The tiny ingestive capsule is changing the way Australian firefighters work on the front line.
The pill can relay an individual's core temperature in real time, giving a better understanding of the body's vulnerability to heat stress to protect firefighters.
Victoria's Country Fire Authority health and wellbeing officer Peter Langridge said the data gathered in a CFA trial had led to changes in firefighters' work patterns, including the length of time they are exposed to blazes.
About 50 CFA firefighters swallowed the data-gathering pill during a training exercise in which they evacuated 20 people from a burning medical centre.
The Equivital EQ02 LifeMonitor capsule used in the CFA trial is a plastic-coated pill containing a thermometer and small transmitter.
Core temperature measurements from the thermometer are fed through the transmitter to a device worn on the chest, which collects skin temperature, heart and respiration rate data, which is then sent to an external computer.
The CFA research has tested firefighters' core temperature when they are exposed to temperatures ranging from -3C to 124C, for about 20 minutes, Mr Langridge said.
Changes in the body's core temperature over time were analysed, giving researchers information about the danger periods.
"As the (external) temperature rises we see the core temperature going up earlier," Mr Langridge said.
The CFA looked for ways to assess core body temperature more accurately after the standard test - measuring temperature via the ear - was found to be ineffective.
"We were seeing firefighters that still looked heat-stressed, even though the temperature on the ear probe was showing normal," Mr Langridge said.
Firefighters working in extreme conditions during the 2009 Black Saturday bushfires in Victoria also succumbed to heat stress, despite following hydration procedures, he said.
This prompted action to find ways to better manage the condition, Mr Langridge said.
A heat-stressed firefighter can be treated in a number of ways, including applying wet towels to their arms, submerging the arms in water or placing ice packs placed under their armpits, or a combination of these, he said.
Research using the capsule will continue, with trials planned to test the device at temperatures ranging from 100C to 600C, Mr Langridge said.
The device was recently used to measure skydiver Felix Baumgartner's vital signs during his world-record jump to earth from space.
And for anyone who is wondering, the pill is usually expelled naturally from the body within one to two days of ingestion.
By Michelle Henderson, AAP National Medical Writer