Hello, and I hope I can help you today. Generic medications have the same active ingredients as the brand name drug, but the ingredients in the pill that give it it s color and shape can affect how your body digests the pill and can sometimes give you different side effects. I have seen many patients who have new side effects when changing from a brand name to a generic, or substituting one generic for another. The breakthrough bleeding with Lessina may improve over time, but if you are feeling lightheaded and dizzy you should call your healthcare provider and have an examination to check for anemia or any other reasons you feel lightheaded. Unless you are bleeding very heavily (changing a soaked pad every hour) it is unliklely you have lost enough blood to become symptomatic from 6 days of brekthrough bleeding, so a medical evaluation really needs to be done for your light-headedness. In the meantime, i would also contact the doctor who prescribed you the Lessina and see if you could be changed to a pill with a slightly higher dose of estrogen. The amount of estrogen is what helps to control your menstrual cycle on the pill, and you may benefit temporarily for a change in brand. Also, if your local pharmacy doesn t stock Aviane, another pharmacy in your area may have it and changing pharmacies may help you to get more of the brand that works best for you. I hope i was able to answer your questions today and that my advice was helpful. Best wishes, Dr. Brown