While much has been discussed about the dangers of exposing insulin to heat and the need to keep it refrigerated, the risks of insulin freezing are equally crucial to understand.

See, insulin is a temperature-sensitive injection that must be protected from extreme temperatures, whether hot or cold. And just like warm insulin loses its efficiency, insulin that has frozen isn’t good nor safe for use anymore.

So, today, this article finally addresses these important questions:

  • Can insulin freeze?
  • What happens if insulin freezes?
  • How to tell if it has frozen?
  • What are the risks of using thawed insulin?
  • At what temperature does insulin freeze?
  • How to keep insulin from freezing?
Insulin coolers and travel cases

Related article: Does Insulin Really Need to Be Refrigerated and How to Store it Properly?

Can You Freeze Insulin?

Despite lingering questions, the consensus is clear: insulin can’t be frozen. Across the board—doctors, drug manufacturers, pharmacists, and those with diabetes are unanimous. If your insulin has frozen, it's unfortunately not safe anymore and you shouldn’t use insulin that has frozen.

Related article: How to Keep Insulin Cool While Traveling?

What happens if insulin freezes?

What exactly happens when insulin freezes is a question that often comes up in discussions about insulin stability.Freezing temperatures are detrimental to insulin integrity and effectiveness.

Amin Zayani, an engineer and advocate for people with Type 1 diabetes, has spearheaded initiatives to safeguard temperature-sensitive medicines, and especially insulin. He actually calls the refrigerator "insulin frenemy”, explaining that “cold is really the one overlooked problem” with insulin. While insulin must be kept refrigerated, too much cold can be just as harmful as heat.

When insulin is frozen, it becomes unstable. The molecules form crystals, which is an irreversible change that disrupts their biological activity. This crystallization effectively breaks the insulin molecule, causing it to lose its effectiveness and potency. As a result, frozen insulin loses its capability to lower blood glucose levels efficiently, posing serious risks and side effects for your health. 

Related articleHow to Tell If Insulin Has Gone Bad?

Watch on video on the topic! 

Insulin Freezing Point

So, now the question is: at what temperature does insulin freeze? Understanding the freezing point of insulin is vital to diabetes management and proper insulin storage.  

As you know already, the temperature range is crucial when storing insulin. The recommended refrigeration range for unopened insulin pens, vials, and cartridges is between 36–46°F (2–8°C). After opening, insulin pens, cartridges, and vials are safe at room temperature, provided it doesn't exceed 77°F (25°C). 

The freezing point of insulin is the same as for water: 32°F (0°C). However, it is recommended to always maintain a buffer zone and keep your insulin stored safely above 36°F (2°C) to ensure it doesn't approach its freezing point. Remember that, just as for water, insulin can freeze in a few hours only.

Under no circumstances should insulin be stored at or below the freezing mark of 32°F (0°C), as this could lead to your insulin being accidentally frozen and rendered unsafe for use.

Related article: 8 Suprising Facts About Insulin You Did Not Know!

Is Insulin Still Good and Safe if it Freezes?

No, frozen insulin isn’t good or safe for use anymore. Using frozen insulin, even if it has frozen only briefly and it has thawed afterwards, can seriously affect your blood sugar levels and consequently pose risks to your health. But let’s dig a bit deeper and see what the drug manufacturers themselves say about it. It's pretty straightforward. All agree you should not use insulin that has been frozen.

Related articleHow to Dispose of Insulin Needles, Syringes, Pens, and Vials Safely?

“Do not use Novolog if it has frozen”

According to Novo Nordisk the manufacturer of Novolog fast-acting insulin aspart, Novolog should not be frozen: "Unused NovoLog® should be stored in a refrigerator between 2° and 8°C (36° to 46°F). Do not store in the freezer or directly adjacent to the refrigerator cooling element. Do not freeze Novolog and do not use NovoLog® if it has been frozen".

Related article: Does Novolog Need to Be Refrigerated and How to Store your Pens and Vials?

“Do not allow Lantus to freeze” 

According to Sanofi, the manufacturer of Lantus, Lantus long-acting insulin glargine can't be frozen either:  "Do not allow Lantus to freeze. Do not put Lantus in a freezer or next to a freezer pack. If you see frost or ice crystals in your Lantus solution, throw it away." 

