Package insert and Medication Guide updates approved for both brands

On September 25, 2025, the FDA processed labeling supplements for both of Eli Lilly's tirzepatide medicines on the same date. Mounjaro, approved under New Drug Application (NDA) 215866, received supplement S-034, categorized as "Labeling-Package Insert, Labeling-Medication Guide" ^[1]. Zepbound, approved under NDA 217806, received supplement S-031, carrying the identical labeling categories ^[2]. Both actions are recorded in the FDA's Drugs@FDA database, which tracks approvals, letters, and labels for each drug application ^[1][2].

Mounjaro was first approved on May 13, 2022, and has since gone through more than a dozen supplements covering packaging, dosing, indications, and labeling ^[1]. Zepbound, approved on November 8, 2023, has had a similar string of updates, including a December 20, 2024 supplement for a new indication and a February 7, 2025 supplement for package insert and container/carton labeling changes ^[2]. The September 25, 2025 actions for both drugs fit into this ongoing pattern of periodic label revisions that Lilly has filed as the company gathers more safety and use data.

The FDA's public tracking pages list the submission number, the date the agency acted, and the general category of the change, such as "Labeling-Medication Guide" or "Labeling-Package Insert." They link to the full label PDFs but do not summarize, in the tracking table itself, what specific sentences or warnings were added, removed, or reworded ^[1][2]. Based on the available records, it is not yet known exactly what content changed in the Mounjaro or Zepbound package inserts or Medication Guides as part of these September 2025 supplements.

Why it matters for patients

The package insert is the detailed prescribing information doctors and pharmacists use, while the Medication Guide is the plain-language document patients often receive when a pharmacy fills a new or refilled prescription. When the FDA approves updates to either document, it usually means the agency and the manufacturer have agreed to revise how risks, side effects, dosing, or use instructions are described. For people currently taking Mounjaro or Zepbound, a labeling supplement like this does not by itself change how the drug is manufactured or dosed, but it can affect what information appears in future printed or digital versions of the guide handed out with a prescription. Because the source records here confirm only that a labeling change occurred, not its content, patients who want specifics would need to check the linked label documents directly or ask a pharmacist whether the version they receive reflects the September 2025 update.

What happens next

Both drugs have continued to accumulate labeling activity after September 2025. Mounjaro's record shows a further supplement on December 19, 2025 for a new patient population, a packaging-related supplement on January 7, 2026, and another Medication Guide and package insert update on January 20, 2026, followed by supplements tied to a new indication and a new dosing regimen dated August 27, 2026 ^[1]. Zepbound's record shows a formulation-related supplement on January 7, 2026, a package insert, container label, and Medication Guide update on January 20, 2026, a package insert supplement on February 25, 2026, and an efficacy-related labeling change with clinical data dated August 26, 2026 ^[2]. These later entries indicate the FDA and Lilly have kept revising both labels well beyond the September 2025 action, though, as with the September update, the tracking tables do not describe the substance of those later changes.