Does foscarnet expire?
The printed date covers the sealed pack. Once foscarnet is opened, mixed or diluted, its label sets a second and usually much shorter limit — quoted below, per product.
Shortest limit on any foscarnet label: 24 hours
“Solutions thus prepared should be used within 24 hours of first entry into a infusion bag.”
That applies to the product it is printed on, not to every form of foscarnet — check which one you have against the list below.
What the labels say
“Solutions thus prepared should be used within 24 hours of first entry into a infusion bag.”
On the label for Foscarnet Sodium · DailyMed
“Solutions thus prepared should be used within 24 hours of first entry into infusion bag.”
On the label for FOSCARNET SODIUM · DailyMed
“Solutions thus prepared should be used within 24 hours of first entry into a sealed bottle or infusion bag.”
On the label for Foscarnet Sodium · DailyMed
“Solutions thus prepared should be used within 24 hours of first entry into a sealed bottle.”
On the label for foscarnet sodium · DailyMed
How the label says to keep foscarnet
Storage is the other half of the question: the stability behind any date assumes these conditions, and a medicine kept outside them ages faster than the calendar says.
- “Conditions Store at 20° to 25°C (68° to 77°F).”
- “Protect from excessive heat (above 40°C) and from freezing.”
- “Store between 20° and 25°C (68° and 77°F) [See USP Controlled Room Temperature].”
- “Store between 20° and 25°C (68° and 77°F) [see USP Controlled Room Temperature].”
- “Conditions Store at 20° to 25°C (68° to 77°F) [See USP Controlled Room Temperature].”
- “Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature].”
- “Store at 20˚ to 25˚C (68˚ to 77˚F), excursions permitted between 15˚ to 30˚C (59˚ to 86˚F) [see USP Controlled Room Temperature].”
- “Store at 20° to 25°C (68° to 77°F) [See USP Controlled Room Temperature].”
Frequently asked questions
Does foscarnet expire?
Two different clocks apply and only one of them is the printed date. The date on a sealed pack is the manufacturer's guarantee for the unopened product. Once it is opened, mixed or diluted, the label imposes its own limit — as tight as 24 hours on some foscarnet products, and that is the number quoted on this page.
Can I still use foscarnet after the date on the box?
This page cannot tell you that, and nor can any page. The FDA's own shelf-life programme found 88% of tested lots stayed within specification at least a year past expiry — and concluded in the same breath that lot-to-lot variation means this can only be confirmed by testing each lot. What you can check at home is the in-use limit above and whether the product has been stored as the label requires. Ask a pharmacist about a specific pack; they will also dispose of what you no longer need.
Why do different foscarnet products have different limits?
Because they are different formulations. A suspension that gets mixed with water, a pen that gets carried at room temperature, and a sealed tablet do not behave alike, so each manufacturer's label sets its own limit and each is shown here with the product it belongs to. We never merge them into one number for the molecule.
More on foscarnet
Quoted from FDA labels for reference, not medical advice, and not a suggestion to use anything past its limit. If you are unsure whether a pack is still good, a pharmacist can tell you and can dispose of it safely.