Related article: How to Store Your Lantus Pens and Vials at Home.

“Do not use Humulin if it has frozen”

According to Eli Lilly, the manufacturer of Humulin, an isophane intermediate acting insulin, the same goes for your vials and pens "Storing the Humulin R U-500 vial: Do not use if it has been frozen.”.

And the same goes for all insulin types and brands, including, Apidra, Humalog, Novorapid, Tresiba, Levemir, Toujeo, and others. All insulin manufacturers firmly recommend not to use insulin that has frozen.

Related article: A Beginner’s Guide to Basal and Bolus Insulin.

Can You Use Thawed insulin?

Is thawed insulin still safe for use? The answer is resoundingly negative. If insulin has been frozen and returns to a liquid state, it should not be used. The initial freezing compromises the insulin's efficacy irreversibly, rendering it ineffective for blood sugar regulation, even if it has thawed afterwards.

The concern with thawed insulin extends beyond its reduced effectiveness. The structural integrity of the insulin is damaged during freezing, meaning it can no longer reliably perform its role in blood glucose management. Using thawed insulin can result in unpredictable and potentially dangerous blood sugar levels. 

Highlighting the seriousness of this issue, a case study published by the Postgrad Med  reports that a patient who defrosted accidentally frozen insulin with a microwave subsequently ended up in emergency care due to a total loss of blood sugar control.

This underscores the necessity of discarding any insulin that has been frozen, to prevent severe health risks.

Related articleDiabetes and Cold Weather, Managing Blood Sugar During Winter.

Insulin cooling cases with anti freeze security


How To Tell if Insulin Has Frozen?

Identifying frozen or thawed insulin is crucial for anyone relying on this medication for their diabetes management. So, if you find yourself in doubt of whether your insulin has frozen or not, there are fortunately a few signs to confirm your suspicions. Insulin that has frozen will exhibit distinct visual changes from its usual clear appearance.

Frozen insulin typically takes on a more solid and opaque appearance, similar to how water changes when it freezes. This transformation into a crystalline state is a clear indicator that your insulin isn’t good anymore.  When your insulin is frozen, you technically can't inject it, as it wouldn’t pass through the needle.

But it's a bit more complicated to tell if your insulin has frozen and then thawed. After it melts, your insulin gets back to its liquid state. In that case, look for changes in color and texture. Bad insulin generally looks cloudy, show clumps, or have white particles suspended in it—these are all indications that it may have been frozen. However, some insulin types are naturally cloudy, so make sure you know the natural appearance of your specific insulin.

Moreover, unusually high blood sugar readings could be an indirect sign that your insulin may have been compromised by freezing temperatures.

So, always be vigilant and if you have doubts, do not use the insulin. Instead, replace it with a fresh vial or pen from your refrigerator. The risks of using bad insulin far outweigh the benefits of using up what you have. Prioritize your health and well-being by ensuring the insulin you use is in optimal condition for effective blood sugar control. 

Related article: Can you Inject Cold Insulin Straight From the Fridge?

What to do if your insulin has frozen? 

Oops, has your insulin turned into an ice cube? And now what? What should you do with frozen or thawed insulin?

First off, even though it’s super tempting to just thaw it out and hope for the best, we’ve made it clear above that frozen insulin is a no-go for your health. So, it’s time to say goodbye to that vial or pen and dispose of it.

Insulin vials and disposable insulin pens can be thrown away in the regular trash. But don’t forget to remove the needle first as this one goes into a sharps container.  Unfortunately, these items do not recycle, and there’s generally no take-back program on insulin because of its delicate and strict storage instructions.

Related article: How Long Can a Diabetic Go Without Insulin?

How to Keep Insulin from Freezing?

You might be surprised how often insulin can freeze accidentally. Maybe there’s a power outage and your home loses heat during very cold winter days, or perhaps you forgot your insulin in the car overnight. Whether you’re traveling through cold climates or it just slips next to an ice pack in your medicine cooler, there are countless scenarios of accidentally frozen insulin. Here's how you can protect your insulin from freezing and save hundreds of dollars worth of medicine.

Never store insulin in or near the freezer

Typical domestic refrigerators do not maintain uniform temperatures like medical-grade fridges do. Temperature variations can be significant, especially near the freezer compartment or in the drawers, which tend to be the coldest parts of the fridge.

