Drug facts

Storage and beyond-use dating

Reviewed August 2026

Quick answer

The approved product is stored in a refrigerator at 2 °C to 8 °C (36 °F to 46 °F), and it may be kept at room temperature up to 30 °C (86 °F). How long depends on which container you have: 21 days for a single-dose pen or single-dose vial, 30 days for a multi-dose vial or a single-patient-use KwikPen. If it has been stored above 30 °C, the label says do not use it.

The approved storage range1

Refrigerated

Temperature
2 °C – 8 °C (36 °F – 46 °F)
How long
Until the printed expiration date

Room temperature — single-dose pen or vial

Temperature
Up to 30 °C (86 °F)
How long
Up to 21 days, total
If exceeded
Do not use.

Room temperature — multi-dose vial or KwikPen

Temperature
Up to 30 °C (86 °F)
Unopened
Throw away after 30 days
Once opened
Throw away after 30 days at room temperature, 30 days after first use, or after four weekly doses — whichever comes first, even if there is medicine left in it.
If exceeded
Do not use.

Both clocks are totals, not a fresh allowance each time. Once the product has been out of the refrigerator, putting it back does not reset them.

Which number applies to you is worth getting right, because the two containers are not interchangeable. The 21-day figure is the one repeated most often online, and it is the one for a single-dose pen — which is not what a compounded seller ships. A compounded preparation almost always arrives as a multi-dose vial you draw several weeks of doses from, so the rules to read across are the 30-day ones, with the caveat in the next section: a compounded vial is not the approved product, and these figures describe the approved product.

Why a compounded vial is different1

On the label — Mounjaro / Zepbound

Carries an expiration date supported by stability data that FDA reviewed as part of approving the product.

In a compounded vial

Carries a beyond-use date instead. That is a date the compounding pharmacy assigns based on how the preparation was made and stored — a different kind of claim, resting on the pharmacy’s own standards rather than on an FDA-reviewed stability program for that exact preparation. Beyond-use dates are frequently much shorter than an approved product’s expiry, and they vary between pharmacies.

This is the clearest everyday example of what “no label” actually means. There is no single answer to how long a compounded vial keeps, because the answer belongs to the pharmacy that made yours and is printed on your own label.

If your vial has been out of the fridge1

For the approved product the label is explicit: above 30 °C, do not use it. For a compounded vial, the equivalent limit is whatever your pharmacy specified, and the honest answer is that we cannot tell you what that is. Call them. A pharmacy would far rather replace a vial than have you use one that has been too warm.

What we can tell you is that a price comparison is not the place to settle a question about whether a specific vial is still safe — see the medical disclaimer.

Sources

  1. FDA prescribing information for ZEPBOUND (tirzepatide), section 16, revision 4/2026 DailyMed