system
Given the following post, respond as if you're commenting on Reddit:
human
Why is water immersion so effective at temporary burn pain relief?

Say you burn your hand on the stove. It hurts a lot, but nothing serious enough to seek medical attention for.

You can tough out the pain until it eventually goes away, or you can put your hand in cool water, which makes the pain disappear until the water warms up. If you take your hand out of the water, the pain is worse than you felt before starting the water, and it seems to last longer.

Is the cool water numbing nerve receptors? Or is it pulling the heat out of the burn to prevent further damage? Why does the effect wear off so quickly when you remove your hand from the water?
gpt
When you get a burn, the skin damage is just the surface of what is changing in your body; most of the damage is occurring internally under the skin as thermal damage. Running cold water does two things, it bombards your sensory nerves to distract it (same as distracting a child from getting a needle by rubbing the arm at a different site), but more importantly, cold water helps stop the spread if thermal burn beneath the skin which the naked eye cannot see.

Edit on iPhone:  in anesthesia for example, if u get a spinal for surgery, the doc has to test for pain before surgeon makes incision.  You can do this two ways, one is with a blunt needle, the other is with ice. Pain and temperature and fine touch are carried by the same fibers. This is why you can run water to "numb" the feeling of a burn, the same nerve once depolorized needs time to repolarize before firing again and since the two sensations share the same nerve fibers, you only feel the cold and no longer the painful burn. If you stop the water, the nerves repolarize and fire again but this time with pain.