"i switched from generic immediate release lamotrigine to lamictal xr about a week ago. in the last week i have had the unfortunate and horrible side effect of diarrhea. the worst i have ever experienced; it would start a few hours after taking my meds (at bedtime...) and last until about noon the following day. it took me about a week to realize it was related to the medication change. when i stopped taking the medication the diarrhea went away. i&#039;ve seen tons of positive reviews about the xr, but it just wasn&#039;t for me. i gave it a 3 because it still stabilized my mood while i was on it."