Posted by Larry Hoover on November 25, 2002, at 10:15:39
In reply to Re: St Johns Wort Works!, posted by Alara on November 25, 2002, at 3:26:26
> Thanks, Axtabelle. My mood is actually a little brighter when I am off the pill, but everybody is different and I'm glad that it is helping you. At the end of the day I really don't mind taking the pill - as long as I know it's working!
> Does anybody have links to studies supporting the claim that St John's Wort reduces the efficacy of the pill? So far I have found many vague statements such as "St John's Wort can reduce the efficacy of the pill by 50%." None of the claims that I have read have been backed up by evidence. Has anyone sighted a relevant study?
SJW is believed to increase the activity of the enzyme known as CYP3A4. The evidence is pretty strong for that, although circumstantial. That's the same enzyme which the body uses to process the synthetic hormones in oral contraceptives.
There are only case reports in the literature of breakthrough bleeding and unwanted pregnancy, usually in the form of letters to the editor of medical journals, rather than studies per se. Considering the widespread use of SJW and oral contraceptives, the risk appears to be small (or under-reported). The pill is not fool-proof to begin with, so you have to assess the risk in the context of your own life, i.e. how much risk of pregnancy are you willing to accept? If you can't risk pregnancy, use a back-up method.