Oral Contraceptives

Also indexed as: Alesse-28®, Alesse®, BiNovum®, Brevicon®, Brevinor®, Cilest®, Cyclen®, Demulen®, Desogen®, Desogestrel, Ethynodiol, Eugynon®, Femodene®, Genora®, Jenest®, Levlen®, Levonorgestrel, Lo/Ovral®, Loestrin®, Logynon®, Marvelon®, Mercilon®, Mestranol, Microgynon®, Micronor®, Min-Ovral®, Minestrin®, Minulet®, Modicon®, Necon 1/35®, Necon®, Nelova®, Nordette®, Norethindrone, Norethin®, Norgestrol, Norimin®, Norinyl-I®, Norinyl®, Ortho Tri-Cyclen®, Ortho-Cept®, Ortho-Cyclen®, Ortho-Novum®, Ortho®, Ovcon®, Ovral®, Ovranette®, Ovran®, Ovrette®, Ovysmen®, Select®, Synphase®, Synphasic®, Tri-Cyclen®, Tri-Minulet®, Tri-Norinyl®, Triadene®, Trinordiol®, TriNovum®, Triphasil®, Triquilar®

Oral contraceptives, or birth control pills, are primarily used to prevent pregnancy and to treat menstrual irregularities and endometriosis. Oral contraceptives are available as an oestrogen and progestin combination or as a progestin-only product. The oestrogens used in oral contraceptives are different from those used in hormone-replacement therapy. Consequently, interactions involving oestrogens used in birth control pills may or may not be similar to those used in hormone replacement.

Interactions that are common to oral contraceptives are described below. For interactions involving drugs used in hormone-replacement therapy, refer to the article on oestrogen.

Mestranol and Norethindrone

Genora 1/50®
Nelova 1/50®
Norethin 1/50®
Ortho-Novum 1/50®

Ethinyl estradiol and Norethindrone

Brevicon®
Estrostep®
Genora 1/35®
GenCept 1/35®
Jenest-28®
Loestrin 1.5/30®
Loestrin1/20®
Modicon®
Necon 1/25®
Necon 10/11®
Necon 0.5/30®
Necon 1/50®
Nelova 1/35®
Nelova 10/11 ®
Norinyl 1/35®
Norlestin 1/50®
Ortho Novum 1/35®
Ortho Novum 10/11®
Ortho Novum 7/7/7®
Ovcon-35®
Ovcon-50®
Tri-Norinyl®

Ethinyl estradiol and Ethynodiol

Demulen 1/35®
Demulen 1/50®
Nelulen 1/25®
Nelulen 1/50®
Zovia®

Ethinyl estradiol and Norgestrel

Lo/Ovral®
Ovral®

Ethinyl estradiol and Levonorgestrel

Alesse®
Levlen®
Levlite®
Levora 0.15/30®
Nordette®
Preven® Emergency Contraceptive Kit
Tri-Levlen®
Triphasil®
Trivora®

Ethinyl estradiol and Desogestrel

Desogen®
Ortho-TriCyclen®

Levonorgestrel

Plan B®
Norethindrone
Micronor®
Nor-QD®
Norgestrel
Ovrette®

Summary of Interactions with Vitamins, Herbs, and Foods
In some cases, a herb or supplement may appear in more than one category, which may seem contradictory. For clarification, read the full article for details about the summarized interactions.

May be Beneficial: Depletion or interference—The medication may deplete or interfere with the absorption or function of the nutrient. Taking these nutrients may help replenish them.	Folic acid Magnesium* Vitamin B1* Vitamin B12* Vitamin B2* Vitamin B3* Vitamin B6 Vitamin C* Zinc*
May be Beneficial: Side effect reduction/prevention—Taking these supplements may help reduce the likelihood and/or severity of a potential side effect caused by the medication.	Folic acid Vitamin B6
May be Beneficial: Supportive interaction—Taking these supplements may support or otherwise help your medication work better.	Folic acid*
Avoid: Adverse interaction—Avoid these supplements when taking this medication because taking them together may cause undesirable or dangerous results.	St. John’s wort* Tobacco
Check: Other—Before taking any of these supplements or eating any of these foods with your medication, read this article in full for details.	Calcium Copper Iron Manganese Vitamin A
Reduced drug absorption/bioavailability	None known
Interactions common to many, if not all, Oral Contraceptives are described in this article. Interactions reported for only one or several drugs in this class may not be listed in this article. Some drugs listed in this article are linked to articles specific to that respective drug; please refer to those individual drug articles. The information in this article may not necessarily apply to drugs in this class for which no separate article exists. If you are taking an Oral Contraceptive for which no separate article exists, talk with your doctor or chemist.

