Final answer:
The appropriate action to take if a patient begins to seize during a venipuncture is to discontinue the draw.
Step-by-step explanation:
In the scenario where a patient begins to seize while a phlebotomist is performing a venipuncture, the appropriate action to take is to discontinue the draw. It is crucial to ensure the safety and well-being of the patient during a seizure, and continuing with the procedure can pose significant risks. The phlebotomist should prioritize the patient's health and wait until the seizure has subsided before continuing with the venipuncture or seek medical assistance if necessary.