It's not so much an interaction with the Lamictal as it is that hormones are a no-no in bipolar disorder as they can trigger mania. I have gone back and forth about this with people at work. Essentially the docs are divided. Some avoid it in favor of the Paragard b/c of the risk with the hormone, others say it's a small amount and can't possibly have much of an effect. (FYI... Paragard can cause more cramping in the beginning than the Mirena... but know that you can remove the Paragard before the 10 year mark.. you could put it in one day and take it out the next without an issue). In the practice where I worked, we did not use it in people with a history of bipolar disorder but know that if you get it and have a problem then it can always be removed (but who wants to voluntarily cause a bipolar cycle). I would discuss with your pdoc and with your OB/GYN and see if they can talk or what they think and then go from there. I knoe people with bipolar disorder have the Mirena and have no trouble at all, but there is always that chance. Good luck and hopefully whatever you decide it will be fine.