Can Insulin go bad? How to tell and what to do if it has?

Bad insulin is something that worries more than 7 million people in the US only. That's the approx. number of Americans with diabetes using insulin. Every single one of them worries insulin might go bad and he or she might get sick or lose hundreds of dollars worth of medication. 

The truth is insulin can go bad, and it often will if you’re not careful. But a few basic commonsense measures are enough to keep your medicine safe and efficient. Let’s dive in and answer all your questions.

Can Insulin Go bad?

Yes, insulin can go bad. Insulin often goes bad. It's a hormone that's highly sensitive to temperature conditions. If not stored properly, if exposed to extreme temperatures and temperature changes, or if its expiration date has passed, insulin goes bad.

Note: all types and brands of insulin can go bad. Novolog, Lantus, Humulin, Humalog, Novorapid, FIASP, Novolin, Levimir, Apidra, Tresiba, Basaglar, Toujeo, etc. 

Insulin storage recommendations

Insulin storage recommendations are rigorous but clear. In general, unopened insulin vials, pens, or cartridges must be stored at fridge temperature – between 36°F (2°C) and 46°F (8°C) - until the expiration date appended by the manufacturer. Once opened or out of the fridge, insulin is stable for about a month at room temperature - between 56°F (13°C) and 80°F (26°C). If these storage rules aren't followed properly, your insulin can go bad.

Related: Victoza storage: what really happens if Victoza is not refrigerated?

Related: Why does Trulicity need to be refrigerated?

Related: How to properly store and refrigerate Ozempic in all situations?

Heat can make insulin go bad

Heat is what most often makes insulin go bad. If exposed to temperatures above 80°F (26°C) for extended periods, or if exposed to very high temperatures for a few seconds only, your insulin can spoil very fast.

Freezing temperatures can also break insulin 

Watch out for cold temperatures as well! Insulin is a protein dissolved in water, and just like water, its freezing point is at 32°F (0°C). The freezing process breaks down the insulin which would lose its potency even if thawed afterward. To maintain a safety margin, you should always make sure your insulin is kept above 36°F (2°C).

Related: Can you freeze insulin and what really happens if you do?

Insulin has two expiration dates

It’s true, insulin has two different expiration dates you should keep track of. The one printed on the product by the manufacturer. And the one arriving about a month after you first opened your insulin or took it out of the fridge.

In both cases, past the expiration date, the stability and potency of your insulin are not guaranteed anymore. Do not take any chances. Dispose of it immediately and open a new one.

Note: insulin’s stability once opened or out of the fridge slightly varies depending on the brand you’re using. Some insulins are good for only 28 days once opened (Lantus, Novolog, Humalog, Apidra, Basaglar), while others can last up to 31 days (Humulin), 42 days (Novolin, Levemir, Toujeo), or even 56 days (Tresiba).


Insulin storage temperatures

Insulin expiration dates slightly vary depending on the brand

Do bad batches of insulin happen?

It should not. In theory, laboratories’ security and safety measures are such that bad batches of insulin are extremely rare. Everything is planned and done so the insulin is safely stored from the moment it leaves the laboratory until it’s given to you at the pharmacy.

But to err is human. A few years ago, Novo Nordisk had to recall bad batches of insulin cartridge holders. If very unlikely, a breach in the cold chain could also happen and create a bad batch of insulin. In any case, always inspect your new insulin pen, vial, or cartridges before using them.

Exposure to light can damage your insulin

Insulin is a protein, and like any protein, its exposure to light may cause photodegradation and make it lose its properties. That's why your pen top cap is opaque. It protects the liquid inside from light.

To protect your insulin from light, always keep the cap of your pen on, and never leave your vials in the direct sunlight. That should be enough.

Contaminated insulin is a low risk

Biological contamination of insulin pens or vials is rare but can happen. After using your injectable pen, immediately remove the needle so air and bacteria can’t enter the device and contaminate the liquid. You should never share an insulin pen with someone else, even if you change the needles.

Air bubbles could ruin your insulin pens or vials

Another scenario is if you're insulin pen or vial is suddenly full of air bubbles. The insulin has not gone bad, but you'd be injecting air instead and your blood sugars won't lower. This can happen if your pens, vials, or cartridges have been strongly shaken, or if you're taking the plane with them. While on the plane, always prime your pens after take-off and landing to evacuate the air bubbles before injecting.

Related: Can insulin pumps go through X-ray and metal detectors at the airport?

Related: TSA regulations for diabetics: traveling with diabetes supplies and insulin.

How to tell if insulin has gone bad?

You suspect your insulin has gone bad? You feel like something isn’t right. You can usually tell if you’re insulin has gone bad by visually inspecting it. Unexplained high blood sugar levels are also a sign you might be injecting bad insulin. In any case, if you have doubts, try out new insulin from out of the fridge. 

Visual inspection can tell if insulin has gone bad

Most insulins are water-like liquid medicines that are clear and colorless. A visual inspection usually allows you to tell if your insulin pens, cartridges, or vials have gone bad. If you notice a change of color, if it looks cloudy, or if you find clumps, strings, or frost inside, it's gone bad. Immediately throw it away. Do not use insulin that does not look like it should. 

