II. Drug Interactions: Drugs decreasing Oral Contraceptive efficacy

  1. See Antiepileptic Drug Interactions in Contraception
  2. Enzyme Inducing Drugs (e.g. Rifampin, Rifapentine, rifabutin) signicantly reduce OCP efficacy
    1. Use backup Contraception
    2. Barrier methods or Depo Provera if <2 months of enzyme inducing drug
    3. Depo Provera or Progesterone IUD if >2 months of enzyme inducing drug
    4. (2015) Presc Lett 22(6): 31-2
  3. Other medications reduce OCP efficacy less
    1. Amoxicillin
    2. Ampicillin
    3. Erythromycin
    4. Fluconazole (Diflucan)
    5. Griseofulvin
    6. Itraconazole (Sporanox)
    7. Ketoconazole (Nizoral)
    8. Metronidazole (Flagyl)
    9. Ritonavir
    10. St. John's Wort (results in breakthrough bleeding)
    11. Tetracycline
    12. Troglitazone (Rezulin)

III. Drug Interactions: Drugs with decreased efficacy when taken with OCP

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