How the interaction occurs:
When these two medicines are taken together, your body processes estrogens more quickly.
What might happen:
A decrease in the beneficial effects of your estrogens may occur. Your risk for osteoporosis may increase.
What you should do about this interaction:
If you experience spotting, breakthrough bleeding, or vaginal pain, contact your doctor. It may be necessary to increase the dose of your medicine.Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this drug interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.Janz D, Schmidt D. Letter: Anti-epileptic drugs and failure of oral contraceptives. Lancet 1974 Jun 1;1(7866):1113.
2.Laengner H, Detering K. Letter: Anti-epileptic drugs and failure of oral contraceptives. Lancet 1974 Sep 7;2(7880):600.
3.Hempel E, Klinger W. Drug stimulated biotransformation of hormonal steroid contraceptives: clinical implications. Drugs 1976 Dec;12(6):442-8.
4.Roberton YR, Johnson ES. Interactions between oral contraceptives and other drugs: a review. Curr Med Res Opin 1976;3(9):647-61.
5.Coulam CB, Annegers JF. Do anticonvulsants reduce the efficacy of oral contraceptives?. Epilepsia 1979 Oct;20(5):519-25.
6.Back DJ, Bates M, Bowden A, Breckenridge AM, Hall MJ, Jones H, MacIver M, Orme M, Perucca E, Richens A, Rowe PH, Smith E. The interaction of phenobarbital and other anticonvulsants with oral contraceptive steroid therapy. Contraception 1980 Nov;22(5):495-503.
7.Anonymous. Drug interaction with oral contraceptive steroids. Br Med J 1980 Jul 12;281(6233):93-4.
8.Mattson RH, Cramer JA, Darney PD, Naftolin F. Use of oral contraceptives by women with epilepsy. JAMA 1986 Jul 11;256(2):238-40.