Yes. Zepbound is stored at 36°F to 46°F, but single-dose pens and vials may sit out at up to 86°F for a total of 21 days, KwikPens and multi-dose vials for 30.
Which number is yours depends on the device in your hand. This page settles the fridge rule for all four presentations, the day limit for each, when your clock started, and what to do after a porch delivery, a freeze, a power cut or a flight.
This article is general information from public sources, not medical advice. Your prescriber and pharmacist know your history; take storage and dosing questions to them.
Last updated September 2026 · Sources verified against the FDA label, the KwikPen Instructions for Use and Zepbound.com (Lilly).
Key takeaways
- All four Zepbound presentations live in the refrigerator at 36°F to 46°F, in the original carton, and never frozen. Frozen means throw it away, even after it thaws.
- A single-dose pen or vial can be out of the fridge at up to 86°F for a total of 21 days, then it is discarded, and a pen kept at room temperature does not go back in.
- An unopened KwikPen or multi-dose vial keeps to its expiration date in the fridge, or 30 days at room temperature. In use, it is discarded at the first of 30 days after first use, 30 days at room temperature, or 4 weekly doses.
Does Zepbound need to be refrigerated?
Yes. All four Zepbound presentations are stored in a refrigerator at 2°C to 8°C (36°F to 46°F), in the original carton. The FDA label, section 16, says to "Store ZEPBOUND single-dose pen and single-dose vial in a refrigerator at 2°C to 8°C (36°F to 46°F)", and the same range for an unopened multi-dose vial or single-patient-use KwikPen. That is the label as of September 2026, revision ZEP-0016-USPI-20260828.
The carton has a job too: "Protect ZEPBOUND from heat and light. Store ZEPBOUND in the original carton to protect from light."
GoodRx's pharmacists advise putting the carton in the middle of the fridge, with nothing touching it or stacked on top, and away from the door and the produce or meat drawers, which have less airflow and more temperature swing.
The label is blunt about the other direction: "Do not freeze ZEPBOUND. Do not use ZEPBOUND if frozen." A pen that freezes is thrown away even after it thaws, so the cold spot at the back is the expensive place to put the box.
Storage rules for your exact device
The fridge rule is the same for all four devices, and the day limit is not. A single-dose pen is the one-shot autoinjector with the needle attached, a single-dose vial is one dose you draw with a syringe, and a multi-dose vial or KwikPen holds four weekly doses.
Your device | In the refrigerator | Out of the fridge, up to 86°F | Throw it away when |
|---|---|---|---|
Single-dose pen | 36°F to 46°F, in the carton | Total of 21 days | After 21 days at room temperature |
Single-dose vial | 36°F to 46°F, in the carton | Total of 21 days, unopened | After that one dose, leftover included, or 21 days at room temperature |
KwikPen or multi-dose vial, unopened | 36°F to 46°F, to the expiration date | 30 days | After 30 days at room temperature |
KwikPen or multi-dose vial, in use | 36°F to 46°F, in the carton, or room temperature | Allowed, within the limits at right | 30 days after first use, 30 days at room temperature, or 4 weekly doses, whichever is first |
Does the Zepbound KwikPen need to be refrigerated, and can it stay out between weekly doses?
Yes, and between weekly doses an in-use KwikPen may sit in the fridge or at room temperature, per the FDA label, section 16. An unopened one keeps to the expiration date in the fridge, or 30 days out.
Once in use, it is discarded at the first of the three limits in the table, "even if there is medicine left in it." The KwikPen Instructions for Use explains the leftover: "Attempting to inject any leftover medicine could result in an incomplete dose."
Do Zepbound vials need to be refrigerated?
Yes, both kinds, and the difference is what happens after the needle goes in. The vial's Instructions for Use says to "Throw away all opened vials after use, even if there is medicine left in the vial", and Lilly's answers page gives the reason: "Tirzepatide does not contain a preservative."
