MajorEstrogens. Natural and semisynthetic estrogens, plain×Antidepressants. Other antidepressants of herbal origin
Updated · Methodology
Mechanism
St. John's wort is a potent inducer of the CYP3A4 enzyme (and of CYP2C9 and P-glycoprotein). After 1–2 weeks it speeds up the breakdown of Ethinylestradiol and lowers its blood level, weakening its effect.
Symptoms
Faster breakdown of estrogen and progestin, breakthrough bleeding, reduced contraceptive protection and risk of unintended pregnancy.
Management
Do not combine with oral contraceptives. While taking St. John's wort use a barrier method or another reliable form of contraception.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
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Sources
- British Journal of Pharmacology: Clinical relevance of St. John's wort drug interactions revisited (2020)– Nicolussi S, et al. Br J Pharmacol. 2020;177(6):1212-1226.