Does zidovudine expire?
The printed date covers the sealed pack. Once zidovudine is opened, mixed or diluted, its label sets a second and usually much shorter limit — quoted below, per product.
Shortest limit on any zidovudine label: 24 hours
“After dilution, the solution is physically and chemically stable for 24 hours at room temperature and 48 hours if refrigerated at 2°C to 8°C (36°F to 46°F).”
That applies to the product it is printed on, not to every form of zidovudine — check which one you have against the list below.
What the labels say
“After dilution, the solution is physically and chemically stable for 24 hours at room temperature and 48 hours if refrigerated at 2°C to 8°C (36°F to 46°F).”
On the label for RETROVIR · DailyMed
How the label says to keep zidovudine
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.
- “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 to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature].”
- “Store at 15° to 25°C (59° to 77°F) and protect from moisture.”
- “Store at 15° to 25°C (59° to 77°F).”
- “Store vials at 15° to 25°C (59° to 77°F) and protect from light.”
Frequently asked questions
Does zidovudine 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 zidovudine products, and that is the number quoted on this page.
Can I still use zidovudine 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 zidovudine 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 zidovudine
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.