If you take insulin, you might be shocked at the sticker price. Newer insulins can run in the hundreds of dollars for a box of pens. Insurance and Medicare will likely cover some, if not all, of the cost (if it’s part of your health plan’s formulary), but the price is high for many, and there are sad stories of people who simply cannot afford it. It’s no wonder that every drop of insulin is precious, and wasting it seems unheard of.
Does insulin expire? Insulin expiration dates
Common questions that frequently pop up for people with diabetes are: Does insulin expire? And can you use your insulin if it’s expired? Yes, insulin does expire. And what you need to know is that insulin has TWO expiration dates:
- Expiration date on the insulin vial box or pen — usually one year after the purchase date
- Expiration date once you’ve opened the insulin vial or pen
The expiration date once you’ve opened the insulin vial or insulin pen is different than the date printed on the box. “Open” means that you’ve removed the cap and punctured the rubber stopper on the vial with your syringe needle, or you’ve used the insulin pen for the first time.
- Opened insulin vials generally last for only 28 days
- Opened pens will generally last for between 28 and 56 days after the first use, depending on the type of insulin
Here are some examples of the differences in insulin expiration dates after opening:
- Novolog FlexPen: 28 days after first use
- Novolog vial: 28 days after opening
- Humalog KwikPen: 28 days after first use
- NPH Humulin vial: 42 days after first use
- NPH Novolin FlexPen: 28 days after first use
- Levemir vial: 42 days after first use
- Levemir FlexPen: 42 days after first use
- Tresiba FlexTouch Pen: 56 days after first use
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What happens when insulin “expires”
Insulin helps keep your blood sugar levels within your target range which, in turn, keeps you safe from both short-term complications (e.g., high and low blood sugars, diabetic ketoacidosis) and long-term complications (e.g., heart disease, eye problems, nerve damage). If your insulin isn’t working as it should, you run the risk of developing serious problems.
Insulin manufacturers are required to do rigorous studies and testing before their products meet potency guidelines required by the Food and Drug Administration (FDA). When it comes to the expiration date printed on the box, the manufacturer has to pretty much guarantee that the insulin will work as expected within the expiration date (as long as the insulin is stored properly).
The expiration date does not mean that, all of a sudden, your insulin will stop working. But it does mean that it may not work the same way it did when you first opened it. Once you open a vial of insulin or an insulin pen, the efficacy of that insulin begins to decrease over time. If you continue to insulin once it has expired, there is no guarantee that it will help you keep your blood sugars within your target range. You may start to notice, for example, that your blood sugars are running higher than usual, even though you’re taking the same amount of insulin, eating the same amount of carbs, etc. You might even notice symptoms of high blood sugar, which include:
- Feeling tired
- Having to urinate often
- Blurry vision
Storing your insulin
Along with being aware of insulin expiration dates, it’s important to store — and inspect — your insulin properly. What does this mean?
- Store unopened insulin in the refrigerator at a temperature between 36°F and 46° F.
- Keep opened insulin (that you’re using) at room temperature, between 56°F and 80°F.
- Never leave insulin in a hot car or in sunlight. Heat and light break down insulin.
- Never freeze insulin. Don’t use insulin if it’s been frozen and thawed.
- Don’t keep your insulin on the refrigerator door. The constant movement of the door can jostle the insulin around and possibly cause clumping, reducing its effectiveness.
- Don’t use insulin that is discolored, frosty-looking, or that has clumps in it. Return it to the pharmacy for a replacement. Always inspect your insulin before you inject it. Clear varieties of insulin should always be clear, never cloudy or discolored.
Also, get in the habit of writing the date on your insulin vial or pen when you open it. This will help you to remember when to stop using it.
Diabetes is the most expensive chronic condition in the United States. Between 2014 and 2019, the average cost per unit of insulin rose 47% from $0.23 to $0.34, according to the website GoodRx. If you have trouble paying for your insulin, help is available here:
Also, let your healthcare provider know if you are struggling with the cost of insulin. There are less-expensive insulin options available that may work for you.
Want to learn more about insulin? Read “What Does Insulin Do?” “Insulin: What You Need to Know,” and “Insulin Basics.”