Is it safe to suck on a lollypop while giving blood?

im afraid of needles but i really want to give blood because of my rare blood type, im finally old enough to do it. i always suck on lollypops when im stressed out, and even when i was small ad i thought that cutting your hair hurt i did it. im just wondoring if the sucking motion in the mouth changes the blood pumping because of the suction?