To ensure your insulin is stored safely and remains effective, place it on the middle shelf of your refrigerator. This area is least likely to get close to freezing temperatures and offers the most stable temperature conditions for sensitive medications like insulin.

Besides, you should absolutely avoid storing insulin in the freezer at all times. There is an exception, however: during a power outage, if your fridge stops working, you can temporarily store insulin in the freezer—but only if it has stopped running and there’s no alternative to keep it cold. This is a last-resort measure to prevent insulin from becoming too warm if the power is expected to be out for a prolonged period. 

Related article: How to Keep Insulin Cool Without Electricity or a Fridge?

Use your body heat to protect insulin in cold weather

Traveling to or living in a chilly climate? One of the simplest and most effective ways to keep your insulin from freezing is to use your own body heat. Keeping your insulin close to your body can naturally keep it at a safe temperature. Store insulin pens or vials in your inside jacket pockets, or even directly against your skin under your clothes for added warmth.

If you're using an insulin pump, remember that the insulin within the tubing and reservoir is also at risk of freezing! Insulin pumps like the Tandem T:Slim are designed with built-in temperature sensors to alert you if they become too cold. These sensors help ensure your insulin doesn’t freeze, no matter how cold the weather gets!

Ensure your insulin cooler has anti-freeze protection

When temperatures rise above 77°F (25°C), a portable insulin cooler becomes an essential item to protect your insulin from the heat. However, be cautious—some coolers may inadvertently freeze your insulin if not designed properly.

To avoid such risks, choose a cooler with built-in anti-freeze security. Products like those from 4AllFamily are engineered for safety. These travel medicine fridges utilize special crystals that freeze at 2°C / 35.6°F, slightly higher than the insulin’s freezing point at 0°C / 32°F. This clever design ensures that even if your insulin comes in direct contact with the cooling element, it always remains just above freezing!

Insulin coolers with anti freeze protection

Investing in a high-quality insulin cooler with these features can make a significant difference in maintaining the effectiveness of your insulin, providing peace of mind whether at home or on the go and regardless of whether it's summer or winter!

We'd Love to Hear from You!

Do you have tips or personal stories about dealing with frozen insulin? Share your experiences! How did you handle it, and what advice would you give to others in the same situation? Let’s learn from each other and build a supportive community!

Last updated on April, 25, 2024.

May 20, 2021


4AllFamily Customer Care Team said:

Dear Beveanne,
Don’t worry too much, as exposing insulin to room temperature for the time of the injection is absolutely fine. Insulin can stay at room temp for approximately a month (may vary depending on specific brands and types), so a few minutes out won’t lower its potency, as long as it stays under 25C/77F!
Best wishes,
4AllFamily Customer Care Team

Beveanne said:

In the whole world right now there is a heatwave.um I’m kind of hoping that exposing my insulin to room temp while injection is taking place isn’t enough to destroy it.all of our food is in the fridge.we only have a swamp cooler and the house stays 80-90.God must be real busy protecting diabetics right now because my strips still work and they won’t fit.

4AllFamily Customer Care Team said:

Hi Patricia,
Pharmacies and drug manufacturers are supposed to take all necessary measures to guarantee your insulin is shipped in the right temperature and storage conditions. Unfortunately, there’s no way to check and make sure it’s the case.
If you notice any unusually or unexplained high blood sugar levels while using this batch, it may be a sign your insulin has gone bad during transportation. In that case, immediately ask for your doctor’s advice.
We hope it won’t happen!
Best regards,
4AllFamily Customer Care Team

Patricia Biddle said:

I am concerned because I get a 90 day supply shipped to my home according to insurance protocol. My insulin comes in a box with ice packs directly over and under the insulin bottles…The insulin is received with it laying directly on the ice packs for hours or days during shipping. How am I to know if it is still viable or not? I have heard horror stories about medications laying on tarmacs for hours in in extreme temperatures and there is no way of knowing how they were stored or transported from a customers standpoint. Thanks

4AllFamily Customer Care Team said:

