Pain

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.

Pain begins when specialized nerve endings called nociceptors detect injury, heat, pressure or chemical irritation and send signals through the spinal cord to the brain. The brain then interprets those signals in light of attention, memory, mood and context, which is why the same injury can feel very different from one person or one day to the next. Clinicians usually sort pain by duration, with acute pain lasting days to weeks and chronic pain persisting beyond three months, and by mechanism, distinguishing nociceptive pain from tissue injury, neuropathic pain from nerve damage, and nociplastic pain in which the nervous system itself has become sensitized.

Because pain cannot be measured directly, it is assessed through self-report tools such as numeric rating scales, visual analog scales and questionnaires that ask about intensity, location, quality and interference with daily activities. In animals, veterinarians rely on behavioral signs such as reluctance to move, changes in posture, appetite or grooming, and validated observer scales. Cannabinoids have been studied for several types of pain, and the endocannabinoid system is known to take part in pain signaling, but clinical evidence in people remains limited and mixed, and no cannabidiol product has an approved use for pain.