The dose-related effects of paracetamol on hyperalgesia and nociception in the rat.

1. We have studied the effects of 3 low doses of paracetamol (25, 50 and 100 mg kg-1 p.o.) on inflammatory hyperalgesia, inflammatory oedema, and nociceptive thresholds in rats. 2. At the lower dose (25 mg kg-1), paracetamol reduces only central hyperalgesia. 3. At the doses of 50 and 100 mg kg-1, paracetamol reduces also peripheral hyperalgesia; moreover, it enhances nociceptive thresholds to a mechanical stimulus in the non-inflamed paws. 4. Neither paw inflammatory oedema nor tail nociceptive thresholds to a thermal stimulus were modified by paracetamol administration. 5. Our results suggest that paracetamol can reduce hyperalgesia without affecting physiological nociception and inflammation.