@115 I only take one Imodium at a time as well. It usually does the trick. I rarely get constipated, but an over the counter stool softener like docusate keeps things moving for me too. I still do occasionally get light headed and at times lose my balanced a little. I find a place to sit as quickly as possible. They usually pass in a few minutes. Tell your doctor about the light headedness and any associated balance issues. That is something he or she needs to know about. How is the radiation treating you?