Routine blood draws are done in the morning on an empty stomach, requiring a normal meal the night before and no eating or drinking after 10 o’clock. If the routine test is done after eating, it may affect the results of the blood draw, such as liver function, kidney function and blood sugar. If the blood is drawn in the afternoon, it is usually an emergency blood draw. Of course, it is also recommended that you should not eat before the blood draw, because eating may cause blood sickness or other conditions during the blood draw, which may lead to nausea and vomiting. Emergency blood draws are needed on an emergency basis, such as when there is abdominal pain or other illnesses that require blood draws.