Short answer: Keep unopened Humulin N in the fridge at 36-46°F (2-8°C) until the expiration date. At room temperature up to 86°F (30°C), a vial lasts 31 days and a KwikPen 14 days, counting unopened and in-use time together. Opened vials may be refrigerated; an in-use KwikPen is not. Do not use Humulin N that froze. Source: Humulin N label, section 16.2.
What does the Humulin N label say?
Section 16.2: “Protect from heat and light. Do not freeze. Do not use if it has been frozen.”
Humulin N US prescribing information, section 16.2, Table 2.
| Form | Unopened, room temp (up to 86°F) | Unopened, refrigerated | In use, room temp (up to 86°F) | In use, refrigerated |
|---|
| 10 mL multiple-dose vial | 31 days | Until expiration date | 31 days | 31 days |
| 3 mL KwikPen | 14 days | Until expiration date | 14 days | Do not refrigerate |
Table footnotes: “When stored at room temperature, HUMULIN N vial can only be used for a total of 31 days including both not in-use (unopened) and in-use (opened) storage time.” For the KwikPen the same footnote gives “a total of 14 days”.
Why are the numbers different from other insulins?
Many insulin labels give 28 days at room temperature. Humulin N gives 31 days for a vial and 14 days for a KwikPen, and both count all room-temperature time together, unopened and in use. A pen that sat out unopened for 5 days has 9 days left once you start it. Keeping spares in the fridge keeps the full time for when they are opened.
What do the Instructions for Use add?
- Unopened vials: “Store all unopened vials in the refrigerator. Do not freeze. Do not use if it has been frozen. Keep away from heat and out of direct light.” Stored at room temperature, they are thrown away after 31 days.
- Opened vials: in the fridge or at room temperature up to 86°F (30°C) for up to 31 days, then thrown away even if insulin is left.
- KwikPen in use: “Store the Pen you are currently using at room temperature [up to 86°F (30°C)]. Keep away from heat and light. Throw away the HUMULIN N Pen you are using after 14 days, even if it still has insulin left in it.” Do not store the pen with the needle attached.
- Humulin N is a cloudy suspension. The Instructions for Use describe rolling and turning the vial at least 10 times each, or the pen 10 times each, before a dose so it looks white and cloudy, and not using it if it looks clear or has lumps or particles.
See the Humulin N dosing schedule, Humulin N side effects, the insulin pen glossary entry, and the Humulin R U-500 page for Lilly’s concentrated human insulin.
How do you travel with it?
An in-use Humulin N vial or KwikPen travels at room temperature, up to 86°F (30°C), for the rest of its 31 or 14 days. Unopened spares start using up that time as soon as they leave the fridge. Keep them off direct contact with an ice pack, since frozen Humulin N is not used.
- TSA allows medically necessary liquids over 3.4 oz in carry-on bags; declare them at the checkpoint for inspection.
- Unused syringes and pen needles are allowed when they travel with the injectable medicine.
- Ice packs and gel packs that keep medicine cool may go through frozen, partly frozen or melted.
- Keep medicine in your carry-on, not checked luggage, where you cannot control the temperature. Do not let it touch an ice pack directly, since most labels say do not freeze.
More in the travel guide.
Quoted from the current US label on DailyMed, not personalized advice. Labels change; the leaflet in your own carton, your pharmacist and your prescriber are the final word on how to store it.