My Fridge Lost Power. Are My Peptides Still Good?

The short version

Most likely yes, but you are probably asking about the wrong number.

How long the power was off matters less than how warm the contents got. A fridge with the door shut stays cold for about four hours after the power stops.¹ So a twelve-hour outage is not twelve hours of warm storage.

A fridge that comes back reading 51°F has not left the range these labels already cover. Most of them allow weeks above that, and the table below gives each one.²³⁴⁵

One thing does flip the answer to no, with no allowance at all: freezing.

Why is a twelve-hour outage not twelve hours of warm storage?

A closed refrigerator does not warm up the moment the power stops. The federal food safety guidance puts it at "about 4 hours if the door is kept closed," with a full freezer holding for "about 48 hours, or 24 hours if it is half-full, if you don't open the door."¹

That guidance is written about food, and its thresholds are about bacterial growth in chicken, not peptide chemistry. Physics does not care which, and an insulated box full of cold things takes hours to warm up to the temperature of the room.

So the figure that decides this is the temperature the contents reached and how long they held it, not the length of the outage. That makes a thermometer already sitting inside the fridge the most valuable object in the house, because a reading of 51°F is an answer and "the power was off overnight" is a guess. In practice it is a guess that overstates the exposure, since the fridge spent the first stretch of that outage still cold.

The four-hour figure assumes a shut door and a reasonably full fridge. Opening the door to check spends that reserve, and checking is the first thing most people do. Emptier fridges also coast for less time, since there is less cold mass inside to warm up.

What do the labels actually allow?

Every one of these products carries a written allowance for time out of the refrigerator. Those numbers are not the same from one product to the next, and they are not the same from one presentation of the same product to the next. A temperature excursion, meaning any period when a product sat outside the storage range printed on its label, is assessed against that product's own allowance and nobody else's. So there is no class-wide number for GLP-1 medicines, and no molecule-wide number either.

Product and presentation	Refrigerated storage	Allowed out of the refrigerator
Wegovy single-dose pen	36°F to 46°F (2°C to 8°C), in the original carton until administration	"If needed, prior to cap removal, the pen can be kept from 8°C to 30°C (46°F to 86°F) up to 28 days"²
Wegovy tablets	Not a refrigerated product. 68°F to 77°F (20°C to 25°C)	"excursions permitted to 15°C to 30°C (59°F to 86°F)"²
Ozempic pen, before first use	36°F to 46°F (2°C to 8°C), in the original carton until administration	No room-temperature alternative stated³
Ozempic pen, after first use	36°F to 46°F (2°C to 8°C)	56 days at controlled room temperature³
Ozempic single-dose prefilled syringe	36°F to 46°F (2°C to 8°C)	46°F to 86°F (8°C to 30°C) up to 28 days³
Mounjaro single-dose pen or single-dose vial	36°F to 46°F (2°C to 8°C)	Not to exceed 86°F (30°C) for up to 21 days⁴
Zepbound single-dose pen or single-dose vial	36°F to 46°F (2°C to 8°C)	Not to exceed 86°F (30°C) for up to 21 days, and not to be put back in the refrigerator afterwards⁵
Zepbound or Mounjaro multi-dose vial or KwikPen, unopened	36°F to 46°F (2°C to 8°C), usable to the expiry date on the label	30 days at room temperature up to 86°F (30°C)⁴⁵

Figures as of October 12, 2026. Each is quoted from the current label or, for Wegovy, from the manufacturer's own product site. Labels are revised, so the one in your carton is the authority over this table.

Measured against that, a fridge that drifted to 51°F sits inside the 46°F to 86°F band Wegovy and the Ozempic prefilled syringe both name, and under the 86°F ceiling Mounjaro and Zepbound both set. For those four, the hours the fridge spent warm were hours the label already accounts for.

The outlier is the Ozempic pen after first use. Its label offers two conditions, refrigeration at 36°F to 46°F or 56 days at controlled room temperature.³ A fridge sitting at 51°F is neither of those. That is a genuine blank in the document, and it is the sort of thing a pharmacist is there to resolve.

Why the single-number answers are wrong

Consumer drug pages answer this with one figure, and for the presentation most people hold they get it right. A Healthline explainer gives Zepbound as storable "unrefrigerated for up to 21 days" at a room temperature that "doesn't exceed 86°F (30°C)."⁶ A Ro guide gives tirzepatide the same window, saying it "can sit at room temperature (below 86°F) for up to 21 days."⁷ Both match the label for a single-dose pen or vial.

