Supplements and Birth Control and Hormone Medicines

Safety box: possible unplanned pregnancy

For hormonal birth control, the concern is not a side effect but a method that may work less well. A 2009 review of clinical observations lists "unwanted pregnancies in women while using oral contraceptives and SJW" among well-documented St. John's wort interactions. [1] If you use hormonal contraception and take, or are thinking of taking, St. John's wort, ask the prescriber or pharmacist what that means for your method before relying on it. Do not stop a prescribed medicine on your own.

The question

Can herbs and supplements make hormonal birth control or menopause hormone therapy less effective? One herb, St. John's wort (Hypericum perforatum), has real evidence. For most other products, the honest answer is that interactions were not studied.

Combined birth control pills

• Systematic review. A 2016 systematic review in Contraception found four studies that compared combined oral contraceptives with and without St. John's wort. [2] Three studies showed more breakthrough bleeding, and one showed more follicle growth and probable ovulation. [2] The authors concluded that this limited evidence raises concern for reduced contraceptive effectiveness, and that the blood-level evidence was mixed. [2] Label: documented but limited, from small studies.
• NCCIH lists birth control pills among the medicines St. John's wort can affect. [3]
• MedlinePlus names St. John's wort as a herbal product that may interact with ethinyl estradiol and norethindrone pills. [4]
• NHS (UK) says St John's wort can interact with the contraceptive pill, reducing its effectiveness. [5]

Contraceptive injections

The NHS says not to take St John's wort with medroxyprogesterone contraceptive injections because it can affect the way the injection works. [6] It adds that there is not enough information to say other complementary medicines, herbal remedies and supplements are safe to take with it. [6]

Menopause hormone therapy (HRT)

The NHS says St John's wort may stop HRT tablets and capsules from working as well, and that HRT patches will be less affected. [7] It also says it is not possible to say that other herbal remedies and supplements are safe to take with HRT, because they are generally not tested for their effect on other medicines. [7] Label: official guidance. For menopause herbs themselves, see Black Cohosh, Soy, Red Clover and "Hormone Balance" Claims and Menopausal Hormone Therapy and Aging.

What is not known

Proper evidence not found, in the sources read for this page, for interactions between hormonal contraceptives and herbs other than St. John's wort, or for vitamins and minerals. We searched PubMed, NHS and MedlinePlus pages. That is not a finding of safety. Also, we did not read a source giving how long an effect lasts after St. John's wort is stopped, so we do not state one.

What a reader can do

• Tell the prescriber or pharmacist about all herbs and supplements when starting or changing birth control or hormone therapy.
• Ask directly: "Could anything I take make my method less reliable, and what backup do you recommend?"
• Do not stop birth control or hormone therapy because of a supplement. Ask the prescriber.
• More: St. John's Wort Interactions, How Interactions Work and Pregnancy and Breastfeeding.