Mechanisms of "Cough-Trick" for Pain Relief during Venipuncture: An Experimental Crossover Investigation in Healthy Volunteers.

Pain-reducing effect of CT during VP is superior to that of simple motor distraction and equivalent to a complex distraction method. This might be due to the activation of segmental pain inhibitory pathways during coughing indicated through the lack of pain reduction due to CT under opioid antagonist blockage.