Does cefazolin expire?
The printed date covers the sealed pack. Once cefazolin is opened, mixed or diluted, its label sets a second and usually much shorter limit — quoted below, per product.
Shortest limit on any cefazolin label: 4 hours
“DISCARD ANY UNUSED PORTION AFTER 4 HOURS .”
That applies to the product it is printed on, not to every form of cefazolin — check which one you have against the list below.
What the labels say
“DISCARD ANY UNUSED PORTION AFTER 4 HOURS .”
On the label for Cefazolin · DailyMed
“Discard vial within 4 hours after initial entry.”
On the label for Cefazolin · DailyMed
“If prompt fluid transfer cannot be accomplished, discard the contents no later than 4 HOURS after initial closure puncture.”
On the label for Cefazolin · DailyMed
“L 319 mg/mL 100 mL 30 mg/mL Storage of Reconstituted and Diluted Solutions When reconstituted or diluted according to the instructions above, Cefazolin for Injection is stable for 4 hours at room temperature or for 3 days if stored under refrigeration at 2°C to 8°C (36°F to 46°F).”
On the label for Cefazolin · DailyMed
“Discard any unused portion after 4 HOURS .”
On the label for CEFAZOLIN · DailyMed
“The entire contents of the bag must be used within 4 hours from the time of initial entry.”
On the label for CEFAZOLIN · DailyMed
“When reconstituted or diluted according to the instructions below, Cefazolin for Injection is stable for 24 hours at room temperature or for 10 days if stored under refrigeration (5°C or 41°F).”
On the label for Cefazolin · DailyMed
“When reconstituted or diluted according to the instructions below, Cefazolin for Injection, USP is stable for 24 hours at room temperature or for 10 days if stored under refrigeration (5°C or 41 °F).”
On the label for Cefazolin · DailyMed
“Sterile Water for Injection Ringer’s Injection, USP 5% Sodium Bicarbonate Injection, USP When diluted according to the instructions above, cefazolin is stable for 24 hours at room temperature or for 10 days if stored under refrigeration (5ºC or 41ºF).”
On the label for Cefazolin · DailyMed
“Note: Following reconstitution (activation), product must be used within 24 hours if stored at room temperature or within 7 days if stored under refrigeration.”
On the label for Cefazolin Sodium · DailyMed
“L 196 mg/mL 100 mL 30 mg/mL Storage of Reconstituted and Diluted Solutions When reconstituted or diluted according to the instructions above, Cefazolin for Injection is stable for 24 hours at room temperature or for 7 days if stored under refrigeration at 2°C to 8°C (36°F to 46°F).”
On the label for Cefazolin · DailyMed
“The product must then be used within 7 days, but not beyond the labeled expiration date.”
On the label for Cefazolin Sodium · DailyMed
How the label says to keep cefazolin
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.
- “Before reconstitution protect from light and store at 20° to 25°C (68° to 77°F) [See USP Controlled Room Temperature].”
- “Before reconstitution protect from light and store at 20° to 25° C (68° to 77°F) [See USP Controlled Room Temperature].”
- “As with other cephalosporins, Cefazolin for Injection, USP tends to darken depending on storage conditions; within the stated recommendations; however, product potency is not adversely affected.”
- “Before reconstitution, protect from light and store at 20º to 25ºC (68º to 77ºF) [see USP Controlled Room Temperature].”
- “Store the unactivated unit at 20-25°C (68-77°F).”
- “As with other cephalosporins, reconstituted Cefazolin for Injection USP and Dextrose Injection USP tends to darken depending on storage conditions, within the stated recommendations.”
- “To avoid inadvertent activation, the DUPLEX ® Container should remain in the folded position until activation is intended.”
- “Protect from light after removal of foil strip.”
Frequently asked questions
Does cefazolin 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 4 hours on some cefazolin products, and that is the number quoted on this page.
Can I still use cefazolin 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 cefazolin 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 cefazolin
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.