Hard to say, I am not a doctor. But I would imagine that he/she would take you off the medication right away and give you something to clear the rash up. Once the lamictal is out of your system the rash should go away with no problems. There is one potential fatal rash you can develop, Stevens- Johnsons Syndrome, but that is rare. Important thing is if you are taking lamictal and develop a rash at anytime call your pdoc right away. Even if you have been on the medication for a long time, the rash can develop at ANY time that you are taking the medication. It is rare to develop the rash after the first few weeks of taking the mediation, but it can still happen. So, if you develop a rash alwasy check with your pdoc, it could be unrelated but then again it could not be. Always err on the side of caution.