Which herbal supplement is known to interfere with the efficacy of oral contraceptives?

St. John's Wort is known for its ability to affect the metabolism of certain medications, including oral contraceptives. This herbal supplement contains compounds that induce certain enzymes in the liver, particularly CYP3A4, which is responsible for the breakdown of many drugs. When taken alongside oral contraceptives, St. John's Wort can increase the metabolism of the contraceptive hormones, potentially leading to reduced effectiveness and a higher risk of unintended pregnancy.

In contrast, the other herbal supplements listed do not have this significant impact on the efficacy of oral contraceptives. Ginseng, Echinacea, and Chamomile are not known to induce the same liver enzymes that St. John's Wort does, making them unlikely to interfere with hormone-based contraceptive methods. Therefore, understanding the interactions of St. John's Wort is crucial for individuals using oral contraceptives to ensure they maintain adequate contraceptive protection.