Vitamin C supplements and birth control effectiveness?

Dear Alice,

Is it true that taking those Emergen-C packets or any other vitamin supplements can effect the effectiveness of your birth control pill?

Dear Reader,

Emergen-C packets and other vitamin supplement drinks have become popular recently because they provide vitamin C, which is an essential nutrient, and they taste pretty good! However, research is inconclusive on whether such large doses of vitamin C are necessary and how these doses interact with other medications — birth control included.

Emergen-C packets may be a good way to make sure you are getting the necessary vitamin C, but they contain very high doses; if you take the recommended two to four packets per day you could get more than 4000 times what your body needs! Too much of anything, even a healthy vitamin, might not be a good idea.

Very high doses of vitamins may interfere with the birth control pill, though research is limited in this area. Known interactions and reduced efficiency occur with St. John's wort, an herbal supplement, but vitamins A, C, and potassium may also have effects. The pill has also been has been associated with some vitamin deficiencies, most commonly B6, B12, C and folic acid, which is why some people are encouraged to take vitamin supplements or watch their dietary intake more carefully when taking birth control pills. An added bonus is that getting enough of B6 and B12 may help alleviate some side effects of the pill such as nausea and mood swings. Talking with a health care professional will help you manage vitamin intake without compromising the effectiveness of your birth control.

If you're still not feeling clear on how vitamins interact with the pill, it's not you; research in this area is inconclusive. In a nutshell, some vitamins and the birth control pill seem to interact, however vitamins in small doses will likely not influence the effectiveness of the pill. It's always a good idea, though, to have a conversation with your health care provider and give the clearest possible picture.

Remember, vitamins are vital, but too much of a good thing isn't always better.

Last updated May 21, 2015
Originally published May 23, 2008

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