Quick Answer: No, insulin should never freeze. If it's exposed to temperatures below 0°C and freezes, it becomes ineffective and unsafe to use. To prevent this, always store insulin as recommended and avoid placing it near freezers or in freezing conditions
While much has been discussed about the dangers of exposing insulin to the South African 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 or 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?
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 article: How 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 2-8°C. After opening, insulin pens, cartridges, and vials are safe at room temperature, provided it doesn't exceed 25°C.
The freezing point of insulin is the same as for water: 0°C. However, it is recommended to always maintain a buffer zone and keep your insulin stored safely above 2°C to ensure it doesn't approach its freezing point. Remember that, just as for water, insulin can freeze in a few hours.
Under no circumstances should insulin be stored at or below the freezing mark of 0°C, as this could lead to your insulin being accidentally frozen and rendered unsafe for use.
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 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 article: How 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. 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"
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."
"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.
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 accidentally defrosted 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.
How To Tell if Insulin Has Frozen?
Identifying frozen or thawed insulin is essential for safe diabetes management. If insulin has been exposed to cold temperatures, you may need to check for signs of freezing. Since frozen insulin becomes ineffective and unsafe to use, here's how to identify if your insulin has been compromised:
- Solid or opaque appearance - Insulin that has completely frozen may look cloudy, solidified, or crystallized.
- Clumps or white particles - If thawed, previously frozen insulin may contain visible clumps or suspended particles.
- Injection issues - Fully frozen insulin won't pass through a needle, making it impossible to inject.
- Unusual blood sugar levels - If your blood sugar readings are unexpectedly high, your insulin may have lost effectiveness due to freezing.
- Texture and color changes - Some insulin types are naturally cloudy, but if yours looks different than usual, it could indicate freezing damage.
If you suspect your insulin has frozen, do not use it. Instead, replace it with a fresh vial or pen to ensure safe and effective blood sugar control. The risks of using compromised insulin far outweigh the cost of replacing it.
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..
In South Africa, expired or frozen insulin should never be thrown in the bin. Instead, it must be returned to a pharmacy, where it will be disposed of following medical waste regulations. Do not attempt to recycle it or pour it down the drain.
Remember to also place any used needles or sharps into a proper sharps container (or a puncture-proof container like a sealed plastic bottle) and take those to the pharmacy too. Most pharmacies will accept them and handle the disposal safely and legally.
How to Keep Insulin from Freezing?
Insulin can freeze more often than you might expect, sometimes without you even realizing it. The cold temperatures of South African winter in the country's interior can quickly render it ineffective, leading to health risks and wasted medication. Here are some common scenarios where insulin may accidentally freeze:
❄️ Power outages in winter - Loss of heating can cause indoor temperatures to drop below freezing.
🚗 Leaving insulin in a car overnight - Vehicles can get extremely cold during winter, freezing insulin left inside.
✈️ Traveling through cold climates - Exposure to freezing temperatures can compromise insulin if not properly insulated.
🧊 Storing insulin near a freezer compartment - Household refrigerators have cold spots that may accidentally freeze insulin.
🥶 Placing insulin next to an ice pack in a cooler - Direct contact with ice packs can cause insulin to freeze.
📦 Shipping delays in winter - Insulin deliveries left in freezing conditions during transit may arrive frozen.
👉 Next: Let's go over key precautions you can take to prevent insulin from freezing and keep it at a safe temperature at all times.
Never store insulin in or near the freezer
Proper insulin storage is essential to maintaining its effectiveness. Unlike medical-grade fridges, household refrigerators have temperature fluctuations that can put your insulin at risk of freezing. Storing it in the wrong place-like near the freezer-can lead to irreversible damage. Follow these guidelines to ensure your insulin stays safe:
✅ What to Do:
- Store insulin on the middle shelf of the fridge - This area maintains the most stable temperature.
- Keep insulin between 2-8°C - This is the recommended safe storage range.
- Use an insulated container if needed - Helps protect insulin from sudden temperature changes.
- Monitor fridge temperatures - Consider using a thermometer to ensure consistency.
❌ What Not to Do:
- Never store insulin in or near the freezer - Cold spots in a regular fridge can freeze insulin.
- Avoid keeping it in fridge drawers - These areas are often colder and prone to freezing.
- Do not store insulin directly against cooling elements - These spots can dip below safe temperatures.
- Only place insulin in a non-working freezer as a last resort - This should only be done during power outages when no other cooling options are available.
By following these simple storage rules, you can prevent accidental freezing and ensure your insulin remains effective for blood sugar control.
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 25°C, a portable insulin cooler becomes an essential item to protect your insulin from the heat. However, be cautious that 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, slightly higher than the insulin's freezing point at 0°C . This clever design ensures that even if your insulin comes in direct contact with the cooling element, it always remains just above freezing!
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!
📌 Key Takeaways:
✅ Insulin Freezes at 0°C - Just like water, insulin can freeze at this temperature, making it completely ineffective.
🚫 Frozen Insulin is Unsafe - Once frozen, insulin undergoes irreversible changes and should never be used, even if thawed.
❄️ Common Causes of Freezing - Power outages, leaving insulin in a car, cold travel conditions, or storing it near freezers/ice packs can all lead to accidental freezing.
🔎 Signs of Frozen Insulin - Cloudy appearance, clumps, or unusual blood sugar spikes could indicate that insulin was compromised by freezing.
🛡 Prevent Freezing with Proper Storage - Keep insulin between 2-8°C, avoid cold spots in the fridge, use body heat in winter, and choose coolers with anti-freeze protection.
💬 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!
