Quick Answer: An unopened insulin vial lasts until its expiration date if refrigerated. Once opened, it remains effective for about 28 to 42 days at room temperature. Most people with diabetes use 2-3 vials per month, depending on their prescribed daily dosage.
Insulin is a hormone produced by the pancreas which regulates the amount of glucose in the blood. When the natural production of insulin is disrupted, or the insulin produced isn't effective enough, the level of sugar in one person's blood is too high. This person has diabetes.
Science has managed to create animal-derived and synthetic insulins to mimic the action of natural insulin in the treatment of both type 1 and type 2 diabetes. There are different types of pharmaceutical insulins, and they may come in different containers such as vials, self-injectable pens, or cartridges.
Let's focus here on insulin vials and find out more about them. How much insulin is inside? How to store your vials? How many do you need per month? How much do they cost?
How long does a vial of insulin last?
How long a vial of insulin lasts depends on its storage conditions. Whether in vials, pens, or cartridges, insulin actually has two expiration dates.
Until its expiration date if unopened
Each small glass bottle of insulin has its own expiration date. Most of the time, you will find it on the carton box or printed on the vial itself.
The insulin contained in the vial is good until that specific expiration date. During that time, it must be kept in the fridge. Remember that insulin is a temperature-sensitive medicine that needs to stay refrigerated.
If your vials of insulin are properly stored in your fridge, they're safe to use until they expire.
Related article: Does Insulin Really Need to Be Refrigerated?
For about a month once opened
Once opened, insulin vials only last for about a month independently of their labeled expiration date. That's because insulin is only stable at room temperature for an average of 30 days (28 days for Lantus, up to 42 days for some insulin, and even 56 days for others like Tresiba).
After that time, the medicine starts deteriorating and losing efficiency, so it may not work properly anymore. Besides, the risks of your insulin going bad increase considerably.
Here's more precise information about the exact number of days your insulin vials last once opened or out of the fridge depending on the brand of insulin you're using:
Related article: Insulin Storage: 10 Common Mistakes to Avoid When Storing Your Insulin Pens and Vials
How to store your vials of insulin?
Proper insulin storage is essential to maintain its effectiveness and avoid wasting this temperature-sensitive medication. Whether your vial is unopened or already in use, following these guidelines helps ensure your insulin stays safe and works as intended.
Before Opening (Unopened Vials):
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❄️ Refrigerate between 36°F and 46°F (2°C - 8°C) - Keep insulin in the fridge until its expiration date.
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🚫 Do not freeze - Freezing damages insulin and makes it unusable. If it has frozen, discard it immediately.
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🌞 Protect from direct sunlight and heat - Store in original packaging or a dark place inside the fridge.
After Opening (In-Use Vials):
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🌡️ Keep at room temperature (below 80°F / 26°C) - Once opened, insulin can be kept out of the fridge, but never exposed to heat.
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⏳ Use within 28 to 42 days - Most insulins are good for 28 days at room temperature, though some brands like Levemir and Tresiba last longer. Always check your specific insulin's label.
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🔁 Do not put it back in the fridge - Re-refrigerating opened insulin can cause temperature fluctuations and reduce effectiveness.
💡 Tip: When traveling, use an insulin travel cooler to maintain safe storage conditions away from home.
Related article: How to Store Insulin Without Refrigeration?
Keep your insulin vials refrigerated while traveling with 4AllFamily's medical travel coolers!
How to dispose of insulin vials?
Empty, old, or expired vials of insulin must be disposed of immediately so there's no possible confusion with the good ones. The disposal of insulin vials, pens, and cartridges may vary according to local laws.
Sometimes, it's fine to throw your vials in the household trash. They do not recycle. In that case, make sure to empty them first.
You may also be required to dispose of your insulin vials through a drug collection program or to place them in certain containers. Ask your pharmacist.
Used needles and syringes must be disposed of in sharps containers!
Related article: How to Dispose of Insulin Needles, Syringes, Pens, and Vials Safely?
How many vials of insulin do you need per month?
How many vials of insulin you need per month really depends on the treatment plan decided with your doctor. Diabetes is a disease that affects each person differently. Insulin dosage is highly variable from one person to the other.
