Mounjaro (Tirzepatide) and Vomiting: When to Call the Doctor

How often does Mounjaro cause vomiting?

The Mounjaro label pools two placebo-controlled trials in adults with type 2 diabetes, SURPASS-1 (tirzepatide alone) and SURPASS-5 (added to basal insulin), covering 718 patients treated with Mounjaro and a mean exposure of 36.6 weeks [1]. Vomiting was reported by 2% of the 235 patients on placebo, 5% of the 237 on 5 mg, 5% of the 240 on 10 mg and 9% of the 241 on 15 mg [1]. Nausea (12%, 15% and 18% at 5, 10 and 15 mg vs 4% on placebo) and diarrhea (12%, 13% and 17% vs 9%) were reported at similar or higher rates [1].

Any GI adverse reaction was reported by 37.1%, 39.6% and 43.6% of patients on 5, 10 and 15 mg, against 20.4% on placebo, and GI side effects led to discontinuation in 3.0%, 5.4% and 6.6% versus 0.4% [1]. Severe gastrointestinal reactions were reported by 1.3%, 0.4% and 1.2% versus 0.9% [1]. The label notes that the majority of reports of nausea, vomiting and/or diarrhea occurred during dose escalation and decreased over time [1].

Head-to-head data come from SURPASS-2, a 40-week open-label trial of 1,879 adults with type 2 diabetes on metformin: vomiting was reported by 6% to 10% of patients on tirzepatide 5, 10 or 15 mg and by 8% of those on semaglutide 1 mg [2]. The label cautions that adverse reaction rates from different trials cannot be directly compared [1].

What the label says about the dosing schedule

Treatment starts at 2.5 mg once weekly and rises in 2.5 mg steps after at least 4 weeks on the current dose, only if more glycemic control is needed, to a maximum of 15 mg weekly in adults and 10 mg weekly in pediatric patients 10 years of age and older [1]. The label says to follow the starting dosage and escalation schedule to reduce the risk of gastrointestinal adverse reactions [1]. It also notes that tirzepatide delays gastric emptying, that the delay is largest after the first dose and diminishes over time [1].

When to call the doctor about vomiting

The label does not give a number of vomiting episodes that should trigger a call. Its warnings describe the complications that turn vomiting from an inconvenience into a medical problem.

You cannot keep fluids down

Postmarketing reports describe acute kidney injury, in some cases requiring hemodialysis, in patients on GLP-1 receptor agonists including Mounjaro; most of the reported events occurred in patients who had gastrointestinal reactions leading to dehydration such as nausea, vomiting or diarrhea [1]. The label says to monitor renal function in patients reporting reactions that could lead to volume depletion, especially during initiation and dose escalation [1].

Severe or persistent abdominal pain

The label says to watch for signs and symptoms of acute pancreatitis, which may include persistent or severe abdominal pain, sometimes radiating to the back, and which may or may not be accompanied by nausea or vomiting [1]. If pancreatitis is suspected, the label says to discontinue Mounjaro and begin appropriate management [1].

Possible gallbladder disease

Acute gallbladder disease (cholelithiasis, biliary colic or cholecystectomy) was reported by 0.6% of Mounjaro-treated patients and 0% of placebo patients in the adult placebo-controlled trials [1]. The label says gallbladder studies and clinical follow-up are indicated if cholelithiasis is suspected [1].

Low blood sugar if you take insulin or a sulfonylurea

Mounjaro raises the risk of hypoglycemia, including severe hypoglycemia, when used with insulin or an insulin secretagogue such as a sulfonylurea, and the label says lowering the dose of the insulin or secretagogue may be necessary [1].

Signs of a serious allergic reaction

Anaphylaxis and angioedema have been reported with Mounjaro [1]. The label says to discontinue the drug if a hypersensitivity reaction is suspected and to promptly seek medical advice [1].

Known gastroparesis

Mounjaro is not recommended in patients with severe gastroparesis [1].