Lots have been written about insulin and heat. Still, little information is available as to what happens to insulin when it freezes? Insulin should never be exposed to extreme temperatures, whether hot or cold. Just like warm insulin loses efficiency, insulin that has frozen is not safe for use anymore. Your injectables have to be stored cold. But how cold can insulin get? Can you still use insulin vials or pens that have frozen? What would the consequences be? Let's answer all of your questions here!

4AlLFamily Insulin Coolers with Anti-freeze security

Can you freeze insulin?

If the question has been left unanswered for quite a long time, there's no more doubt: you can't freeze insulin. Doctors, drug manufacturers, pharmacists, diabetes patients, biologists… everybody agrees that frozen insulin is good for trash.

Related article: Does Insulin Need to Be Refrigerated and How to Store Your Pens & Vials Correctly?

What happens if insulin freezes?

Freezing breaks down insulin. Amin Zayani is an engineer living with Type 1 diabetes. He has led successful projects to protect temperature-sensitive medications. He calls the refrigerators "insulin frenemy," saying "cold is really the one overlooked problem" with insulin. In this video, he explains very well what happens to insulin if it freezes.

When frozen, the solution becomes crystals. These crystals break the molecule. As a result, insulin loses its properties, capacities, and efficiency. It won't be lowering your blood sugars anymore- or not as much as it should.

Related article: How to Tell If Insulin Has Gone Bad?

So, how cold can insulin get?

The temperature-sensitive hormone must be protected from extreme temperatures. When stored, your stocks of insulin must be refrigerated between 36–46°F (2–8°C). Once open, your pens, cartridges, and vials can stay at room temperature for about a month but should not be exposed to temperatures over 77°F (25°C).

Insulin is a protein dissolved in water. Insulin freezing point is at 32°F (0°C), just like water. To maintain a safety margin, you should always keep your insulin above 36°F (2°C). In any case, insulin should never be stored under 32°F (0°C).

During winter keep insulin close to body warmth

Is frozen insulin still good?

No. Frozen insulin does not work anymore. Injecting frozen insulin, even if it has thawed, can seriously affect your diabetes management. Let's see what the drug manufacturers themselves say about it.

Related article: How to Dispose of Insulin Needles, Syringes, Pens, and Vials Safely?

Can you use frozen insulin?

Apart from the fact that you would technically not be able to inject frozen insulin, it's absolutely recommended you do not. I've been investigating a bit more and checked what the leading manufacturers say about frozen insulin. It's pretty straightforward. All agree you should not use insulin that has been 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"


"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."


"Storing the Humulin R U-500 vial: Do not use if it has been frozen."

You should verify specific rules for the insulin you're using. Apidra, Humalog, Novorapid, Tresiba, Levemir, Toujeo, etc, all firmly recommend not to use insulin that has frozen, even if it has thawed afterward.

What about thawed insulin?

What if your insulin has frozen but is now back to its liquid state? You shouldn't use it either. The mere fact that it has frozen, even briefly, makes your insulin good for nothing else but the garbage.

The freezing process has already broken down your insulin, and you would inject yourself a hormone that's not working. Your blood sugar levels won't lower. Worst, they'll get uncontrollable!

Westminster Medical School published an interesting case study. A 28 years old man thawed his accidentally frozen insulin with his microwave defrost mode. He subsequently ended up in emergency care due to a total loss of blood sugar control.

Related article: Diabetes and Cold Weather, Managing Blood Sugar During Winter.

How to tell if your insulin has been frozen?

If you suspect your insulin might have frozen, you should carefully scrutinize it. Some signs clearly indicate that your insulin is not good anymore.

What does frozen insulin look like?

It looks frozen! Insulin freezes like water do. It becomes solid and opaquer. When your insulin is frozen, you technically can't inject it. It would not pass through the needle.

It's more complicated to tell if your insulin has frozen and then thawed. After it melts, your insulin gets back to its liquid state. Look for changes in color and texture. Bad insulin looks cloudy (unless it's a naturally-cloudy type of insulin!). It's often clumpy, and you can see little white strings and particles.

Unusually high glucose levels can also be a sign that there's something wrong with your insulin.

Frozen insulin looks cloudy

Related article: What is Mounjaro and How Does it Work For Diabetes and Weight Loss?

What to do if your insulin has frozen?

Insulin that has frozen is not safe to use. Do not try to thaw it. The side effects of using insulin that has frozen can be severe. You should immediately throw your insulin away and get a new vial or pen.

How to prevent your insulin from freezing?

Situations where your insulin might accidentally freeze are much more common than you'd think: a power outage leaves you without heating; you've forgotten your insulin in your car overnight; you live or travel in icy places; you've put your insulin in direct contact with your medicine cooler's ice packs. There are dozens of situations where it could happen. Here's how you can protect your insulin from freezing and save $$$ worth of medications.

Store your insulin in the right fridge compartments

Domestic fridges do not follow the same standards as medical fridges. The temperature is not the same everywhere in your fridge, and it actually varies quite a lot. The fridge zones that are closer to the freezer compartments are at risk of freezing temperatures. The vegetable, meat, and fish bottom drawers are often the coldest zones too. The ideal place to keep your insulin safe from freezing is your fridge's middle shelf. It's the one that risks no freezing and has the most stable temperature.

Of course, never keep your insulin in the freezer. In case of a power outage, we do recommend storing your insulin in the freezer, but it's only in case it's out of power!

Store insulin on the fridge middle shelf

In cold weather, keep your insulin close to your body

Suppose you're traveling to or living in a cold-weather destination. The best way to prevent your insulin from freezing is to keep it close to your body. Your body warmth should be enough to keep it safe. Place your insulin pens or vials in your inside pockets or even in direct contact with your skin.

The same applies if you're wearing an insulin pump. The insulin in the tubings and reservoir could freeze if the ambient temperature is cold. Some insulin pumps like the Tandem T:Slim are equipped with temperature sensors that warn you when the pump gets too cold.

In warm weather, choose an insulin cooler with anti-freeze security

Insulin also has to be protected from the heat and should never be exposed to temperatures over 77°F (25°C). Whenever the ambient temperature is higher than that, you should equip yourself with an insulin cooler. The problem is that poorly constructed insulin coolers might freeze your insulin!

Fortunately, some portable medicine fridges come with anti-freeze security, like the ones from 4AllFamily!  Our crystals freeze at 2°C / 35.6°F, while insulin freezes at 0°C / 32°F. It does prevent your insulin from freezing, even if it's in direct contact with the frozen pack. 

4AllFamily Insulin Travel Coolers

Share your bits of advice and experiences too! Have you ever had to deal with frozen insulin? What did you do?

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

Leave a comment

Please note: comments must be approved before they are published.