Hello, and I hope I can help you today. Vyvanse is a stimulant medication that works completely outside of your hormonal system. Therefore, there is no interaction between this medication and your Quasence. However, some women after being on three month cycle pills start to have breakthrough bleeding before the three months are completed, especially if they have taken birth control for a long time. In simple terms, your body can build up a tolerance to the ability of the pill to control your menstrual cycle. It does not mean that the pill does not work for contraception, it is just caused by your uterine lining being very thin from the low dose of estrogen in the pill over time. There is also a possibility that, if you missed a pill or even took it late at some point in the second pack, that can also trigger breakthrough bleeding. I would just finish this pack of pills and see what happens next pack to see if the spotting is a recurrent problem. If you regularly start to spot in the second month, when the bleeding gets too annoying for you, just stop the pill and do the placebo pills in the second month. Then restart the pack and go right to the new one. See how many weeks you can go without bleeding and then once you start bleeding do the same thing again. Even if you can extend your cycle for two months it is still better than a period every month. As long as you do not go longer than 7 days between the active pills in the pack, you will be protected against pregnancy. I hope I was able to answer your question and that my advice was helpful. Best wishes, Dr. Brown