Bleeding while on birth control is commonly due to breakthrough bleeding or withdrawal bleeding. Breakthrough bleeding can happen with any hormonal birth control method because the hormones (estrogen and progestin) cause the uterine lining to temporarily thin and become unstable, leading to spotting or bleeding between periods. It is especially frequent in the first few months after starting birth control as the body adjusts to the hormones. Missing pills, changing birth control types, or taking low-dose pills can also trigger such bleeding. Withdrawal bleeding, which is like a lighter period, occurs during the hormone-free days in the pill cycle or when hormone levels drop due to missed pills or switching birth control types. These bleedings are generally not harmful but should be monitored. If bleeding is very heavy, prolonged, or accompanied by other symptoms, consulting a healthcare provider is advised.
