Small medical thermometer

Quantity limits: One small clinical/medical mercury thermometer.

The thermometer must be in a protective case.

Regulation that allows it: 49 CFR 175.10(a)(7)

Tip: Thermometers with a red line instead of silver are not mercury and not restricted. Digital thermometers are also not restricted.

Though allowed in checked and carry-on baggage by U.S. regulations, medical mercury thermometers are not allowed in carry-on baggage by international (ICAO/IATA) regulations.