Effects of Caffeine on Analgesia from Transcutaneous Electrical Nerve Stimulation

Abstract

To the Editor: The mechanism of the analgesia resulting from transcutaneous electrical nerve stimulation (TENS) is not clear. A possible mediator of TENS analgesia is adenosine, formed from adenosine triphosphate released from the large primary afferent fibers that are selectively recruited by TENS.1,2 Moreover, the inhibitory effect of vibration, which also activates these afferents, on nociceptive neurons in the spinal cord is blocked by the adenosine-receptor antagonist caffeine.1 Using a double-blind protocol, we investigated the effect of 200 mg of caffeine and 200 mg of placebo, given orally in random order one week apart, on the perception of intensity. © 1995, Massachusetts Medical Society. All rights reserved.