Where they come apart from the label is scope. The Ro guide states that storage is the same "regardless of the form."⁷ It is not. The Zepbound label gives 21 days to the single-dose pen and single-dose vial, and 30 days at room temperature to an unopened multi-dose vial or KwikPen.⁵ Neither page mentions the multi-dose vial or the KwikPen at all, so a reader holding one is given a number that is nine days short of what their own carton allows.

The return-to-the-fridge instruction has the same problem in reverse. Both pages say the medicine should not go back in the refrigerator, and Ro puts it as "Don't return the medication to the refrigerator."⁷ The label does carry that instruction, and it is written specifically for the single-dose presentations: "If single-dose pen or single-dose vial is stored at room temperature, it should not be returned to the refrigerator."⁵ Applied flatly to a multi-dose vial or KwikPen, it becomes a prohibition the label does not state.

Neither page addresses a power outage, which is why the question keeps coming up unanswered. And the fallback advice when someone is unsure, in Ro's wording, is to "err on the side of caution: Don't inject it."⁷ That is defensible as a last resort and it skips the step in between, which is the one FDA actually recommends: establish what temperature was reached, check it against the storage instructions, and ask the pharmacist or manufacturer.⁸ For a reader with one pen that shortcut costs little. For a reader with a year of vials in a fridge that drifted to 51°F, it is the difference between a phone call and binning the lot.

So which matters more, the hours or the temperature?

Those two numbers do different jobs. The temperature reached decides whether you are inside the label's allowance at all. Every allowance in the table above is written as a ceiling: 86°F for the tirzepatide products, 86°F for Wegovy and the Ozempic syringe. Stay under the ceiling and the allowance applies. Go above it and the label stops covering you, and no number of hours is short enough to put you back inside a condition the document does not describe.

Duration then draws down a budget denominated in days. Twenty-one days, twenty-eight days, thirty days, fifty-six days. An overnight outage spends a fraction of one of those, which is why the two questions have to be answered in that order: the reading tells you whether the label covers you at all, and only then do the elapsed hours tell you how much of the allowance has gone.

Freezing is the exception to all of it, because it has no budget. "Do not freeze MOUNJARO. Do not use MOUNJARO if frozen."⁴ "Do not freeze ZEPBOUND. Do not use ZEPBOUND if frozen."⁵ "Do not freeze OZEMPIC and do not use OZEMPIC if it has been frozen."³ Novo's guidance for Wegovy is to "throw away the pen if Wegovy has been frozen."² None of those sentences has a duration attached, because none of them is about accumulated exposure.

In an outage the freezing risk sits in the restart more than in the hours without power. Fridges coming back on can overshoot, and a vial pushed against the back wall or sitting near the cooling element is the one that finds out. Two of these labels address that spot by name. Ozempic's tells you not to store the pen "directly adjacent to the refrigerator cooling element,"³ and Wegovy's says "do not store WEGOVY in the freezer or directly adjacent to the refrigerator cooling element."²

Does the clock start, and can it go back in the fridge?

The Zepbound label addresses returning a pen to the refrigerator directly. Its answer is restrictive. "If single-dose pen or single-dose vial is stored at room temperature, it should not be returned to the refrigerator." Alongside it: "Discard single-dose pen and single-dose vial if not used within 21 days after removing from the refrigerator."⁵

Read literally, those two sentences describe a one-way door. Take a single-dose Zepbound pen out, and it has 21 days and no route back to cold storage.

One part of this is unresolved, and it belongs with a pharmacist instead of a table. Neither sentence describes a refrigerator that warmed up with the pen still inside it. The trigger in the label is "removing from the refrigerator," and nothing was removed. The pen never left; the cold did.

The labels were not written for this case. They were written for a patient who takes a pen on holiday. Power cuts produce a state the document does not name: the product stayed where it was supposed to be, and the place it was supposed to be stopped working.

Two readings are defensible, and neither is obviously right. The conservative reading treats the warm hours as the start of the 21-day or 28-day window, and treats return to the fridge as closed off for Zepbound's single-dose presentations. The permissive reading treats a brief in-place excursion as not having triggered anything, because the pen was never removed.

Reasoning does not settle it. The manufacturer's medical information line or the pharmacy that dispensed it does, because both can see stability data that was never printed on the carton. Calling one of them is also exactly what the federal guidance tells you to do.

How do you assess a temperature excursion?

Only one of these products defines the word on its own label, and it is the one nobody stores cold. Wegovy's tablets are a room-temperature product at 68°F to 77°F with "excursions permitted to 15°C to 30°C (59°F to 86°F)."² That wording is the familiar pharmaceutical construction, giving a target range, a wider permitted range, and no day count at all. The refrigerated injectables are written the other way round, with a ceiling and a day budget, which is why assessing one of those takes more than reading a single line.

