Your brain and spinal cord actually produce their own pain killers. These are similar to pain relieving drugs like morphine.
Two of these are called endorphins and enkephalins, which, when they are released, they attach themselves to spinal receptors in your brain, which produce ‘stop-pain’ messages.
On the other hand, some substances in your body do completely the opposite. They intensify your pain.
A protein called substance P then stimulates nerve endings at the site of the injury, increasing pain messages.
Other pain enhancers work by activating normally silent nerve cells in the injured area. This then sends pain messages which can actually worsen the pain you are in and make the area of pain