Tirzepatide labeling changed to add ileus, alongside a similar semaglutide change

In July 2023, labeling for tirzepatide (Mounjaro) was changed to reflect ileus — a slowdown or blockage of movement through the intestines. The change came about two months before FDA added ileus to the semaglutide (Ozempic) label in September 2023. Both updates were driven by reports submitted after the drugs were on the market, not by findings from the randomized trials used for approval.

That distinction matters for how the information reads. Postmarketing sections of a US drug label are built from voluntary reports from a population of uncertain size, so labels typically state that it is not always possible to reliably estimate how often the event happens or to establish a causal link to the drug. That is why no percentage appears next to ileus, unlike the side effects measured in trials.

What the label says now

The sources available here are limited to the current DailyMed listing for Mounjaro and Mounjaro KwikPen, last revised 8/2026 ^[1]. That label's "Recent Major Changes" table only lists updates going back to December 2025 and August 2026, so the 2023 ileus change is no longer displayed there — a normal feature of how these tables roll forward over time ^[1].

What the current label does show is a broad emphasis on gastrointestinal effects. Tirzepatide carries a Warnings and Precautions section on Severe Gastrointestinal Adverse Reactions, updated 12/2025, which states that use "has been associated with gastrointestinal adverse reactions, sometimes severe," and that Mounjaro "is not recommended in patients with severe gastroparesis" ^[1]. The label also notes that tirzepatide delays gastric emptying and has the potential to affect absorption of other oral medications taken at the same time ^[1].

The most common adverse reactions reported in at least 5% of patients taking Mounjaro are nausea, diarrhea, decreased appetite, vomiting, constipation, dyspepsia and abdominal pain ^[1]. Other warnings include acute pancreatitis, hypoglycemia when combined with insulin or insulin secretagogues, serious hypersensitivity reactions, acute kidney injury from volume depletion, acute gallbladder disease, diabetic retinopathy complications in people with a history of retinopathy, and pulmonary aspiration during general anesthesia or deep sedation ^[1]. Tirzepatide also carries a boxed warning about thyroid C-cell tumors seen in rats, and is contraindicated in people with a personal or family history of medullary thyroid carcinoma or with Multiple Endocrine Neoplasia syndrome type 2 ^[1].

Why it matters for patients

Ileus sits at the severe end of the gastrointestinal effects that are already the most common complaints with these drugs. Because it entered both the tirzepatide and semaglutide labels through postmarketing surveillance, there is no trial-derived rate telling patients how likely it is. The honest answer is that the frequency is not known from these sources.

Practically, the label change means prescribers and pharmacists have formal notice of the risk, and it gives clinicians a documented reason to take persistent abdominal pain, vomiting, constipation or bloating seriously rather than treating every symptom as routine startup nausea. It also underscores why the label separately flags severe gastroparesis and delayed stomach emptying ^[1].

Patient and clinician reports feed this system. The label directs suspected adverse reactions to Eli Lilly at 1-800-LillyRx (1-800-545-5979) or to FDA at 1-800-FDA-1088 or www.fda.gov/medwatch ^[1].

What happens next

Labels continue to change. For tirzepatide, the severe gastrointestinal reactions section was revised in December 2025, and further updates to indications, dosing and the retinopathy warning were made in August 2026 ^[1]. Whether the ileus language itself has been reworded since 2023 is not established by the sources available here. Anyone weighing these medicines can check the current prescribing information on DailyMed, which posts the most recent version ^[1].