How to tell if insulin has gone bad?

Note: Novolin N, Humulin N, Insulatard, and others are NPH (Neutral Protamine Hagedorn) type of insulin. They are naturally cloudy. However, if you see clumps at the bottom of the bottle, white coating, or frosting on the inside, it's a sign it has gone bad and you should not use it.

Unexplained high blood sugars are signs your insulin might be bad

Another sign that your insulin might have gone bad is if you're experiencing unexplained and unusually high blood sugar levels. Injecting bad insulin that has lost the totality of its potency is like injecting water: it’s useless and won’t lower your blood glucose levels.

Unexplained and unusual high sugar levels should always alarm you to inspect your in-use insulin. If you can, take a new pen or vial from your fridge for the next injection. If your sugars go back to normal, you can conclude the old insulin was bad and throw it away. If your blood sugars aren't back to normal levels, call your doctor for advice. Do not stay with high blood sugar levels for an extended time, it's dangerous.

How to prevent your insulin from going bad?

Fortunately, there are many commonsense measures you can take to protect your expensive medicine and prevent your insulin from going bad. After all, there's nothing more infuriating than losing hundreds of dollars worth of medication because of your own fault. Here's what you can do:

Conscientiously follow insulin storage instructions

As we've seen above, insulin storage instructions are quite rigorous, but they're absolutely necessary. Remember that your insulin pens, vials, or cartridges must be kept in the fridge - between 36°F (2°C) and 46°F (8°C) until you first open them. Once opened, they’re good for about a month at room temperature -between 56°F (13°C) and 80°F (26°C).

While in the fridge, be sure your insulin isn’t near the freezing compartment and is safe from freezing hazards. Never leave your insulin pens or vials in the car overnight if it gets below 36°F (2°C).

During that month at room temperature, be sure your insulin never gets exposed to very high temperatures. Don’t leave it in the car during a hot summer day. Don’t put it near the stove or fireplace even for a few seconds. Of course, never put your insulin in the microwave.

Related: How to keep insulin cool during a power outage and without electricity?

Use an insulin cooler if necessary

If you’re living in or traveling to places where the outside temperature gets above 80°F (26°C), you need a cooling solution for your in-use insulin.

You could DIY a cooler with an insulated lunch bag and a few ice cubes. It's not the safest solution though, as you have no means to check the inside temperature and be sure your insulin is cool enough.

The most convenient solution for temperature-sensitive medicines like insulin is to get an actual medicine cooler. At 4AllFamily, we've spent the last few years designing the ideal travel coolers for medications and we're pretty proud of what we came out with!


Our ice-free coolers can keep your insulin cool in any situation, whether you have access to electricity or not. Lightweight and portable, they're TSA-approved so you can board the plane with your medicine.

Related: Camping with insulin: diabetes supplies, snacks, and insulin coolers

Protect your insulin from freezing

On the contrary, suppose you’re living in or traveling to a freezing cold destination. You’d need to protect your insulin from freezing or it would break down and lose its potency. When outside, keep your insulin in your inside pocket. Your body's warmth should be enough to prevent it from freezing. Of course, never leave your insulin outside.

If you use an insulin cooler for hot weather, be sure it has an anti-freeze security. Some coolers that are not specially designed for medicines can reach very low temperatures that could freeze your insulin. 4AllFamily’s medical-grade coolers all guarantee your insulin can’t freeze.

Related: Can you freeze insulin and what really happens if you do?

Use a sanitary cap for your insulin vials 

To prevent dust and bacterial contamination of your insulin vials, you can use a sanitary cap. 4AllFamily has designed the only insulin vial protector that not only prevents your vials from breaking in case of fall but also protects the surface of your vial against dust and bacteria!

4AllFamily's insulin vial protector with a sanitary lid

What to do if your insulin had gone bad?

Despite all measures you’ve carefully taken, your insulin has gone bad. Don’t panic. It happens to diabetics every day. The important point is that you’ve noticed your insulin is bad and you’ve stopped using it.

Immediately dispose of bad or expired insulin

The first thing to do is to dispose of bad insulin, so you're sure you won't use the bad pen or vial anymore. Your expired or bad insulin could still be biologically active. To avoid accidents with children or pets, you must dispose of it properly.

Unused insulin vials should be disposed of in a container for biohazardous and regulated medical wastes. Insulin pens should be disposed of in sharps containers along with the needles.  

Call your insulin manufacturer or pharmacist

Some insulin manufacturers have helpful troubleshooting programs that might replace your bad insulin (depending on the reason why it's gone bad). It's the case for example for Novo Nordisk, or Sanofi. Your pharmacist might also be able to help you out, depending on their refund and return policies.

Can bad insulin make you sick?

Finally, an often-asked question: can bad insulin make you sick? If your insulin is bad as "not efficient" anymore and you inject it, it should not make you sick. However, it won't lower your blood sugar, and you risk unusual high levels for an extended period of time (hyperglycemia) which could ultimately lead to a Diabetic Ketoacidosis coma.

If you inject insulin that's bad because it has been contaminated, you could get sick. However, this scenario is extremely rare.

We hope you’ve found the answers you were looking for. Please, share your stories and experiences with us. Have you ever had to deal with bad insulin?

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