How long can Zepbound stay out of the fridge?
Out of the fridge, Zepbound keeps for 21 days if it is a single-dose pen or vial, and 30 days if it is a KwikPen or multi-dose vial, in both cases only up to 86°F. The FDA label, section 16, sets that ceiling for the single-dose devices as "temperatures not to exceed 30°C (86°F)", and repeats it in brackets for the four-dose ones.
Anything hotter is outside the label, which is what turns a hot car or a summer porch into a question rather than a day count. In the fridge, an unopened KwikPen or multi-dose vial keeps to its printed expiration date, while a single-dose pen or vial counts only its time out against the 21 days.
When does the day clock start, and how do I keep track?
The clock starts the day a single-dose pen first leaves the fridge, and for a KwikPen it starts at the first injection. Zepbound.com (Lilly) says "Discard if not used within 21 days after removing from the refrigerator", and the KwikPen Instructions for Use says to "Throw away the Pen 30 days after first use." For a single-dose vial, the FDA label, section 16, counts "a total of 21 days at room temperature".
That date is worth logging where you will find it again. In MeAgain the KwikPen's first dose is a dated entry in your shot log, so the discard date is on record rather than a memory. More ideas in these Zepbound tracking tips.
I love this app! It helps me keep track of my diet, shot, and activity all in one place. I was worried about protein and fiber intake when I started GLP-1 journey and the app is helping me keep up with all of that and more. I log every day and it keeps me motivated.
Can a Zepbound pen that has been at room temperature go back in the refrigerator?
It depends on the device: the single-dose pen does not go back, and an in-use KwikPen or multi-dose vial may be kept in either place. Zepbound.com (Lilly) is direct about the single-dose pen: "If Zepbound is stored at room temperature, it should not be returned to the refrigerator." Its days out are still capped at the 21-day total.
The four-dose devices are written differently. The FDA label, section 16, stores an opened multi-dose vial or KwikPen "in the refrigerator... or at room temperature", and an unopened one may move either way within its 30 days at room temperature. Lilly Canada's KwikPen storage page adds that if the pen is inadvertently placed in the refrigerator, "the patient may continue to use the KwikPen."
Left out, overheated, or the power went out
Whether it is still usable comes down to which device you have, whether it stayed at or below 86°F, and how many of its allowed days the time used up.
- Name the device. Single-dose pen, single-dose vial, multi-dose vial or KwikPen, and for the four-dose devices, whether it is unopened or already in use. Each has its own day limit in the table above, from the FDA label, section 16.
- Check the ceiling. Time at or below 86°F counts toward that device's room-temperature allowance, and hotter than that is outside the label.
- Add the time to that device's total. A night on the counter counts toward a single-dose pen's 21-day total, and that pen does not go back in the refrigerator. An in-use KwikPen is allowed at room temperature anyway.
- Handle a power cut by the label. The CDC says "When the power is out for a day or more, throw away any medication that should be refrigerated, unless the drug's label says otherwise." The Zepbound label does say otherwise, within its day limits.
Whether a pen in an unpowered fridge counts as "stored at room temperature" is a question for Lilly or your pharmacist. Call them with how long it was out and how hot it got.
When a pen or vial has to be thrown away
Throw away any Zepbound that has been frozen, that looks cloudy, discolored or full of particles, that was dropped on a hard surface, or that is past its device's day limit. The FDA label, section 16, says "Do not use ZEPBOUND if frozen."
A frozen pen looks fine once it thaws. The pen's Instructions for Use settles it: "If the pen has been frozen, throw the pen away and use a new pen." For the KwikPen, Lilly Canada's KwikPen storage page defines frozen as at or below 0°C.
Then look at the liquid. The FDA label, section 2, says Zepbound "should appear clear and colorless to slightly yellow. Do not use ZEPBOUND if particulate matter or discoloration is seen."
