What causes your fingers to swell?

Answer 1

Q: Why do your fingers/hands and toes/feet itch and swell in the cold?

A: The second law of thermodynamics states that heat flows naturally from an object at a higher temperature to an object at a lower temperature, and heat doesn't flow in the opposite direction of its own accord. With respect to your fingers/hands and toes/feet, when they are out in reasonably to extremely cold temperatures, the heat from them flows rapidly to the air. How fast they lose heat depends on the temperature of the cold fluid. Fluid being liquid or gaseous (air). The difference in the fluid temperature and your body temperature determines the driving force or how fast the heat leaves through your extremities. When this process occurs, the body automatically begins to pump blood at a faster rate per the heat being loss (change in blood pressure). This process increases the blood pressure rapidly to the extremities and causes them to swell and hurt.

Answer 2

The blood vessels in your fingers are dilating so that they can get closer to the surface and release some of your excess body heat by evaporative cooling. Your body is trying to cool itself off by cooling that which circulates inside of it- blood.

Answer 3

Water retention