Assessing an excursion comes down to four things you can establish standing at the fridge, and one phone call.

What temperature did it reach? Any minimum and maximum thermometer answers that directly. One showing only the current temperature answers it partially, since the fridge has been recovering since the power came back. With no thermometer at all you are estimating, and the estimate should be generous about how warm it got.

With no thermometer there is still a hard ceiling to reason from. Refrigerators cannot get warmer than the room they stand in, so the room temperature during the outage is the worst case for the contents. If the house held 72°F, the fridge cannot have gone above 72°F, which is below every ceiling in the table above. That reasoning fails in two places, both covered further down: a fridge in a garage or an outbuilding, and a house that lost air conditioning in a heatwave.

Did it freeze at any point? Look for ice where ice should not be, and look at the liquid in the cartridge or vial for anything that was not there before. A yes here ends the assessment.

How long was it above the labelled ceiling? That is not the same as how long the power was off, and the four-hour coasting figure is why.¹ The two numbers usually differ by several hours.

What does this specific product's label allow? The table above gives it, and the carton in your hand outranks the table.

Then the call. FDA's current guidance, on a page carrying a content date of September 1, 2026, says that if a medicine has not been kept at the recommended temperature during a power outage you should "check the medicine's storage instructions, if available" and "contact a pharmacist, health care provider, or the manufacturer."⁸ The same page notes that "temperature-sensitive medicines may lose potency when they are not stored at the recommended temperature" and that you should "replace medicines that can no longer be used with a new supply as soon as possible."⁸

That is a two-step instruction, and most people do only the second half of it. Looking up the number first changes the conversation. "My power went out" becomes "my fridge reached 51°F for roughly eight hours and my label allows 28 days up to 86°F," and that second version is a question a pharmacist can answer in a sentence.

How does this compare with insulin?

Insulin is the refrigerated injectable with the longest public record on this exact question. FDA maintains a page on it.

Vials and cartridges as supplied by the manufacturer, "opened or unopened," "may be left unrefrigerated at a temperature between 59°F and 86°F for up to 28 days and continue to work."⁹ One newer once-weekly insulin has a longer window still: "Once removed from the refrigerator, or when in use, Awiqli pens may be stored at room temperature below 86°F for up to 12 weeks," with the total combined room-temperature time capped at 12 weeks.⁹

So the scale of these allowances is weeks to months, not hours. Overnight outages belong in that context.

That same page is blunt about what heat does over time. "Extreme temperatures make insulin less effective." "The longer insulin is exposed to extreme heat or cold, the less effective it becomes."⁹ It is also blunt about what to do once the emergency is over: "Once you have access to properly stored insulin, throw away any vials that were exposed to extreme temperatures and replace them as soon as possible."⁹ That last instruction is the one that resolves the apparent contradiction in emergency guidance. Keep using it if you must, and stop using it as soon as you do not have to.

What is different about a compounded vial?

A compounded preparation has no FDA-reviewed stability data behind it. FDA states plainly that for these products "the agency does not review compounded versions of these drugs for safety, effectiveness, or quality," and that compounded drugs are "not FDA-approved or evaluated for safety and effectiveness."¹⁰ That does not make a compounded vial inherently more fragile than an approved one. What it lacks is a section 16 to look up, because no regulator reviewed a stability programme that would generate a published excursion allowance.

What exists instead is a beyond-use date, meaning the date the compounding pharmacy assigned to that specific preparation based on its own formulation and standards. That date is the pharmacy's, so the pharmacy is the only party who can tell you what a temperature excursion does to it.

Establishing who filled it also helps. FDA's advice is to "only obtain medicines from state-licensed pharmacies or outsourcing facilities registered with FDA,"¹⁰ and those are two different kinds of operation: the state-licensed pharmacy, known in the regulations as the 503A route, and the FDA-registered outsourcing facility, the 503B route. Neither issues a document with a section 16 in it, so either way the answer comes from whoever made the preparation.

A compounded vial also differs from the products in the table in ways the table cannot show:

It usually arrives already in solution. Everything on the approved-product side of this page concerns a liquid too, so the comparison holds, but none of the dry-powder reassurance further down applies to it.
The formulation may not match the approved product. FDA has noted that some compounded semaglutide has used salt forms, and that "the salt forms are different active ingredients than is used the approved drugs, which contain the base form of semaglutide."¹⁰ A different active ingredient behaves differently, and the approved label's 21 or 28 days does not transfer to it.
Nobody is obliged to tell you which one you have.

