Hi, Thanks for posting in HCM. I understand your concern. IMPLANON is a hormone-releasing birth control implant for use by women to prevent pregnancy for up to 3 years. The implant slowly releases etonogestrel into the body over a 3-year period. When you are on such birth control implants, most common side effect experienced is a change in your menstrual bleeding pattern - Your periods may be early or late, shorter or longer, heavier or lighter than normal. Also, you might have spotting between periods. Such symptoms happens especially during the first few months of its use. Gradually, these symptoms should subside or might happen occasionally. If the bleeding is prolonged for more than 8 days or unusually heavy, you need seek medical attention at the earliest. Hope the information provided would be helpful. All the best.