There's no single number, because compounded tirzepatide has no FDA label. Read the dispensing pharmacy’s storage instructions and beyond-use date, and ask about any missing or conflicting information. They do not establish that Zepbound’s room-temperature allowance applies to your preparation. Two different source-specific limits are Zepbound's 21-day room-temperature allowance, and FDA's 28-day rule for opened multi-dose vials. The drug itself is explained in the compounded tirzepatide guide.
Read the preparation-specific label and resolve any conflict with FDA advice
The label on a compounded vial carries a beyond-use date, set by the pharmacy that made it. Compounded drugs do not undergo FDA premarket review of safety, effectiveness or quality. A pharmacy’s beyond-use assignment is therefore not an FDA-approved expiration date [1]. State boards generally have primary day-to-day oversight of state-licensed pharmacies that are not FDA-registered outsourcing facilities; FDA can still conduct surveillance and for-cause inspections [3].
Read the storage line as well as the date. It tells you whether the vial must stay refrigerated and whether any time out of the fridge is allowed. If the label is silent, ask before you assume. FDA tells patients to contact "the compounder who made the drug or the telehealth platform where you purchased the drug" with any question about the label [1].
What Zepbound's label allows, for comparison
Zepbound provides a brand-specific comparison, whose limits apply to Lilly’s own products and do not establish the stability of a pharmacy preparation. Its single-dose pens and vials can be stored unrefrigerated, at no more than 86°F (30°C), "for up to a total of 21 days" [2]. Its multi-dose vials and KwikPens follow a 30-day clock.
| Product | In the fridge | Out of the fridge | After first use | Source |
|---|---|---|---|---|
| Zepbound single-dose pen or vial | 36°F to 46°F (2°C to 8°C) | Up to 21 days total, at no more than 86°F (30°C) | Single dose | Zepbound label [2] |
| Zepbound multi-dose vial or KwikPen, unopened | Until the expiration date | Throw away after 30 days at up to 86°F (30°C) | Not yet opened | Zepbound label [2] |
| Zepbound multi-dose vial or KwikPen, opened | Fridge or room temperature up to 86°F (30°C) | Counts toward the 30 days | Throw away after 30 days at room temperature, 30 days after first use, or 4 weekly doses | Zepbound label [2] |
| Compounded tirzepatide, multi-dose vial | Follow specified temperature and beyond-use limits; confirm any excursion | Only as the pharmacy label allows | Discard 28 days after first use, even if the label says longer | Pharmacy label; FDA [1] |
| Any injectable GLP-1 that arrives warm | Not applicable | Don't use it | Not applicable | FDA [1] |
Zepbound label version 40 on DailyMed; FDA's GLP-1 page current as of October 1, 2026.
FDA's 28-day rule for opened vials
Once you've used a multi-dose vial, FDA's advice is simple: it's done 28 days later, whatever is left. The reason, FDA says, is a higher risk of contamination after 28 days.
Generally, FDA recommends that vials containing multiple doses of sterile medications be used within 28 days after the first use because there is an increased risk of contamination after 28 days.[1]
FDA goes further for compounded GLP-1s: "Do not continue using medication from the vial after 28 days, even if instructions from the compounder say the medication can be used for longer than 28 days" [1]. So if your pharmacy's label allows longer, FDA's advice is the stricter one to follow. Mark the date of your first dose on the box.
If it arrived warm, don't use it
FDA says injectable GLP-1 drugs "require refrigeration as indicated in their package inserts," and it has received complaints of compounded GLP-1s arriving warm or with too little ice [1]. Its advice is not to use any injectable GLP-1 "that arrives warm or with insufficient refrigeration, as this can affect the drug's quality." Contact the pharmacy or program for a replacement. How a program handles cold-chain shipping is worth checking before you sign up; where to get compounded tirzepatide covers what to ask.
Freezing is a problem too. Zepbound's label says "Do not use ZEPBOUND if frozen" [2]. A compounded label may say the same; if yours doesn't mention freezing, call the pharmacy before using a vial that froze.
Does compounded tirzepatide expire?
Yes. The beyond-use date is a limit under the specified storage conditions, not a guarantee that every vial remains suitable until that date. A temperature excursion or suspected contamination still needs assessment. After the first dose, the earlier of two dates applies: the label's date, or 28 days from first use. Time spent out of the fridge can shorten that further if the label limits it.
Signs it's time to call your pharmacist
Zepbound should look "clear and colorless to slightly yellow," and its label says not to use it if particles or discoloration appear [2]. A compounded product may differ in color or contents, so compare it with the dispensing pharmacy’s description. Normal appearance alone cannot prove potency, sterility or suitability. FDA lists medicine that "looks different than what you've previously received" among its red flags [1]. If anything looks off, ask before you use it.
How long tirzepatide lasts in your body
Some people asking "how long does it last" mean in the body. Zepbound's label puts tirzepatide's elimination half-life at about 5 to 6 days, which is why it's given once a week [2]. Starting doses and schedules are covered in the compounded tirzepatide starting dose, and the brand-versus-compounded differences in compounded tirzepatide vs Zepbound. If you also keep semaglutide, its rules differ: see how long compounded semaglutide lasts in the fridge.