When Does Novolin N Expire After Being Used For The First Time?
In our latest question and answer, the pharmacist discusses how soon after opening Novolin N products expire.
I have been in hospitals and skilled nursing for almost 3 months, due to two surgeries. Before I left in June, I had drawn from my Novolin N bottle one time. It has been in the refrigerator this whole time. Is it safe to use?
Aug 26, 2021- Once opened, a Novolin N vial stays good for 42 days when stored at room temperature below 77°F and should not be refrigerated after opening. After 42 days, the opened vial should be discarded because expired insulin may be less effective and could cause unpredictable changes in blood sugar levels. If your vial has been open for more than 42 days, you should replace it with a new one.
Hello and thank you for your question!
The expiration date of Novolin N will vary based on several conditions, including:
- Which Novolin N product it is (vial or pen)
- If it has been opened (i.e. used) yet
- If it has been stored at room temperature or in the fridge
Since you asked about Novolin N vials, I'll touch on that first.
Novolin N Vial Expiration
All of the following information regarding Novolin N expiration is supplied directly from the manufacturer.
| Not In-use (Unopened) Refrigerated (36°F - 46°F [2°C - 8°C]) | Not In-use (Unopened) Room Temperature | In-use (Opened) Room Temperature | |
| Novolin N Vials 10 mL Expiration | Until expiration date listed on box/vial | 42 days below 77°F (25°C) | 42 days below 77°F (25°C) Do not refrigerate |
I want to point out here that there is no section in the above table for an in-use vial of Novolin N, stored in the refrigerator. This is because the manufacturer states that opened vials should be stored at room temperature, not in the refrigerator.
Per the prescribing information of Novolin N:
After vials have been opened:
o Opened Novolin N vials can be stored at room temperature below 77° F (25° C). Do not refrigerate.
The prescribing information doesn't state why an open vial shouldn't be stored in the refrigerator, but reasons likely include:
- Injecting cold insulin is generally more painful than injecting room temperature insulin.
- Stability issues with the insulin could arise if it consistently experiences temperature changes from removing, and replacing the vial in the refrigerator with each dose, although there isn't published data to confirm or refute this.
So, in the situation you mentioned in your question, you opened a vial of Novolin N insulin, used it for one dose, and put it in the refrigerator.
Even though it isn't recommended to put it back in the refrigerator after opening, it would be prudent to still follow the listed expiration dates in the table above... that an open vial of Novolin N is considered expired after 42 days, and should be discarded.
Since your vial has been open for more than 42 days, you should not use it.
Novolin N FlexPen Expiration
| Not In-use (Unopened) Refrigerated (36°F - 46°F [2°C - 8°C]) | Not In-use (Unopened) Room Temperature | In-use (Opened) Room Temperature | |
| Novolin N FlexPen 3 mL Expiration | Until expiration date listed on box/pen | 28 days below 86°F (30°C) | 28 days
below 86°F (30°C)
Do not refrigerate. |
The same situation regarding refrigeration for the vials applies to the pens. The manufacturer states that an opened (i.e. used) pen should be stored at room temperature, not in the refrigerator
Final Words
Since your Novolin N vial is expired, I strongly recommend you replace it with an in-date, non-expired product.Expired insulin may be degraded, and not as potent as it once was. Injecting it may cause fluctuations in blood sugar that are unexpected, leading to inadequate blood sugar control.
Thank you again for your question and be sure to reach out to us any time!
References & sources
Glossary — Terms in This Answer
- Novolin N
- A type of insulin medication used to help control blood sugar levels in people with diabetes.
- Vial
- A small sealed bottle used to store and dispense liquid medication like insulin.
- In-use
- A medication that has been opened and started to be used, as opposed to still being sealed and unused.
- Prescribing information
- Official instructions from the medication manufacturer that describe how to properly use and store a drug.
- Stability
- The ability of a medication to maintain its strength and effectiveness over time under certain conditions.
- Potent
- Having strong effectiveness or power to produce a desired effect.
- Degraded
- Reduced in quality, strength, or effectiveness over time.
- Blood sugar control
- The ability to maintain healthy levels of glucose in the bloodstream.
Dr. Brian Staiger, PharmD
Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified
Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...
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