Hi Kevin,
Thank you for sharing your experience with us! We are glad to hear that it worked for you, but we must advise that using frozen insulin can be dangerous for your health.
When insulin is frozen, it can lose its effectiveness and potency, which can result in high glucose levels. This is against the manufacturer’s recommendations, and we strongly advise against it.
Insulin can be very expensive. However, compromising your health and well-being is not worth the risk.
Thank you for reaching out to us.
Best regards,
4AllFamily Customer Care Team

Kevin Harris said:

Can I tell my story? I live in England but am in the US for a weeks holiday. When I arrived I accidentally put my Lantus insulin in the freezer (the freezer was at the top instead of at the bottom as you would except and I wasn’t concentrating). I googled it and everywhere I read it said that frozen insulin is only good for the ‘trash’. It says on many websites that it won’t hurt you but it just won’t work, so I looked around in NYC and the cost of one vial was around $250…eek. So I thought before I replace it I would give it a go. Well it turns out that it works fine. Maybe it’s just me it worked for. Everyones different right? And I don’t recommend freezing your life saving liquid, but I think in an emergency situation you should be ok!

4AllFamily Customer Care Team said:

Hi Daniela,
Thanks for sharing your experience with us. Insulin storage and transportation aren’t that simple and there’s a lot of unfortunate events occurring to patients.
Cooler bags with gel packs like the one you’ve used are not recommended for insulin, even though manufacturers say they are. Temperatures drop too fast in there and there’s no guarantee it’s 100% efficient as any hole could let warmer air enter.

4AllFamily Customer Care Team said:

Hi M. Rutherford,
Thank you for your comment and interesting point. We do not have detailed information about “how much” less effective the insulin is after freezing. There’s very little research available on the topic. Besides, insulin loses its potency gradually, so the answer probably varies depending on the temperature it has reached as well as how long it has been frozen for (we suppose).
Similarly, it would be logical that there’s a difference between storing insulin at 2C or at 8C. However, we’re not qualified to answer here, as we have not conducted any research ourselves and could not find any reliable one either.
We’re sorry not to be able to give you a better answer. We’ll definitely get back if we find it!

4AllFamily Customer Care Team said:

Hi Lorraine,
We’re glad you’re now safe. Using insulin that has frozen can be dangerous, especially for type 1 diabetics that can quickly go into DKC. Thanks for sharing your experience with our readers, it will help raise awareness!

Daniela said:

I had actually two temperature related experiences…
Situation 1)
normal household fridge, insulin in the original “for a month” supply cardboard box… Cardboard too close to the back of the fridge (not the cooling element one shelf up and at the side)… Insulin in the last two pens at the back of the box was frozen and thereby useless.
Situation 2)
summer, 32 Celsius, travel by train for 6h, to my “stay for 2 month” destination… Full insulin stash in backpack in a little “for insulin, big red cross on it” cooler bag with two big gel packs… Supposed to keep it cool for up to 24h… “Up to” being verrrry optimistic.
Started with fridge temperature insulin 6 degrees Celsius…
Temperature when I reached destination (actually 8h of cooling) 22 degrees Celsius.
Gone was my quarterly stash.

M. Rutherford said:

interestingly the article references “ It won’t be lowering your blood sugars anymore- or not as much as it should.” but does not give details about her ‘not as much as it should be’ actually means. Is it half as effective a quarter as effective.

Additionally the example of frozen insulin that is sited has the gentleman using a microwave to unfreeze the insulin. I’m pretty sure microwave radiation isn’t good for insulin period.

If you have details on what percentage of insulin remains after freezing or deep freezing I would love to hear it. The manufactures are always going to press for getting new stuff based on 100% efficacy and on the worst of the storage data they have. 8 Celsius vs. 9 was the demarcation. Do you think 2 vs 8 didn’t see any difference?

Lorraine hyland said:

I was on holiday in Spain and the fridge was faulty. I am 46 years a type 1 diabetic. I unknowingly used thawed insulin and became seriously ill within 24 hrs going into DKC. Thankfully we worked it out bought a small portable fridge for the remainder of our holiday and got fresh insulin in the Spanish pharmacy. I am Irish. I broughtmy passport and E111 with me and the whole event including hospitalisation treatment and replacement insulin cost me 15euro. This is available to eeu citizens

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The information presented in this article and its comment section is for informational purposes only and is not intended as a replacement for professional medical advice. Always consult with a qualified healthcare provider for any medical concerns or questions you may have.