Can You Freeze Insulin: What Should You Expect?

No, insulin should never be frozen—doing so makes it ineffective and potentially dangerous. Frozen insulin cannot be safely injected and won’t properly control blood sugar levels, even after thawing. To preserve potency, store unopened insulin between 36 °F and 46 °F (2 °C and 8 °C) in the refrigerator and opened insulin at room temperature (59 °F to 86 °F or 15 °C to 30 °C) for up to 28 days, depending on the type.

Signs of spoiled insulin include cloudiness, discoloration, or particles. To avoid freezing, never store insulin near freezer elements or leave it in cold environments. Use insulin coolers with anti-freezing protection or carry it close to your body during winter travel. Safe storage is essential to prevent diabetes complications and ensure reliable blood glucose control.

Key Takeaways

• Frozen insulin becomes ineffective and should never be used—even if it thaws.
• Unopened insulin should be refrigerated at 36 °F to 46 °F (2 °C to 8 °C).
• Opened insulin can stay at room temperature (59 °F to 86 °F / 15 °C to 30 °C) for up to 28 days.
• Do not store insulin near freezers, freezer packs, or leave it in cars during cold weather.
• Spoiled insulin may appear cloudy, discolored, or have particles—do not use it.
• Use insulin coolers with anti-freezing properties or keep insulin close to your body in cold weather.

Does Insulin Need to Be Refrigerated?

Top U.S. insulin drug manufacturers recommend storing unopened insulin in refrigerators at approximately 36 °F (2.22 °C) to 46 °F (ca. 8 °C). This storage condition must be met for the insulin product to maintain its potency until the expiration date on the package. Never store your insulin in a freezer or other freezing places.

You can store/use unopened and opened inulin vials or cartridges unrefrigerated for 28 days, provided you keep them at temperatures ranging from 59 °F (15 °C) to 86 °F (30 °C).

What Happens if Insulin is Not Refrigerated

Although insulin (open or unopened) can stay unrefrigerated at room temperature for up to 28 days, unopened insulin loses some of its properties, capacities, and potency when exposed to high temperatures, usually above 36 °F (2.22 °C) to 46 °F (ca. 8 °C).

The longer your insulin is stored at such a temperature, the less effective it becomes, ultimately resulting in its inability to stay potent until the expiration date printed on the insulin box.

Injecting damaged or expired insulin can make it harder to control your blood sugar levels, putting you at a higher risk of diabetes-related complications, including hyperglycemia, nerve damage, kidney damage, eye damage, and skin and mouth conditions.

Can You Use Frozen Insulin

No, freezing insulin is not advisable! Throw frozen insulin into the trash and get a new vial or pen reservoir.

The top three drug manufacturers in the US that produce insulin clearly state that any insulin stored below 36 °F (2.22 °C) will freeze. Frozen insulin can’t pass through the needle and can’t be injected in its frozen state. Even when it thaws, it can’t regulate your blood sugars because the freezing temperature has already impaired the protein.

To ensure your insulin is safe, protect it from icy cold weather, such as during snowboarding. If you must store your insulin vial or pen in a fridge, keep it closer to the door, where it is less likely to get frozen, or better still, get an insulin cooler.

What Are Manufacturers Saying About Frozen Insulin

It’s always necessary to check out the manufacturer’s instructions before taking any insulin injection. Here are the recommendations by renowned insulin manufacturers on what to do with frozen insulin:

Humulin

The package instructions read:

Storing the Humulin R U-500 vial: Do not use the vial if it has been frozen. Like other insulins such as Humalog, Levemir, Novorapid, Toujeo, Apidra, and Tresiba, Humulin R U-500 becomes ineffective once frozen.

Novolog

The manufacturer’s instructions are as follows:

Keep unused NovoLog® in the refrigerator between 36 °F (2.22 °C) and 46 °F (ca. 8 °C). Do not place it in the freezer or near the refrigerator’s cooling element. Never freeze NovoLog®, and do not use it if it has been frozen.

Lantus

The manufacturer recommends the following storage conditions:

Do not let Lantus freeze. Never place it in a freezer or next to a freezer pack. If you notice frost or ice crystals in the solution, dispose of it immediately.

How Can I Tell if My Insulin is Spoiled

The most common way to identify damaged insulin is if you notice a change in its color or overall appearance. If, for instance, your clear insulin suddenly becomes cloudy or discolored or has particles or crystals, then it’s probably spoiled.

Insulin types and changes indicating they are damaged:

• Lispro, Aspart, and Glargine: These are bright-colored insulin products, so if you observe any color change, cloudiness, or floating particles, it could be a sign of contamination or a damaged product.
• NPH (Neutral Protamine Hagedorn): This type of insulin is naturally cloudy; however, if you find a tiny white clump at the bottom of the bottle or a “frosting” appearance on the inside wall of the glass vial, throw away or return to the seller, manufacturer, or distributor.

