FDA approves 21-day in-use storage for single-dose tirzepatide

The Food and Drug Administration approved a joint labeling update for Eli Lilly's tirzepatide products, Mounjaro and Zepbound, allowing single-dose vials and pre-filled syringes to be stored for up to 21 days with repeated switching between refrigeration and room temperature ^[1]. The approval, dated April 22, 2026, applies to both drugs under NDA 215866/S-052 for Mounjaro and NDA 217806/S-050 for Zepbound ^[1].

Lilly submitted the supplements on March 9, 2026, as "Prior Approval" applications, meaning the FDA had to sign off before the new storage instructions could appear on labels ^[1]. The company ran a stability study cycling drug product between 5°C, refrigerator temperature, and 30°C, a warm room temperature, to see whether repeated temperature swings would degrade the medicine ^[1]. According to the approval letter, Lilly concluded that test results at the start of the cycling phase and again at 21 days "show no practical difference between control versus cycled samples against the acceptance criteria," and that cycling between 5°C and 30°C "had no impact on the drug product critical quality attributes" ^[1]. Based on that data, the FDA agreed that cumulative storage with temperature cycling for 21 days is supported for single-dose vials and semi-finished syringes of tirzepatide ^[1].

The approval also covers draft carton and container labels for all Mounjaro strengths, along with updated prescribing information, a Medication Guide, and separate instructions for use for both the vial and the single-dose pen ^[1]. The FDA's letter was signed by Nina Ni, Ph.D., of the agency's Division of Product Quality Assessment VII, on behalf of the review team ^[1].

Why it matters for patients

GLP-1 injectable drugs like tirzepatide have historically required careful refrigeration, which can complicate travel, work schedules, or situations where a reliable fridge is not always at hand. This approval does not change the medicine's ingredients or dosing; it changes how long the product can safely sit outside the refrigerator, including going back and forth, before it must be used or discarded ^[1]. Because the letter approves the labeling changes for single-dose vials and semi-finished syringes specifically, it is not yet clear from this source whether the same 21-day cycling allowance applies to Lilly's other tirzepatide pen formats or to any other GLP-1 products, including semaglutide-based Ozempic, Wegovy, or Rybelsus, or to orforglipron under the brand Foundayo. Patients who currently follow stricter refrigeration instructions on their existing packaging should note that label updates take time to reach pharmacies and product inserts.

What happens next

The FDA's letter sets several administrative deadlines for Lilly following the April 22, 2026 approval. The company must submit the final content of labeling in structured product labeling format within 14 days, by roughly May 6, 2026, so the updated instructions can appear in public labeling repositories ^[1]. Lilly also has 14 days to amend any other pending supplements that include labeling changes so they reflect the newly approved storage language ^[1]. Separately, the company has 30 days to submit any required patent information tied to the labeling change for listing in the FDA's Orange Book ^[1], and must submit final printed carton and container labels within 30 days after they are printed, though FDA approval of those printed labels is not required before they are used ^[1]. The letter does not specify exactly when updated packaging bearing the new 21-day storage instructions will reach pharmacies, so patients may see a transition period during which older labeling remains in circulation.