An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.

Interactions with Dietary Supplements

Folic acid
Oral contraceptive (OC) use can cause folic acid depletion.¹ In a double-blind trial of OC users with cervical dysplasia, supplementation with very large amounts (10 mg per day) of folic acid improved cervical health.² Women with cervical dysplasia diagnosed while they are taking OCs should consult a doctor. Mega-folate supplementation should not be attempted without a doctor’s supervision, nor is there any reason to believe that folic acid supplementation would help people with cervical cancer.

Iron
Menstrual blood loss is typically reduced with use of OCs. This can lead to increased iron stores and, presumably, a decreased need for iron in premenopausal women.³ Premenopausal women taking OCs should have their iron levels monitored and talk with their prescribing doctor before using iron-containing supplements.

Magnesium
Women using OCs were found to have significantly lower serum magnesium levels in a controlled study.⁴ In a preliminary study, blood levels of magnesium decreased in women taking an OC containing ethinyl estradiol and levonorgestrel.⁵ Although the importance of this interaction remains somewhat unclear, supplementation with 250–350 mg of magnesium per day is a safe and reasonable supplemental level for most adults.

Vitamin B6
Oral contraceptives have been associated with vitamin B6 depletion and clinical depression. In a small, double-blind study of women with depression taking OCs, vitamin B6 (20 mg twice per day) improved depression.⁶ Half of the women in the study showed laboratory evidence of vitamin B6 deficiency.

Other nutrients
A review of literature suggests that women who use OCs may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.⁷ ⁸ ⁹ OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.¹⁰ ¹¹ ¹² OCs may interfere with manganese absorption.¹³ The clinical importance of these actions remains unclear.

Interactions with Herbs

St. John’s wort
Eight cases reported to the Medical Products Agency of Sweden suggest that St. John’s wort may interact with oral contraceptives and cause intramenstrual bleeding and/or changes in menstrual bleeding.¹⁴ One reviewer has suggested that St. John’s wort may reduce serum levels of estradiol.¹⁵ It should be noted, however, that only three of the eight Swedish women returned to normal menstrual cycles after stopping St. John’s wort. Women taking oral contraceptives for birth control should consult with their doctor before taking St. John’s wort.

Interactions with Foods and Other Compounds

Tobacco (Nicotiana species)
Women who smoke and use OCs have a five-times greater risk of dying from a heart attack than OC users who do not smoke.¹⁶ Women over the age of 35 who smoke and use OCs have a greatly increased risk of death related to circulatory disease.¹⁷ Avoiding or giving up smoking is good for health.

References
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1. Lindenbaum J, Whitehead N, Reyner F. Oral contraceptive hormones, folate metabolism, and the cervical epithelium. Am J Clin Nutr 1975;28:346–53.

2. Butterworth CE Jr, Hatch KD, Gore H, et al. Improvement in cervical dysplasia associated with folic acid therapy in users of oral contraceptives. Am J Clin Nutr 1982 ;35:73–82.

3. Frassinelli-Gunderson EP, Margen S, Brown JR. Iron stores in users of oral contraceptive agents. Am J Clin Nutr 1985;41(4):703.

4. Olatunbosum DA, Adeniyi FA, Adadevoh BK. Effect of oral contraceptives on serum magnesium levels. Int J Fertil 1974;19:224–6.

5. Blum M, Kitai E, Ariel Y, et al. Oral contraceptive lowers serum magnesium. Harefuah 1991;121:363–4 [in Hebrew].

6. Adams PW, Wynn V, Rose DP, et al. Effect of pyridoxine hydrochloride (vitamin B6) upon depression associated with oral contraception. Lancet 1973;I:897–904.

7. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

8. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

9. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197–8.

10. Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210–1 [review].

11. Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561–4.

12. Berg G, Kohlmeier L, Brenner H. Effect of oral contraceptive progestins on serum copper concentration. Eur J Clin Nutr 1998;52:711–5.

13. Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.

14. Safety of St. John’s wort (Hypericum perforatum) [letters to the editor from various authors]. Lancet 2000;355:575–7.

15. Ernst E. Second thoughts about safety of St. John’s wort [letter]. Lancet 1999;354:2014–6.

16. Threlkeld DS, ed. Hormones, Oral Contraceptives. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Jul 1994, 107b–8f.

17. Threlkeld DS, ed. Hormones, Oral Contraceptives. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Jul 1994, 107b–8f.

Please read the disclaimer about the limitations of the information provided here. Do NOT rely solely on the information in this article.

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Learn more about the authors of Using Medicines with Vitamins and Herbs

The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires March 2007.

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