Out of curiosity to see if it would make any difference, I recently requested a prescription for Humalog from the FNP-C who treats me at the local (Syracuse) VA. The relatively new (to me) prescription includes the additional caveat below.


This warning was not on my previous Novolog (insulin apart) prescriptions. Huh? :confused:

Maybe this is just some new bureacratic boilerplate that is now added to any insulin prescription. But I decided I would ask if anyone knows of a reason insulin lispro might be considered relatively less stable than insulin aspart.

Frankly it makes no sense to me that anything about popping the plastic protective cap off a vial of insulin would make a drastic difference in how quickly the insulin could degrade. I would think other factors such as the temperature the insulin is stored at or exposure to light would be more important than removing the vial’s cover.

It usually takes me around 25 days or less to empty a vial of insulin. So this warning won’t change anything about the way I use insulin. The warning just strikes me as, well, excessive? :thinking: :man_shrugging:

The 28 day rule has been around a long time.
Below for humalog. I think printing on RX label may be new (but normal for that pharmacy), but the paper instructions inside box have always said it.
Doesn’t mean we all follow it.
For pens that are carried around in warmer temps, there may be higher chance of degraded insulin.
I use my vial to fill pump, then return to refrigerator, and don’t discard until gone, usually 30-35 days.

From humalog website:
How should I store HUMALOG?

All unopened vials:

  • Store all unopened vials in the refrigerator at 36°F to 46°F (2°C to 8°C).
  • Do not freeze. Do not use if HUMALOG has been frozen.
  • Keep away from heat and out of direct light.
  • Unopened vials can be used until the expiration date on the carton and label, if they have been stored in the refrigerator.
  • Unopened vials should be thrown away after 28 days, if they are stored at room temperature.

After vials have been opened:

  • Store opened vials in the refrigerator or at room temperature below 86°F (30°C) for up to 28 days.
  • Keep vials away from heat and out of direct light.
  • Throw away all opened vials after 28 days of use, even if there is insulin left in the vial.

From Novolog:

Storage conditions for NovoLog® FlexPen®, 3‑mL PenFill® cartridge, and 10‑mL vialb-d

closed medicine container icon

Storage before use

  • Store unused NovoLog® pens, PenFill® cartridges, and vials at room temperature up to 86°F for up to 28 days
  • Store unused NovoLog® pens and vials in refrigerator at 36°F to 46°F until expiration

open medicine container icon

Storage after use

  • Keep at room temperature (below 86oF) or refrigerated for up to 28 days
  • Keep away from direct heat and light
  • Dispose after 28 days, even if there is insulin left in the pen or vial
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It takes me longer than a month to use up my pens. I use Novolog and Tresiba. My insulin sometimes goes bad before I can use it, so I have started throwing it out after about 28 days. I keep my opened pens in a drawer or in my purse.

I only keep my humalog in the fridge. I often go past 28 days. It’s never gone bad. Except on super hot days, I’ve had it go bad inside my pump only.
I just notice I need more and more, then either my site is bad or insulin is.
If it’s over 90 out, I assume it is insulin. When it’s over 100, I know it’s the insulin