The pill's own label names it among things that can weaken it
A widely used low-dose combined contraceptive lists St John's Wort among products that can make hormonal contraception less effective or cause breakthrough bleeding.
What the study found
The pill's own label names it, in the section written for patients
A widely used low-dose combined contraceptive lists St John's Wort among ten products that can make hormonal contraception less effective or cause breakthrough bleeding. It says so in the plain-language patient section too, and tells users to consider a second method.
The caveat · Names the risk, never its size
The label states the risk without giving it a size, and puts St John's Wort in the same list as rifampin, a far more powerful enzyme inducer, without ranking them. It covers one product; wording across other combined pills is similar but not identical, and progestogen-only methods are not covered at all.