A small study revealed that the drugs may retain their original efficacy even if they expire years ago and have not been kept at a proper temperature all along.
This is good news for workers in remote areas of the world where the drug is sometimes out of reach. The alternative is the absence of any treatment for a serious illness, the researchers wrote in the journal Wilderness & Environmental Medicine.
Dr Emma Brown, who led the research team, said: "The validity date of any drug packaging indicates the last date that the pharmaceutical company guarantees the safety of the property when stored in the recommended conditions and in the original packaging package."
"This date is not necessarily the date when the drug becomes ineffective or dangerous and in many drugs it may be much longer than the usual validity period of two to three years," she said.
"In some parts of the world, doctors have difficulty getting access to drugs more than once a year," she said. It may also be costly for small communities or exploration teams to replace unused drugs.
The team tested the effectiveness of five expired drugs retrieved from the British Antarctic Survey, which operates five bases and two ships in the Antarctic region and owns medical facilities at these sites.
Antarctica's drugs are ordered once a year in May and shipped from Britain in September and reach bases in December after spending several months at sea, the researchers said.
They added that the drugs tested had cut this trip again when they were returned because of the expiration date.
The researchers tested five types of drugs that took between one and four years to expire and compared these drugs with modern samples of the same drugs to determine the effectiveness and efficiency of the active ingredient.
All the tested drugs were found to be theoretically effective. But researchers cautioned that they did not know exactly how hot the drugs were.
"There are huge amounts of medicines that are disposed of because of their expiry, and this is a cost to patients through taxes, insurance and other medical bills," Brown said.