Andi mentioned high blood pressure - I'd like to add that it could also be low blood pressure. My blood pressure is normally low, and sometimes when I flare it seems to drop even lower to the point where I get dizzy and light-headed. For me, I tend to lose sodium easily especially when I'm having diarrhea, and that seems to be tied to my blood pressure, so when I feel that way I eat something salty and then I feel much better. Give that a try and see if it helps. And I agree 100% with Crabby, please go to your doctor ASAP so they can find the cause of your dizziness and get you some relief!