So calling the pharmacy that dispensed it is the only route to an answer here, and it goes better before an outage than during one, since the people who can answer keep office hours.

What about lyophilised research powder?

Dry powder is the one category where a fridge outage is close to irrelevant. Refrigeration was never what was protecting it.

Lyophilised means freeze-dried: the water has been removed, leaving a solid cake. Nearly every route by which a peptide degrades needs water as either the reactant or the medium, so taking the water out slows all of them by orders of magnitude. Sealed dry powder tolerates weeks to months at room temperature, which is why suppliers ship it without ice in the first place.

Our guide on peptides that arrive warm covers that chemistry in full, along with what heat in transit actually costs and why the vial that arrives cold carries a handling risk the warm one does not. One night at 51°F has done less to a sealed vial of powder than a single warm delivery would.

A vial that was already reconstituted is a solution and not a powder, so it belongs with the compounded case above. Research-labelled material carries no label at all, so there is no number to look up and no manufacturer stability programme standing behind one. The absence of a published allowance is not the same as a generous one. It means nobody has measured it.

What if it was the freezer and not the fridge?

Freezers buy considerably more time than fridges do. The federal figure is "about 48 hours, or 24 hours if it is half-full, if you don't open the door," against about four hours for a refrigerator.¹ A full freezer absorbs a day-long outage that would have spent a fridge's whole margin six times over.

What the thawing means depends on what was in there.

Sealed lyophilised powder is the case where a thawed freezer is close to a non-event. Freezing was never what protected it, so losing the freezing takes nothing away. Moisture and peak temperature are what count for dry powder, and a freezer that drifted up to fridge temperature has delivered neither.

A reconstituted vial in a freezer was in the wrong place before the power ever went out. Every approved label on this page prohibits freezing outright. Thawing has moved it towards its correct storage temperature, and it still carries whatever the earlier freezing already did to it.

One physical test tells you whether a freezer actually lost its cold, and it needs no thermometer. The federal food guidance treats ice crystals as the marker, saying food "can be safely re-frozen if it still contains ice crystals or is 40°F (4°C) or below."¹ Ice crystals form the same way whatever the contents, so finding them tells you the compartment stayed cold. That is an observation about temperature and nothing more. It is not permission to refreeze a medicine, and no label on this page supports refreezing anything.

What about a whole stockpile?

Every vial in the same fridge went through the same excursion, so a stockpile is one assessment and not forty. One temperature reading covers the lot. That same arithmetic means one bad reading implicates the lot, which is why the reading deserves a thermometer instead of an estimate.

Full fridges also coast for longer than empty ones. That four-hour figure assumes a reasonably stocked compartment, and a few dozen cartons are cold mass doing the same job that a freezer full of food does. So the person with the deepest stockpile had, other things being equal, the slowest temperature rise in the house.

What works against a stockpile is time, not this one outage. A label's day allowance is cumulative, and a vial bought to be used in eight months has eight more months of outages, house moves, holidays and warm car journeys ahead of it before anyone injects it. It only runs down, never back up. A vial being used next week has almost no exposure left to accumulate, while a vial at the back of a year's supply has all of it.

So writing down the date and the peak temperature beats carrying them in your head. Cumulative accounting across a year is not something anyone does from memory, and the stockpile holder is the one person it really applies to.

When is the answer actually no?

Freezing is the single condition every one of these labels treats as disqualifying. No tolerance period attaches to it at all, so it sits apart from everything else on this page.

Other situations fall outside the reassurance on this page:

The thermometer read above 86°F. An outage in summer with no air conditioning can do this, particularly if the fridge door was propped open or the unit lives in a garage. Above the ceiling the label's allowance no longer describes your situation.
The exposure was long rather than overnight. A five-day outage is not a twelve-hour outage with a bigger number. Several days at ambient temperature spends a real fraction of a 21-day or 28-day budget and may exceed it.
The excursions have stacked. A label's allowance is cumulative, not per-incident. Mounjaro's instruction for a multi-dose vial is to throw it away "after a total of 30 days at room temperature,"⁴ and Awiqli's cap is on "the total combined time at room temperature."⁹ An outage in July and another in October draw on the same budget.
The product is one you cannot verify. A vial with no label, no lot number and no manufacturer to call has no assessable excursion at all, because there is no baseline to assess it against.

What if you cannot replace it?

FDA addresses the case where the medicine is needed and no replacement is available. Its guidance has been consistent across a decade of its own pages.

