Hey all, I’m a bit confused by the refrigeration requirements for Lantus. I understand that at room temperature it lasts for 28 days and that once it becomes room temperature, I start to count 28 days from that moment and toss it, but how long can it actually be out of the fridge? Just enough time to pull a shot and then put it back in? Does keeping it in a well-cooled cooler count as refrigeration? If I let it sit out for too long and then put it back in the fridge does that prolong its life? I’m sure like everything with this disease it isn’t rocket science but I’m lost!

hi @lucyinthesky827 Lucy, no worries, the makers of Lantus are saying 2 things at the same time, and there’s multiple reasons for it.

The thing is that most people only refrigerate their “stock” pens and vials. When the pen or vial is new (unopened, you’ve never pushed a needle through it) , it can stay in the fridge until the expiration date. The reason is that Lantus will break down over time, when exposed to heat and sunlight. If your fridge breaks and it takes a week to replace it and you’ve protected your Lantus in a cooler or just kept it below 80F/27C, and out of the sunlight, yes you will be okay putting it back in the new fridge.

Many people just keep the pen that they are using in a kit when they are out and about and that’s okay as long as you don’t cook it in a car or leave it exposed to sunlight. Used this way, you have 28 days. No you can’t get more life if you keep it in the fridge one you’ve started to use it.

Once you “open” your Lantus, Once you pierce the pen with a needle or pierce the vial, you’ve now introduced contamination. Once you’ve begun to use the Lantus, they recommend 28 days, based on microbial growth in the pen or vial. The instructions include “28 days regardless of refrigeration” meaning it’s not recommended to use a vial that’s been used after 28 days even if it is in the refrigerator. The scary part about contamination is that cells can grow quickly…exponentially actually.

All manufacturers use thermal stability and microbial growth models to estimate that there are no expected “failures” in a sample size of about 1 million. This means that most likely, you’ll be fine at day 30, day 40 and with a little luck at day 50 after you’ve opened the vial.

hope I haven’t made things worse.


Lol, you haven’t made things worse. I’m just confused about my kid’s prescription now because he was only given 5 refills of Lantus in a year? Which tells me we should be figuring out how to keep those suckers going for more than 2 months…

@lucyinthesky827 Hi Lucy, it’s common for the Rx to say 5 refills and put an end date of 1 year. Mine say 5 refills. When I get to the last one I renew the refill by having the pharmacy contact the doctor, or I contact the doctor and have them send a new script, and so on, for a very long time now.

This allows the doctor to be in control… “I won’t renew your script unless you come in and I can charge you for a visit” type mentality… Think of it as an economy.

Your child needs what your child needs. you don’t want to ration insulin or test strips or whatever, you work with the doctor. example… I use ~53 units per day, I have my doctor put “USE 70 UNITS PER DAY” on the script meaning my single month script is 2 vials, but my 3 months script is for 7 vials. Now even though that written instruction says 70, I sure as heck don’t use 70, I use what I need and I ensure I have enough for the period covered… and because I only pay 1 copay per script/3 months… to have a little extra.

so with 6 vials in the fridge… I keep the one I am using in “ambient” and it’s gone in about 20+ days.

are you sure I am not making it worse? =)


Hi Lucy @lucyinthesky827, I agree fully with what @Joe wrote, but I also want to add a reason why the insulin pen or vial your son is actively using should not be refrigerated.

“Cold insulin” is more apt to form lumps at the injection site and is also somewhat slower being absorbed and doing what it should be doing. In the long-term his tissue ability to absorb insulin could be compromised; I had always used COLD insulin during my first 40 or so years before I learned that room-temperature insulin is more effective in my body.

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@joe @Dennis You guys are THE BEST. Thank you so much for your help!

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I fully agree with what has been said. I use at least 20 units of Novalog a day and 22 units of Lantus a day. I keep my supply in my refrigerator. My Novalog pen is done in 5 days, the Lantus is about the same. I take a pen from the frig as I need it. If on travel I will removed the amount of pens I would normally need, and double the number, and once at destination put the unused pens in the refrigerator.

Well, sort of. WHat I’ve been doing for many years now (for my insulin pump) is to pull a vial out of the fridge, fill the cartridge (ka syringe) brace it upright in the appropriate direction overnight, and put the insulin vial back in the fridge. The cold insulin causes more tissue damage, but the other feature is entrained air bubbles.
When cold any small air bubbles in the insulin will be somewhat smaller, and the insulin is “stiffer”. What can happen, particularly in a pump cartridge, is that if put into the pump cold the hidden air bubbles will remain in some number even after tapping it to clear out the bubbles. Eventually as time goes by the insulin warms up the hidden bubbles expand and my combine. When an air bubble gets into the infusion hose ir displaces some insulin that you THOUGHT you had absorbed, and you bg goes up accordingly. Makes balancing your diet incredibly difficult.
Also, as I’ve always understood the 28 day room temp limit, it was set many years ago when tests were run to prove what’s good. At the end of 28 days at a CONSTANT 87F it was determined that the insulin had lost 1% of it’s strength, and that was set as the standard. So yes, you could keep using it, but only need to add 1% to the dose to be equal to normal, but at our dosages that isn’t likely a real factor.
Have never seen anything about microbial growth in insulin, since ALL insulins have had a cresol additive put in the vial which kills all microbes that may get in there. BTW cresol is related to the dark material that phone poles are coated with to avoid being invaded by bugs or microbes that would destroy them too soon. Have you seen any phone poles that started falling over after 28 days (or even 28 years)??
I’ve learned a few things in my 63 years experience with Type 1.

The main thing is contamination and effectiveness wearing off due to heat and age. Don’t reuse needles and your fine.

Keep the insulin under 80 out of sunlight and watch your numbers. Manufacturers have said insulin degrades about 0.1% in 28 days in the fridge and up to 1% at 77 degrees and no sunlight.

Add that to the fact that manufacturers can range between 90 and 100% strength per batch. Transport and storage isn’t regulated and has been seen to not be consistently cool.

We use the same vial until it runs out or it shows to be less effective (Lantus and Humalog). We went almost 6 months on Humalog and are on 7 with Lantus with no issues. Some people store it in a pantry and not the fridge for a year or so.

All that to say, your experience will change vial to vial.