Terry- The term used to describe the lightheadedness and fainting caused by low blood pressure when standing from a sitting position is called orthostatic hypotension. I recommend to all patients taking Sinemet that when they are standing from a sitting or lying position to take it very slow so that yourbody can become adjusted to the effects of gravity on blood and oxygen reaching the brain. Dominic Marchese, RPh. Athena Rx Home Pharmacy 1-800-5-ATHENA