Is it normal to get throbbing headaches when you stand up after sitting for a long time?

Throbbing Headache!!: No. The simple answer is no. Thus this symptom or repeated episodes of pain need to be investigated. I would look at blood pressure, other concurrent symptoms, fever, dehydration, blood sugars and these common clues to point to the cause of your troubles. But, you do not need to continue to suffer. Please get to a good health care provider and find a root cause for your troubles.