When Does Novolin N Expire After Being Used For The First Time?

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.

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 store 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

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

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!