Insulin Clinics / Starting and managing
How long can insulin be out of the fridge?
Most insulin can be kept at room temperature for weeks once it is out of the fridge — but the exact limit depends on the product, and heat or freezing can ruin it in hours.
Last updated: October 2026 · Based on ADA Standards of Care, FDA prescribing information, and NIDDK · General information, not medical advice — see our editorial policy
The short answer
Insulin is usually fine at ordinary room temperature — up to 86°F (30°C) — for a set number of days that depends on the product, often 28 days. Once insulin has been taken out of the fridge, that room-temperature "clock" has started, whether or not the pen or vial has been opened. What damages insulin is heat above about 86°F, direct sunlight, and freezing.
Room-temperature limits by insulin
These figures are typical values from U.S. prescribing information as of 2026. Manufacturers sometimes update them, and vials and pens of the same insulin can differ — the package insert for your product is the final word.
| Insulin | Typical limit at room temperature (up to 86°F / 30°C) |
|---|---|
| Rapid-acting: lispro, aspart, glulisine (Humalog, Admelog, Novolog, Apidra and unbranded versions) | ~28 days |
| Ultra-rapid: faster aspart (Fiasp), lispro-aabc (Lyumjev) | ~28 days |
| Glargine U-100 (Lantus, Basaglar, Semglee, Rezvoglar) | ~28 days |
| Glargine U-300 (Toujeo) | ~56 days |
| Degludec (Tresiba) | ~56 days |
| Detemir (Levemir, where available) | ~42 days |
| Human regular and NPH insulin — vials | ~31–42 days depending on manufacturer |
| Human NPH and 70/30 premixed — pens | As short as ~10–14 days for some pens; others longer |
| Analog premixes (for example lispro or aspart mixes) — pens | ~10–14 days |
| Analog premixes — vials | ~28 days |
Write the date you took the insulin out of the fridge on the label. Discard it when the period ends, even if insulin is left.
Can insulin go back in the fridge?
Putting insulin back in the fridge does not reset the clock. Whether an in-use pen should be refrigerated at all differs by product: some labels say in-use pens should be kept at room temperature and not refrigerated, while in-use vials can often be kept either way. Check the leaflet for your product.
Insulin left out by mistake
- Left at normal room temperature overnight or for a few days: generally still usable — count the days from when it came out, within the product's room-temperature limit.
- Left somewhere hot (a car, direct sun, a mailbox or doorstep in summer): it may have lost strength without looking any different. If you can, replace it. If you have to use it, watch your readings closely, and switch to a new pen or vial if readings are unexpectedly high.
- Frozen (even once, even if it has thawed): do not use it.
- Looks wrong — clear insulin that is cloudy, discolored, or has particles; cloudy insulin with clumps or frosting: do not use it.
If you are unsure, ask your pharmacist. Unexplained high readings after using insulin that may have been damaged are a reason to open a new supply and contact your care team.
Mailing or shipping insulin
Sometimes insulin needs to be sent somewhere — to a family member who forgot their supply, or back to a pharmacy. A few principles:
- Room-temperature insulin does not have to be shipped cold to stay usable, because its in-use clock has already started. The real risk in transit is heat and freezing in vans, mailboxes, and on doorsteps.
- Use the fastest service available, avoid shipping right before weekends or holidays, and arrange for someone to receive it promptly.
- Insulate the package. An insulated mailer helps buffer temperature swings. If using cold packs, wrap them so they never touch the insulin directly — contact freezing ruins it.
- Check the carrier's and destination's rules. Carriers and countries have rules about mailing or importing prescription medicines.
- Inspect on arrival. If the package arrives hot, or the insulin is frozen or looks abnormal, do not use it.
Mail-order insulin deliveries
Pharmacies that ship insulin usually pack it with cold packs. When it arrives, put unopened supply in the fridge straight away. If a delivery arrives warm, frozen, or damaged, contact the pharmacy before using it — many will replace it.
Frequently asked questions
How long can insulin be out of the fridge?
It depends on the product — commonly 28 days at room temperature up to 86°F (30°C) for rapid-acting insulins and glargine U-100, up to 56 days for degludec and glargine U-300, and as little as 10–14 days for some premixed and NPH pens. Check your package insert.
Is insulin still good if it was left out overnight?
If it stayed at normal room temperature (below 86°F / 30°C), it is generally fine. Its room-temperature clock started when it came out of the fridge.
Do I need to cold-ship an insulin pen that has been at room temperature?
It does not need to be kept refrigerated during shipping, but it does need protecting from heat and freezing. Use fast shipping, insulated packaging, and cold packs that do not touch the insulin; check the carrier's rules for mailing medicines.
What happens if insulin gets too hot?
Heat breaks down insulin so it works less well, usually without any visible change. Replace insulin that has been exposed to high heat if possible, and watch for unexplained high readings.
Can I use insulin after it has been frozen?
No. Frozen insulin should be thrown away, even if it looks normal after thawing.