How Do I Identify Frozen Insulin?

Frozen insulin, like any frozen liquid, becomes solid and opaque, meaning that it cannot be injected.

It’s a bit trickier to identify frozen but thawed insulin. This is because the thawing process returns icy insulin to a liquid state.

If you suspect your insulin might have frozen initially but is now in liquid form, scrutinize it for changes in colors and textures.

How to Store Insulin

Most cases of damaged insulin are due to poor storage. “Too hot” or “too cold” is not an option when it comes to insulin storage.

The proper way to store your insulin meds depends on the brand or type. For instance, an insulin vial’s storage recommendation differs from an insulin pen, and that of a vial or pen is not the same as that of an insulin pump.

Insulin vials

You can store unopened insulin vials in the fridge until their expiration date. Most opened insulin vials last up to 28 days with or without refrigeration. However, some products last more than 28 days outside the fridge. Examples are Human insulin (Humulin N), Insulin detemir (Levemir), and Insulin Degludec (Tresiba).

Insulin pump

The instructions for using or storing insulin pumps may differ from what is written on the box. So, if you use a pump, always read its storage instructions. If the instructions on the pump and box are different, follow the stricter instructions, requiring the shortest number of days for a change of insulin.

The standard recommendations for pump storage:

• Insulin Lispro (Humalog) — 7 days.
• Insulin Aspart (NovoLog) — 7 days
• Insulin Aspart (Fiasp) — 6 days
• Insulin Glulisine (Apidra) 48 hours

Insulin pens

You can refrigerate your unopened insulin pens to keep them safe until their expiry dates. However, unlike insulin vials, you must not store your pens in a fridge once they are open.

The best condition is to keep them at room temperature, remove the needles to prevent contamination, and cover them with caps to protect them from light.

For pens, most open and unopened insulin stored outside the fridge will stay effective for 28 days if you stick to the conditions above.

Other products (open or unopened) may stay less or more than 28 days at room temperature. Examples are:

• Humulin N Kwikpen — 14 days.
• Insulin detemir (Levemir FlexTouch) — 42 days.
• Insulin degludec (Tresiba FlexTouch) — 56 days.

Insulin mixes

Insulin mixes are pre-mixtures of different insulins, mainly containing 70–75% intermediate-acting insulin and about 25–30% rapid or short-acting insulin. Unopened insulin mix vials and pens can be refrigerated until their expiry date.

Most opened insulin mix vials can be stored inside the fridge or at room temperature for 28 days. Examples are Insulin Lispro 75/25 and 50/50 (Humalog 75/25 and Humalog Mix 50/50) and Insulin Aspart 70/30 (NovoLog
Mix
70/30). Although, Humulin 70/30 can last up to 31 days.

Open mixed insulin pens must not be refrigerated. Once opened, some can last for 10
days at room temperature — an example is Insulin Lispro Pen (Humalog Mix 75/25 and Humalog Mix 50/50). Others can stay up to 14
days at room temperature — an example is Insulin Aspart Pen 70/30 (NovoLog Mix 70/30)

How to Prevent Your Insulin From Freezing

Many people with diabetes find it more challenging to keep insulin safe during winter than in summer. For instance, you can guarantee your insulin’s safety by putting it inside a portable medical fridge — even under the scorching summer sun. However, the same can not be said about an accidental power outage during winter with no means to warm your room. You may find it hard to stop your insulin meds from freezing in such situations!

So, how do you protect your insulin from cold weather?

• Don’t expose your insulin to the cold weather outside during winter.
• Don’t forget your insulin supplies in the car overnight when temperatures outside are freezing.
• Use the right fridge compartment to store insulin in your home fridge during summer. Or better yet, use an insulin cooler or a portable medical fridge for the best result.
• Do not put your insulin in a freezer.
• If you are outside hiking or snowboarding in freezing winter weather, always keep your insulin close to your body. I recommend using your inside pockets or keeping the insulin vial, pen, or pump in direct contact with your skin.
• Always go for insulin coolers with anti-freezing properties.

Conclusion

When temperatures are out of control, your blood sugar will likely follow suit. Hot or cold weather extremes can affect your diabetes medications and injectables, making it difficult to control sugar levels and prevent diabetes complications.

A 2018 study indicated a sharp rise in hospitalizations among diabetics when temperatures hit extreme highs or lows (during summer and winter). Hence, to keep your blood sugar under control, it’s pertinent to know the storage recommendations for your insulin meds and stick to them.