Changes in menstrual flow, including the presence of blood clots, can occur when using hormonal contraceptives like the patch. It is not uncommon for this to happen, as hormonal changes can affect your menstrual cycle. If you find that your bleeding is too heavy when you stop using the patch, you can try taking a shorter break to reduce the duration of your period. If bleeding occurs outside of your break period, it could indicate that the contraceptive may not be strong enough for you. In this case, it may be helpful to speak with a pharmacist about other options available to you.