Is there a scientific/chemical explanation as to why Saint John's Wort is said to interfere with birth control

Question

I know that there is anecdotal evidence that SJW can decrease the effectiveness of oral contraceptives, but is there any solid evidence or proof that it is actually the culprit in these incidences rather than there being another possible cause? If so, what is the chemical action that causes the interference? Also, is anyone aware of how greatly the oral contraceptive effect is decreased? Please HELP, because I want to try taking SJW as I can't afford anymore prescription antidepressants, but I can also not afford to get pregnant. Do I really need to worry or is the connection unproven? Thank you...

Answer 1

Saint John's Wort is a Metabolic inducer of the CYP450 liver enzymes. What happens in lay-mans terms is: SJW speeds up the metabolism of your birth control. I know this isn't exactly accurate but it's the easiest way to explain......for example your birth control pill is designed to work for 24 hours. When taken with saint john's wort it speeds up the metabolism. your birth control gets into your system faster and leaves your system faster. So now your birth control pill only works for say 12 hours. Again not exact times there but you get the idea. Saint john's wort affects a lot of drugs this way. I personally wouldn't take it if I were on any important medications such as that. There have been documented cases of women getting pregnant while on B/C and SJW. By the way there are some antidepressant medications on the $4.00 list at wal-mart if your state's wal-mart is doing that. I know NC and Fl have the $4.00 prescriptions.

Answer 2

i wouldn't mix st john's wort and oral contraceptives. I had a pharmacology professor talk about it might have something to do with St. john's inducing an enzyme that increases metabolism of birth control and some other drugs.
Also I would ask a doctor how soon after stopping presciption antidepressants you have to wait before starting st. johns because st johns i think elevates serotonin, as do many antidepressants and there is something called serotonin syndrome.

I looked just now and found this abstract:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=14663455&query_hl=3&itool=pubmed_docsum

Answer 3

I searched in Pubmed central which is the place all peer review real scientific journals appear. And couldnt find any journal which was saying Saint John's Wort interfered with birth control.
One of the herbal pages said that there was no scientific proof that it interfered with birthcontrol.
http://www.herbs.org/greenpapers/stjohnswort.htm