While some diabetics are fine with 10 units of long-acting basal insulin, others need 50 units plus 60 units or more of fast-acting bolus insulin per meal! However, to give you an idea, most diabetic patients use two to three vials of insulin per month.
How to calculate the number of vials of insulin per month?
Determining your monthly insulin needs doesn't have to be complicated. Once your daily dosage is stable (as prescribed by your doctor), you can estimate how many vials you'll use each month using this simple formula.
📊 Step-by-Step Calculation:
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🔢 Know your daily insulin dose- For example: 50 units per day (this includes both basal and bolus if applicable).
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🗓️ Multiply by 30 (days in a month)- 50 units/day × 30 days = 1,500 units per month
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💉 Find out how many units are in your insulin vial- Most U-100 insulin vials contain 10 ml = 1,000 units- Smaller vials (e.g., 3 ml = 300 units, 5 ml = 500 units) are also available for some brands.
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➗ Divide your monthly insulin units by the vial size- 1,500 units ÷ 1,000 units per vial = 1.5 vials needed per month
📌 Tip: Always round up and keep an extra vial on hand to avoid running out early.
Related article: How to Calculate Your Insulin Dose Correctly?
How many units of insulin are in a vial?
Knowing how many insulin units are in a vial helps you calculate your monthly needs and avoid under- or over-ordering. The answer depends on vial size and insulin concentration.
Standard U-100 Insulin Vials
Most insulins in the U.S. come in U-100 concentration, meaning 100 units per milliliter (ml).
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🧪 10 ml vial = 1,000 units (most common)
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🧪 5 ml vial = 500 units (e.g., Lantus)
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🧪 3 ml vial = 300 units (e.g., Humalog, Humulin N, Humulin R)
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🧪 15 ml vial = 1,500 units (rare, but available)
📌 To calculate: Multiply the number of ml by 100 (for U-100 insulins).Example: 5 ml × 100 = 500 units
Other Insulin Concentrations
Some insulins come in different concentrations. Always check the label!
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💧 U-40 = 40 units per ml
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💧 U-200 = 200 units per ml
Example Calculations:
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10 ml of U-40 = 10 × 40 = 400 units
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10 ml of U-200 = 10 × 200 = 2,000 units
Special Cases & Exceptions
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🇺🇸 In the U.S.:
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🐕 U-40 insulin is only used for pets
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🖊️ Humalog U-200 (insulin lispro) is the only insulin for humans not sold as U-100, but it's only available in KwikPens, not vials - so no confusion.
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How much does a vial of insulin cost?
In the United States, the price of a vial of insulin is around $200 without health insurance According to a 2018 report, you can find over-the-counter insulins sold at Walmart for as little as $25 per vial, while the newest insulins cost between $175 and $300 per vial.
Using human insulin sold at Walmart may have serious consequences on your blood sugar levels and diabetes management. These insulins do not work the same way as analog insulins do. They may have different times of action, peak times, as well as reduced effectiveness. Always ask for your doctor's advice before using a different brand of insulin than the one you've been prescribed.
Related article: What happens if you miss a dose of insulin?
Insulin is a very expensive medicine. Keep your vials safe, and protect them from shattering and bacterial contamination. Use a silicon insulin vial protector like the ones from 4AllFamily. These little things can make you save hundreds of dollars worth of medicine!
Check 4AllFamily's insulin vial protectors here!
📌 Key Takeaways:
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📆 Unopened insulin vials last until their expiration date if stored in the fridge (36°F-46°F / 2°C-8°C).
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⏳ Opened insulin vials are effective for 28-42 days at room temperature (below 80°F / 26°C), depending on the brand.
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💉 Most insulin vials contain 1,000 units (10 ml of U-100 insulin), but sizes and concentrations can vary.
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🧮 Monthly insulin needs depend on your prescribed dose-most people use 2-3 vials per month.
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💰 Vial prices range from $25 (Walmart over-the-counter) to $300, making proper storage and handling essential.
💬 We'd Love to Hear From You!
Managing insulin can feel overwhelming-but you're not alone. Do you have tips for storing insulin, questions about dosage, or experiences with different vial types? Share your thoughts in the comments below! Your insight could help someone else on their diabetes journey.
📆 Article Update History:
✅ Updated: March 24, 2025
Originally Published: August 09, 2022