The 2016 version: "If electrical power has been off for a long time, refrigerated drugs should be discarded. However, if the drug is absolutely necessary to sustain life (insulin, for example), it may be used until a new supply is available."¹¹

The current version, dated September 1, 2026: "If the medicine is needed to sustain life (for example, insulin)," then "it may be used until you can get a new supply."⁸

Both of those are narrower than they first appear. The permission is for a medicine needed to sustain life, and it is explicitly temporary. The insulin page closes the loop by saying to discard and replace once properly stored supply is available.⁹ Most weight-management prescriptions are not in the sustain-life category, which cuts both ways. Missing a week is not a medical emergency, so the case for using a questionable vial is weaker. Discarding one costs money and nothing else, and for a stockpiled supply that is not a small thing. Getting an actual temperature reading matters most in exactly that case, before anyone throws anything away.

What should you do before the next outage?

A thermometer turns this whole question from a guess into a reading. Get a minimum and maximum model, meaning one that records the extremes it saw instead of only the current temperature, because the extreme is the number you will want. They are inexpensive, and they go inside the fridge rather than on the door.

The rest is quick:

Keep the door shut when it happens. The four-hour figure assumes a closed door, and checking on things is what spends the reserve.¹
Know your own number before you need it. It is one line in section 16 of your label, or one question to a pharmacist, and it converts a night of worry into arithmetic.
Have ice available. FDA's older guidance gives exactly one piece of concrete preparation, and this is it: "Have ice available for medications that need refrigeration."¹¹

A cooler with ice packs and a thermometer in it beats a dead fridge, with one caution. The goal is cool, not cold, and direct contact with ice risks the one failure mode that has no tolerance at all. FDA's insulin page makes the same point about emergency cooling, saying that "if you are using ice, avoid freezing the insulin."⁹

What this page cannot tell you

The numbers above are storage allowances, not stability guarantees for a specific vial. Those 21 days reflect what the manufacturer demonstrated and chose to commit to, and a vial that spent 22 days at 85°F has not therefore failed. It has left the range anyone will vouch for.

Potency loss is usually invisible. No appearance change reliably marks a solution that has lost strength, so the assessment runs on temperature records instead of on inspection. Visible change is useful evidence when you find it. Finding none is not evidence of anything.

A pharmacist or manufacturer can be more permissive than a label, and this page cannot be. They can see stability data that was never printed on a carton. That is why the federal guidance points you at them instead of at a table.

None of this is dosing advice, and none of it is a reason to change what you take or when. It is about whether the product in your hand is still what the label says it is.

Common questions

My power was out for 12 hours and the fridge read 51°F. Is my medication ruined?

Almost certainly not. A closed fridge holds temperature for roughly four hours, so the warm period was shorter than the outage itself. That 51°F reading also sits inside the room-temperature range Wegovy and the Ozempic prefilled syringe both permit for up to 28 days, and under the 86°F ceiling Mounjaro and Zepbound set for 21 days. Confirm against your own carton and call the pharmacy if you want it documented.

Which matters more, how long the power was off or how warm it got?

How warm it got decides whether the label's allowance covers you at all, because every allowance is written as a temperature ceiling. How long it lasted then spends a budget measured in days. Temperature is the gate; time is the meter.

How long can Mounjaro be out of the fridge?

The label gives a single-dose pen or single-dose vial up to 21 days unrefrigerated at temperatures not exceeding 86°F (30°C). An unopened multi-dose vial gets 30 days at room temperature up to 86°F, and can otherwise be used to the expiry date if kept refrigerated. Do not use it if it has been frozen.

How long can Zepbound be unrefrigerated?

The same 21 days at temperatures not exceeding 86°F (30°C) for a single-dose pen or single-dose vial, and 30 days at room temperature for an unopened multi-dose vial or KwikPen. One extra instruction applies to Zepbound's single-dose presentations: once stored at room temperature, the label says they should not be returned to the refrigerator.

How long can Wegovy be out of the fridge?

Up to 28 days, from 46°F to 86°F (8°C to 30°C), kept in the original carton and before the pen cap is removed. Do not freeze it, and throw the pen away if it has been frozen.

How long can Ozempic be out of the fridge?

This one depends on the presentation and on whether you have started it. Before first use the pen has no room-temperature alternative stated at all; it stays refrigerated at 36°F to 46°F in its carton. After first use the pen can be kept for 56 days at controlled room temperature or back in the fridge. A single-dose prefilled syringe can be kept from 46°F to 86°F for up to 28 days.

I take the Wegovy tablets, not the injection. Does any of this apply?

