Medicines that can cause changes in menstrual bleeding

Changes in menstrual bleeding may be caused by a medicine. For example, it is not uncommon to have some midcycle spotting with low-dose estrogen birth control pills. Other medicines that can cause abnormal, lighter, heavier, less frequent or more frequent bleeding, or skipped periods include:

• Anticoagulant medicines such as aspirin, Coumadin, and nonsteroidal anti-inflammatory drugs (NSAIDs).
• Antipsychotics.
• Seizure medicines, such as Dilantin or Depakote.
• Corticosteroids, such as prednisone.
• Dilantin.
• Hormonal medicines, including:
  • Birth control pills, Depo-Provera injections, and Implanon implants.
  • Contraceptive implants, such as the levonorgestrel intrauterine device (IUD) Mirena.
  • Hormone replacement therapy (HRT).
• Medicines to prevent organ transplant rejection.
• Medicines used to treat cancer (chemotherapy), such as Cytoxan or tamoxifen.
• Radiation therapy.
• Thyroid medicine, such as Synthroid or Levothroid.
• Tricyclic antidepressants.

If you are having changes in menstrual bleeding that you think may be related to medicine use:

• Call the doctor who prescribed the medicine to determine whether this is an expected side effect of this medicine. An appointment may not be needed.
• If you are taking a medicine not prescribed by a doctor, stop taking it. Call your doctor if you feel you need to keep taking the medicine or if you need help to control your symptoms after you stop the medicine.