What is the difference between hyperalgesia and allodynia?

Prepare for the Tissue Injury, Healing, and Pain Test. Utilize flashcards and multiple-choice questions with hints and explanations. Ensure you're ready for the exam!

The key idea is that these terms describe different ways in which the pain system becomes more responsive after injury. Hyperalgesia means an amplified pain response to a stimulus that is normally painful (a noxious stimulus). In other words, the same poke or pinch hurts more than usual because the pain pathways are sensitized. Allodynia means pain elicited by a stimulus that would not normally cause pain, such as light touch or a gentle breeze; this happens when non-painful inputs start activating pain pathways, often due to central sensitization.

So the correct distinction is that hyperalgesia is increased pain from a painful stimulus, while allodynia is pain from a normally non-painful stimulus. The other ideas—pain from non-painful stimuli being hyperalgesia, or the two being the same, or decreased pain to painful stimuli—don’t capture these specific relationships between stimulus type and pain.