Drug
Levonorgestrel
Pronounced
"on-DAN-se-tron"
Drug Interactions
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.
Some drugs may cause emergency birth control to work less well by decreasing the amount of birth control hormones in your body. This effect can result in pregnancy. Examples include griseofulvin, modafinil, rifamycins (such as rifampin, rifabutin), St. John's wort, drugs used to treat seizures (such as barbiturates, carbamazepine, felbamate, phenytoin, primidone, topiramate), HIV drugs (such as nelfinavir, nevirapine), among others. Talk to your doctor or pharmacist for more details (see also Uses section).
Negative Interactions
1- Potential Negative Interaction
Levonorgestrel
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. One reviewer has suggested that St. John’s wort may reduce serum levels of estradiol. 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.
St. John’s WortLevonorgestrel- Safety of St. John's wort (Hypericum perforatum) [letters to the editor from various authors]. Lancet 2000;355:575-7.
- Ernst E. Second thoughts about safety of St. John's wort. Lancet 1999;354:2014-6 [letter].
Supportive Interactions
5- Replenish Depleted Nutrients
Levonorgestrel
Folic Acid
Oral contraceptive use can cause folic acid depletion.
Folic AcidLevonorgestrel- Lindenbaum J, Whitehead N, Reyner F. Oral contraceptive hormones, folate metabolism, and the cervical epithelium. Am J Clin Nutr 1975;28:346-53.
- Replenish Depleted Nutrients
Levonorgestrel
Vitamin B1
A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.
Vitamin B1Levonorgestrel- Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].
- Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.
- Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197-8.
- Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.
- Replenish Depleted Nutrients
Levonorgestrel
Vitamin B3 (Niacin)
A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.
Vitamin B3 (Niacin)Levonorgestrel- Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].
- Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.
- Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197-8.
- Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.
- Replenish Depleted Nutrients
Levonorgestrel
Zinc
A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels. Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A. Oral contraceptives may interfere with manganese absorption. The clinical importance of these actions remains unclear.
ZincLevonorgestrel- Werbach MR. Foundations of Nutritional Medicine. Tarzana, CA: Third Line Press, 1997, 210-1 [review].
- Wynn V. Vitamins and oral contraceptive use. Lancet 1975;1:561-4.
- Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197-8.
- Holt GA. Food & Drug Interaction. Chicago: Precept Press, 1998, 197.
- Reduce Side Effects
Levonorgestrel
Folic Acid
In a double-blind trial of oral contraceptive users with cervical dysplasia, supplementation with very large amounts (10 mg per day) of folic acid improved cervical health. Women with cervical dysplasia diagnosed while they are taking oral contraceptives 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.
Folic AcidLevonorgestrel- 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.