The new warning comes from the U.K.’s drug enforcers — the Medicines and Healthcare Products Regulatory Agency (MHRA). The warning specifically relates to women taking emergency contraceptive pills that have the active ingredient levonorgestrel.
The advice recommends that women taking remedies containing St John’s Wort should double the dose of levonorgestrel. St John’s Wort is scientifically known as Hypericum perforatum. It is a flowering plant that has some antidepressant activity, although this is not supported by all psychiatrists. For example, the U.S. National Institutes of Health, has said it “may help some types of depression, though the evidence is not definitive.” The herb also possess potent anti-inflammatory properties.
The common name “St John’s wort” comes from its traditional flowering and harvesting on St John’s Day, which is June 24. In medieval times the plant was thought to ward off evil.
Irrespective of the plant’s history or medical benefits one thing the ingredients can do is interfere with prescribed medications. Most notably this is with levonorgestrel, which is a hormonal type of emergency contraception typically used within three days of unprotected sex to prevent unwanted pregnancies. The pill is sold under the brand name Plan B.
Speaking with the BBC, Dr Sarah Branch, who is the deputy director of MHRA’s Vigilance and Risk Management of Medicines Division, stated: “Our new patient information sheet provides information on what types of medicines could interfere with how the emergency contraceptive works.”
