St. John's wort can reduce the effectiveness of which contraception method?

• A. IUD
• B. Oral contraceptives
• C. Transdermal patch
• D. Condom

Answer: (B)

St. John’s wort can cause the body to ramp up liver enzymes that break down many drugs, especially the CYP3A4 pathway and P-glycoprotein. When these enzymes are induced, the hormones in oral contraceptives (estrogen and progestin) are metabolized faster, lowering their blood levels and reducing how well they prevent pregnancy. That’s why this herb is known to reduce the effectiveness of oral contraception.

Barrier methods like condoms act by a physical barrier and aren’t affected by liver metabolism, and copper IUDs are non-hormonal, so they aren’t tied to hormone levels in the same way. Hormonal implants or injections deliver hormones differently, but the most consistently impacted method in reported interactions is oral contraception, hence the emphasis on this combination.

If you’re using St. John’s wort, talk with a healthcare provider about contraception options or avoiding the herb while on hormonal birth control. Consider non-hormonal methods or barrier methods, or switching to a non-inducing regimen under medical guidance.