The shelf life of antiviral drug Tamiflu can be extended from five to seven years, European experts have recommended.
After it is approved by the European Commission, this will apply to all newly manufactured Tamiflu capsules.
London-based European Medicines Agency (EMEA) has also said that the five-year expiry date on medicines already in the market can be extended by two years in the event of a pandemic.
However, the agency said: "These recommendations will only apply if a pandemic has been declared by the World Health Organization."
The recommendations follow a study on measures to prevent shortage of antiviral drugs during flu pandemics, a statement from the EMEA said.
It also advised on the use of Tamiflu for young children and expectant mothers in case of an officially declared A/H1N1 pandemic.
"The benefits of the use of Tamiflu outweigh its risks in the treatment of children under the age of one," the experts said, adding that they had reached the same conclusion for pregnant and breastfeeding women.
However, they said that in the case of young children "doctors should carefully consider the benefits and risks for each patient".