A drop counts too. The pen's Instructions for Use says the pen "has glass parts" and that if you drop it on a hard surface, do not use it.
If you cannot tell whether a pen or vial is still usable, or you used one that may have been mis-stored, contact Lilly at 1-800-545-5979 or call your care team.
Travelling with Zepbound
Zepbound travels in the carry-on, in its original carton, and the ice pack must be frozen solid when it reaches the checkpoint. The TSA allows frozen items "as long as they are frozen solid when presented for screening." Partly melted, they must meet the 3-1-1 liquids requirements.
Do not use the checked bag. Lilly Canada's KwikPen page says "Do not pack the KwikPen in checked luggage" because hold areas "may be too cold or too hot for the Zepbound KwikPen." The same page says changes in altitude "do not impact the dose accuracy of the Zepbound KwikPen."
A hotel room with no fridge is fine for a week. Zepbound.com (Lilly) says that "if you're traveling and don't have access to a fridge, the pens can stay at room temperature for up to 21 days", so a week-long trip sits inside the single-dose window if the room stays at or below 86°F.
Frequently asked questions
Does Zepbound KwikPen need to be refrigerated?
Yes. Unopened, it keeps in the fridge to its expiration date, or 30 days at room temperature. In use, the FDA label discards it at the first of 30 days after first use, 30 days at room temperature, or 4 weekly doses.
Does Zepbound quick pen need to be refrigerated?
Yes. "Quick pen" is the KwikPen, and the FDA label, section 16, keeps an unopened one in the fridge to its expiration date, or 30 days at room temperature.
Does Zepbound pen need to be refrigerated?
Yes. Once a single-dose pen has been kept at room temperature, Zepbound.com (Lilly) says it should not go back in the refrigerator, and its days out are capped at 21.
Does Zepbound injection need to be refrigerated?
Yes, all four presentations, at 36°F to 46°F in the original carton, per the FDA label, section 16. The day limit out of the fridge is 21 days for the single-dose devices and 30 for the four-dose ones.
Why does Zepbound need to be refrigerated?
Refrigeration is the condition Lilly tested against, and the room-temperature windows are the limits of that testing. The FDA approval letter reports a stability study showing the product "maintains acceptable quality when stored in and out of refrigeration... for up to 21 days", and Lilly Canada's KwikPen storage page says the same of a KwikPen cycled across its 30 days in use. That is stability testing in product samples, not in people.
Does my Zepbound need to be refrigerated if I only have one dose left?
A single-dose vial's leftover is not stored at all: the vial's Instructions for Use says to "Throw away all opened vials after use, even if there is medicine left in the vial." A KwikPen or multi-dose vial may sit in the fridge or out until the first of its three limits.
What if my prescription was switched from pens to vials or a KwikPen?
The rules change with the device: the FDA label, section 2, says to "consult the Instructions for Use for the newly prescribed presentation." A single-dose pen or vial runs on 21 days out of the fridge, a KwikPen or multi-dose vial on 30.
Can Zepbound be left in a parked car in summer heat?
The label's ceiling is 86°F and a parked car is where it is most often passed. If you think a pen or vial went past it, call Lilly at 1-800-545-5979 or your pharmacist.
What if I left Zepbound out longer than the allowed number of days?
It is thrown away: the FDA label, section 16, says to "Discard single-dose pen and single-dose vial after a total of 21 days at room temperature." If the count is unclear, the Instructions for Use sends you to Lilly at 1-800-545-5979 or your healthcare provider.
Should I take my Zepbound pen out of the fridge before injecting so it is not cold?
You do not have to. The pen's Instructions for Use says "It is not necessary to warm the pen to room temperature", and time spent out counts toward the room-temperature total.
How do I throw away a used pen, KwikPen, vial or needle?
The KwikPen Instructions for Use says used pen needles go "in an FDA-cleared sharps disposal container right away after use", and the KwikPen itself goes in household trash or a sharps container once the needle is off.
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