Lamictal (lamotrigine) is a mood stabiliser which is effective in bipolar disorder. It is especially useful in those with long years or decades of illness because they are now more prone to depressive episodes than manic episodes. Your doctor must have prescribed Thorazine (chlorpromazine) because of one of several reasons: 1) Sleep disturbance in case you have been having difficulty in recent weeks due to any stress. Sleep deprivation can precipitate further episodes of bipolar disorder and hence the medication. 2) You may have had hypomanic or manic symptoms (an early relapse) in recent weeks. The side-effects you have mentioned are dose related and may not occur to you at low doses that have been prescribed. You may consult your doctor in case you experience any of these side-effects with the drug and there are other alternate medications. Weight gain, however, is a side-effect with many of these medications. You will have to include regular exercise (to the extent permitted by your physician) and have diet modification (include more fruits, vegetables and fiber; reduce meat and fats & oils) to prevent weight gain.