the ingredient is dangerous.

What the US NIH says

• Some studies found it as effective as standard antidepressants for mild to moderate depression. For other purposes the evidence is insufficient.
• It has been clearly shown to cause dangerous interactions, sometimes life-threatening, with a variety of drugs (antidepressants, oral contraceptives, cyclosporine, warfarin, some statins, and others).

Sources: NCCIH "St. John's Wort"