Few things feel better than a hot soak on a cold day. But the right temperature for bathing has been hotly debated since before the time of ancient Rome. One expert, Dr. Melissa Piliang, a dermatologist with the Cleveland Clinic, dives into why young people can handle heat better than old folks and explains why 112 is the magic number.

The Goldilocks bath
Hot water from the tap can run as high as 140 degrees Fahrenheit, but most doctors recommend setting home water heaters to 120 degrees to prevent injury, Dr. Piliang says. The optimal temperature to wash away environmental dirt and bacteria, she says, is 112 degrees or lower, “though you’d have to put a thermometer under the spigot to get an exact reading.” A shower or bath “should feel warm and not uncomfortably hot,” she says.

The epidermis has an outside fatty lipid layer for protection. “It is what keeps bad water and germs out and good water in, and keeps our skin moisturized,” Dr. Piliang says. She compares the fatty layer to butter on a knife: It stays put if held under cold water but melts away under a hot stream. That is similar to what a hot shower over 112 degrees does to the protective layer of people’s skin, she says.

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