Why does your skin go red after a hot shower?

The body has a core temperature of about 98.6F for most people. If you are in a hot environment, or have just taken a nice hot shower/bath, your core body temp is going to be affected. To get rid of the heat, the superficial blood vessels, just under your skin, dilate to release the heat to the skin, sometimes in the form of perspiration with a little help from the eccrine (sweat) glands. When those blood vessels dilate so close to the surface of the skin, it causes the skin to become red, flushed or florrid.