Boxed warning: risk of thyroid C-cell tumors. In rodent studies, tirzepatide caused thyroid C-cell tumors. It is not known whether it causes these tumors, including medullary thyroid carcinoma, in humans. Mounjaro must not be used by anyone with a personal or family history of medullary thyroid carcinoma (MTC), or by anyone with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).
Serious risks in the prescribing information include pancreatitis, gallbladder problems, low blood sugar (particularly with insulin or a sulfonylurea), serious allergic reactions, acute kidney injury from dehydration, diabetic retinopathy complications, and food remaining in the stomach during general anesthesia or deep sedation.
The most common side effects are nausea, diarrhea, decreased appetite, vomiting, constipation, indigestion and abdominal pain (Eli Lilly, Mounjaro prescribing information). They are usually worst in the first weeks and after each dose increase, then ease as tolerance develops. The four-week interval between increases exists for that reason.
Tell your prescriber before starting if you have had pancreatitis, have a history of gallbladder disease, have diabetic retinopathy, have kidney disease, have any severe gastrointestinal condition including gastroparesis, are taking insulin or a sulfonylurea, are pregnant or planning pregnancy, or are breastfeeding. Tirzepatide can also reduce the effectiveness of oral contraceptives, so if you use one, ask about a backup method during the first weeks and after each dose increase.
Tell any surgeon or anesthesiologist that you take tirzepatide well before a procedure. Slowed gastric emptying means food can remain in the stomach longer than expected under general anesthesia or deep sedation. This is a summary, not the full label. Read the complete prescribing information and medication guide, and our Mounjaro safety information.