Not really, because the tablets were never a refrigerated product. The label stores them at 68°F to 77°F (20°C to 25°C) with "excursions permitted to 15°C to 30°C (59°F to 86°F)," so a fridge losing power is not an event for them. Keep them in the original bottle and away from moisture, which is what that label asks for.

How long does a refrigerator stay cold without power?

About four hours with the door kept closed, per federal food safety guidance. A full freezer holds about 48 hours, or about 24 hours if it is half-full. Opening the door is what shortens both figures.

Can I put it back in the fridge once the power comes back?

For a Zepbound single-dose pen or vial, the label says that if it has been stored at room temperature it "should not be returned to the refrigerator." Whether a fridge that warmed up in place counts as having removed it is not addressed by the label, and that is a question for the manufacturer's medical information line or your pharmacist.

Does the 21-day or 28-day clock start over after an outage?

The labels do not say, because they describe a product being taken out of a refrigerator and not a refrigerator that stopped working. Treat the allowance as cumulative, since the labels that quantify it do: Mounjaro's multi-dose vial instruction is to discard "after a total of 30 days at room temperature."

What if it froze?

Freezing is where the answer is simply no. Every label here says not to use the product if it has been frozen, with no tolerance period attached. Freezing is more likely on restart than during the outage, so check for ice and look at the liquid before using anything.

Is a 51°F fridge actually a problem for anything?

It is above the 36°F to 46°F refrigerated range every one of these labels specifies, so it is technically an excursion. It is also below the 86°F ceiling most of them permit for weeks. For most products in the table, it was inside an allowance that already existed.

My medication is compounded, not a brand pen. Does any of this apply?

Not the numbers. FDA does not review compounded versions "for safety, effectiveness, or quality," so there is no published excursion allowance for one. The compounding pharmacy set its beyond-use date and is the only party able to tell you what the outage did to it.

Does lyophilised powder need the fridge at all during an outage?

Refrigeration is not what protects dry powder; dryness is. Sealed lyophilised peptide tolerates weeks to months at room temperature, so an overnight fridge failure is near the bottom of the list of things that would affect it. A vial that has already been reconstituted is a different case entirely.

My freezer lost power, not my fridge. Does that change anything?

It buys you much more time. A full freezer holds its temperature for about 48 hours against a fridge's four, or about 24 hours if it is half-full. For sealed lyophilised powder a thawed freezer is close to a non-event, because dryness and not coldness was what protected it. For anything already reconstituted, the freezer was the wrong place before the outage started, since every approved label here prohibits freezing.

I had no thermometer in the fridge. Can I still work it out?

Up to a point, and the useful fact is that a fridge cannot get warmer than the room it sits in. If the house stayed around 72°F through the outage, the contents cannot have gone above that, which is well under the 86°F ceiling these labels set. The exceptions are a fridge in a garage or an outbuilding and a house that lost air conditioning in a heatwave, where the room itself can exceed the ceiling.

I have a year of vials stockpiled. Do I have to throw them all out?

Not on the basis of one overnight outage, if the temperature stayed under the labelled ceiling and nothing froze. The relevant risk with a large stockpile is cumulative, since a warm period draws down the same budget for every vial in the fridge. Record the date and the peak temperature so the next incident can be added to it rather than guessed at.

What should I tell the pharmacist when I call?

The peak temperature if you have it, how long the product was above its labelled range, whether it froze, the product and presentation, and the lot number. That turns the call into a question with an answer instead of a description of an outage.

Is there a single number of hours after which refrigerated medication is unsafe?

No, and anyone offering one is not reading from a label. The allowances differ by product and by presentation of the same product: 21 days for a single-dose tirzepatide pen, 28 days for a Wegovy pen, 30 days for an unopened multi-dose vial, 56 days for an Ozempic pen already in use.

What about a five-day outage, like after a hurricane?

That is a different problem from an overnight one, because several days at ambient temperature spends a real portion of a 21-day or 28-day allowance and the ceiling is much harder to stay under without power. A cooler with ice and a thermometer is the practical answer, keeping the product cool without letting it touch ice. FDA's guidance for a medicine needed to sustain life is that it may be used until a new supply is available, then replaced.

Can I just look at it to tell if it is still good?

Looking will catch some problems and miss the main one. Potency loss leaves no reliable visual signature, so inspection can confirm a problem and cannot rule one out. Act on ice crystals or an unexpected change in the liquid. A normal appearance is not evidence that nothing happened.

Why do two products with the same active ingredient have different allowances?

Because the allowance is a property of the finished product and its container, not of the molecule. Mounjaro and Zepbound are both tirzepatide, and within each of them the single-dose presentations get 21 days while an unopened multi-dose vial gets 30. The formulation, the container and the stability programme behind it are what set the number.

