Medicine Reaction, Irregular Periods

Many prescription and nonprescription medicines can affect the menstrual cycle. A few examples are:

• Aspirin and other medicines (called blood thinners) that prevent blood clots.
• Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (for example, Advil or Motrin) and naproxen (for example, Aleve).
• Hormonal forms of birth control, such as birth control pills, Depo-Provera injections, Implanon or Nexplanon implants, and the levonorgestrel IUD (Mirena).
• Hormone therapy.
• Medicines used to treat cancer (chemotherapy).
• Thyroid medicines.