If pain is allowed to go on uninhibited it may become more intense and difficult to relieve. A continuous afferent input of signals from the injured tissue will gradually sensitize dorsal horn neurones of the spinal cord, making them more receptive for transmission of pain messages to the brain cortex. The pain signal should be stopped at the periphery. Preventive use of peripheral and spinal nerve blocks, including local anaesthetics, and administration of non-steroidal antiinflammatory drugs and opioids can reduce the effects leading to sensitization. The best treatment is--pre-emptive analgesia--administered before the pain is established. Pain that is not adequately treated may lead to persistent morphological changes in the central nervous system, resulting in chronic pain refractory to treatment.