Sources

Three Ways to Keep Food Safe When You Lose Power, FoodSafety.gov. Published October 8, 2020, last modified September 21, 2023. Read at source. US federal interagency food safety guidance. States that a refrigerator will keep food cold for about 4 hours if the door is kept closed, and that a full freezer holds its temperature for about 48 hours or 24 hours if half-full if the door is not opened. Written about food safety, cited here only for the thermal behaviour of a closed appliance.
WEGOVY (semaglutide) prescribing information, section 16, How Supplied/Storage and Handling. Label text read via medlibrary.org's reproduction of the FDA label, a third-party host rather than Novo Nordisk or FDA. Quotes the pen as stored "in the refrigerator from 2°C to 8°C (36°F to 46°F)" and that "if needed, prior to cap removal, the pen can be kept from 8°C to 30°C (46°F to 86°F) up to 28 days." Also: "Do not store WEGOVY in the freezer or directly adjacent to the refrigerator cooling element." "Do not freeze WEGOVY and do not use if it has been frozen." "Protect WEGOVY from light." "WEGOVY must be kept in the original carton until time of administration." "Discard the WEGOVY pen after use." For the tablets: "Store at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F)", with a bracketed cross-reference that was truncated in the retrieved text, plus "Store and dispense WEGOVY tablets in the original bottle" and "Store WEGOVY tablets in a dry place away from moisture." No revision date appears on the reproduction. Sourcing note, two tiers. Section 16 could not be retrieved from Novo Nordisk's own label PDF or from FDA's SPL document service, both of which truncated before reaching it. Every injection figure above was independently confirmed against Novo Nordisk's own patient-facing product page, How to Use the Wegovy Pen, read at source, which gives the same refrigerated range, the same 46°F to 86°F band, the same 28 days, the same carton and light instructions and the same instruction to throw the pen away if frozen. The two routes agree on every figure. FDA's SPL record puts the current label at version 19, effective June 18, 2026, and titles it "WEGOVY (semaglutide), injection for subcutaneous use and tablets for oral use.
OZEMPIC (semaglutide) injection prescribing information, section 16, How Supplied/Storage and Handling. Revised 05/2026. Read at source. States that prior to first use the pen is stored in a refrigerator between 2°C and 8°C (36°F to 46°F), not in the freezer or directly adjacent to the refrigerator cooling element, and kept in the original carton until time of administration. After first use the pen can be stored for 56 days at controlled room temperature or in a refrigerator 2°C to 8°C. The single-dose prefilled syringe is stored refrigerated at 2°C to 8°C and, if needed, can be kept from 8°C to 30°C (46°F to 86°F) up to 28 days. Do not freeze and do not use if it has been frozen. Protect from light.
MOUNJARO (tirzepatide) injection prescribing information, section 16, How Supplied/Storage and Handling. Read at source. States that the single-dose pen and single-dose vial are stored in a refrigerator at 2°C to 8°C (36°F to 46°F) and that if needed each can be stored unrefrigerated at temperatures not to exceed 30°C (86°F) for up to 21 days. Do not freeze; do not use if frozen. An unopened vial can be used until the expiration date on the label if kept in the refrigerator, and if stored at room temperature up to 30°C (86°F) the unopened vial is thrown away after 30 days. An opened vial is thrown away after a total of 30 days at room temperature, 30 days after first use, or after taking 4 weekly doses, even if medication is left in it. Corroborated for the single-dose pen by Lilly medical information: recommended storage for the Mounjaro single-dose pen, date of last review January 14, 2026, which gives the same refrigerated range, the same 21-day unrefrigerated allowance and the same freezing prohibition.
ZEPBOUND (tirzepatide) injection prescribing information, section 16.2, Storage and Handling. Revised 02/2026, hosted by FDA. Read at source. States: "Store ZEPBOUND single-dose pen and single-dose vial in a refrigerator at 2°C to 8°C (36°F to 46°F)." "If needed, each single-dose pen or single-dose vial can be stored unrefrigerated at temperatures not to exceed 30°C (86°F) for up to 21 days." "If single-dose pen or single-dose vial is stored at room temperature, it should not be returned to the refrigerator." "Discard single-dose pen and single-dose vial if not used within 21 days after removing from the refrigerator." "Do not freeze ZEPBOUND." "Do not use ZEPBOUND if frozen." "Protect ZEPBOUND from heat and light." "Store ZEPBOUND in the original carton to protect from light." For the multi-dose vial and single-patient-use KwikPen: refrigerated storage at 2°C to 8°C, usable until the expiration date if kept refrigerated, and thrown away after 30 days if stored at room temperature up to 30°C (86°F). The sentence beginning "Throw away opened multi-dose vial or single-patient-use KwikPen after a total of 30 days at room temperature" is truncated in the retrievable PDF text; the equivalent instruction is quoted in full from the Mounjaro label at reference 4. Corroborated for the single-dose vial by the Zepbound single-dose vial Instructions for Use, read at source, which states storage at 36°F to 46°F, room-temperature storage up to 86°F for up to a total of 21 days, discarding after a total of 21 days at room temperature, not freezing, storage in the original carton, and throwing away all opened vials after use.
