--whether used for the relief of neuropathic pain or not, seem, with the exception of Topomax (and nobody seems to quite know why with that one) to have, as a common side effect, weight gain, either through fluid retention, carb craving, or both.

As Mrs. D notes, not all people expereince this, and there does seem to be at least some dose dependency. But it happens often enough that people taking them are well advised to pay close attention to their nutrition--and hey, we'd probably all be healthier eating fewer carbs anyway.