How Long Does an Opened Humalog Vial Last?
A vial of Humalog (insulin lispro) remains usable for 28 days after first use when stored at room temperature (up to 86°F or 30°C) or refrigerated (36–46°F or 2–8°C). Do not freeze it, and avoid direct heat or sunlight. Discard after 28 days even if insulin remains.[1]
What If I Refrigerate vs. Keep at Room Temperature?
Refrigeration extends stability but isn't required post-opening—both options allow the full 28 days. Room temperature suits daily convenience without risking potency loss within limits. Always mark the opening date on the vial.[1]
Does This Apply to Humalog KwikPen or Other Forms?
No—pens last 28 days unrefrigerated after first use, matching vials. Humalog Mix 75/25 vials or pens drop to 10 days at room temp or 28 days refrigerated. Check the label for your exact product.[1]
Signs an Opened Vial Has Gone Bad
Inspect before each injection: clear, colorless insulin is good. Discard if cloudy, thickened, discolored, or containing lumps/particles. Unopened vials last until the expiration date if refrigerated.[1]
Why the 28-Day Limit and Storage Rules?
Insulin degrades from exposure to air and temperature after puncture. Manufacturers test stability to ensure safe blood sugar control—using beyond 28 days risks reduced effectiveness or infection.[1]
[1] Humalog Prescribing Information, Eli Lilly and Company, https://pi.lilly.com/us/humalog-uspi.pdf
[2] DrugPatentWatch.com (related insulin patent data), https://www.drugpatentwatch.com/p/tradename/HUMALOG