How long can Zepbound be unrefrigerated?, Healthline. Read at source. Secondary consumer health page, cited as evidence of what these pages tell readers and not as a source on storage. States that the pens and vials can be stored "unrefrigerated for up to 21 days" and that "the drug should remain at a room temperature that doesn't exceed 86°F (30°C)." Covers the single-dose pen and vial together. Does not mention the multi-dose vial or the KwikPen. On returning it to the refrigerator: "No, you should not refrigerate Zepbound again after taking it out of the fridge," and "it's important that you do not return it to the refrigerator."
Does tirzepatide need to be refrigerated?, Ro. Read at source. Secondary consumer health page, cited on the same basis as reference 6. States that tirzepatide "can sit at room temperature (below 86°F) for up to 21 days" and that "if you store Mounjaro or Zepbound at room temperature, it should be used within 21 days or discarded." States that storage is the same "regardless of the form," and limits its scope to "the Food and Drug Administration (FDA)-approved, brand-name versions of tirzepatide." Does not mention the multi-dose vial, compounded product, or power outages. On returning it: "Don't return the medication to the refrigerator." Advises that where someone is unsure how long it was out or whether it got too warm, to "err on the side of caution: Don't inject it."
Safe Drug Use After a Natural Disaster, US Food and Drug Administration. Content current as of September 1, 2026. Read at source. States that if a medicine has not been kept at the recommended temperature during a power outage you should check the medicine's storage instructions, if available, and contact a pharmacist, health care provider, or the manufacturer. Also states that temperature-sensitive medicines may lose potency when not stored at the recommended temperature, that medicines needed to sustain life may be used until a new supply can be obtained, and that medicines which can no longer be used should be replaced as soon as possible. Medicines that have contacted floodwater should be discarded.
Information Regarding Insulin Storage and Switching Between Products in an Emergency, US Food and Drug Administration. Content current as of September 28, 2026. Read at source. States that insulin products in manufacturer-supplied vials or cartridges, opened or unopened, may be left unrefrigerated at a temperature between 59°F and 86°F for up to 28 days and continue to work; that extreme temperatures make insulin less effective and the longer the exposure the less effective it becomes; that insulin which has been frozen should not be used and that ice should not be allowed to freeze it; and that once properly stored insulin is available, vials exposed to extreme temperatures should be thrown away and replaced. For Awiqli, once removed from the refrigerator or when in use, pens may be stored at room temperature below 86°F for up to 12 weeks, with total combined room-temperature time not exceeding 12 weeks.
Medications Containing Semaglutide Marketed for Type 2 Diabetes or Weight Loss, US Food and Drug Administration. Read at source. States that the agency does not review compounded versions of these drugs for safety, effectiveness, or quality, and that compounded drugs are not FDA-approved or evaluated for safety and effectiveness. States that salt forms are different active ingredients than is used in the approved drugs, which contain the base form of semaglutide, that FDA is not aware of any basis for compounding using the salt forms, and that products using them may not contain the same active ingredient as FDA-approved semaglutide products and have not been shown to be safe and effective. Advises obtaining prescription drugs only from state-licensed pharmacies located in the US or outsourcing facilities registered with FDA. No "content current as of" date was present in the retrievable page text.
Emergency Preparedness: Keeping Medications Safe, US Food and Drug Administration, Drug Info Rounds. Content current as of March 8, 2016. Read at source. States that ice should be available for medications that need refrigeration, that if electrical power has been off for a long time refrigerated drugs should be discarded, and that if a drug is absolutely necessary to sustain life, insulin for example, it may be used until a new supply is available. Cited here as the earlier version of the same federal guidance, to show the position has been stable.

Citing this page. Peptide Decoding. My Fridge Lost Power. Are My Peptides Still Good? Label storage and excursion allowances as of October 12, 2026. https://peptidedecoding.com/guides/fridge-lost-power