What are the most common side effects of Mounjaro?

The label lists nausea, diarrhea, decreased appetite, vomiting, constipation, indigestion and others among reactions reported in at least 5% of patients. The full frequency table is in the label itself, linked below; any percentage quoted on this page is the label's own figure.

Do the side effects mean the price is not the issue?

They meet at titration. Most of these reactions are worst in the weeks after a dose increase, and those are also the weeks when some sellers charge a lower starting price. So the months people are most likely to stop are not the months that show what the drug costs. The maintenance price is on the Mounjaro price page.

← Mounjaro (tirzepatide, diabetes label)

Mounjaro (tirzepatide, diabetes label) side effects

Mounjaro's FDA label lists 7 common reactions, 8 serious warnings and 2 contraindications, plus a boxed warning. All of them are below in the label's own order; any percentage is the label's own figure, and nothing here is a recommendation.

No clinician has reviewed this page. Label and trial statements are quoted from the FDA label or the trial cited beside them. General guidance is marked as such, and every price carries the date it was verified. That is sourcing, not medical review. What we do and do not check · Who checked the price

Last updated 2026-09-02 — the version of the FDA label this page quotes. Read and dated by Alex Seot.

What are the side effects of Mounjaro?

The FDA label for Mounjaro lists nausea, diarrhea, decreased appetite, vomiting and constipation among the reactions reported in at least 5% of patients. It carries a boxed warning, the strongest the FDA issues: In rodents this molecule caused thyroid C-cell tumors at human-relevant doses. The label's serious warnings include acute pancreatitis; hypoglycemia with an insulin secretagogue or insulin; hypersensitivity reactions including anaphylaxis and angioedema; and acute kidney injury from volume depletion. It is contraindicated in 2 cases, among them a personal or family history of medullary thyroid carcinoma, or MEN 2, meaning the label says not to prescribe it at all. Every line above is quoted from FDA prescribing information for MOUNJARO rather than summarized from a secondary source, because a side-effect list paraphrased twice stops being the label. That label version was published 2026-09-02. Frequencies are not repeated here second-hand: the percentage table lives in the label itself, which is linked on the page.

Boxed warning — the strongest warning the FDA issues

In rodents this molecule caused thyroid C-cell tumors at human-relevant doses. Whether it does so in people is unknown, and the label carries that as a boxed warning. It is contraindicated outright with a personal or family history of medullary thyroid carcinoma or MEN 2.

Common, and usually manageable

Reactions the label reports in at least 5% of patients.

nausea
diarrhea
decreased appetite
vomiting
constipation
indigestion
abdominal pain

Same molecule and the same pen strengths as Zepbound, on the diabetes label, but a different schedule. Mounjaro goes up from 2.5 mg only if glucose control needs it, in 2.5 mg steps at least 4 weeks apart, and stops at 10 mg for children 10 and older. Gastrointestinal reactions made 3.0% of adults stop at 5 mg, 5.4% at 10 mg and 6.6% at 15 mg, against 0.4% on placebo, and most nausea, vomiting and diarrhea comes during dose escalation and eases over time. Side effects that do not settle are a conversation with the prescriber rather than a reason to quit unannounced.

Serious, and worth knowing before you start

Acute pancreatitis, including fatal and non-fatal hemorrhagic or necrotizing pancreatitis: persistent or severe abdominal pain, sometimes radiating to the back. The label says to stop the drug if it is suspected
Hypoglycemia with an insulin secretagogue or insulin: the label says the sulfonylurea or insulin dose may need lowering
Hypersensitivity reactions including anaphylaxis and angioedema, which the label says are a reason to stop and not to use it again
Acute kidney injury from volume depletion, in some cases needing dialysis, reported mostly in people who became dehydrated through nausea, vomiting or diarrhea
Severe gastrointestinal reactions: 1.3% at 5 mg, 0.4% at 10 mg and 1.2% at 15 mg against 0.9% on placebo in the pooled adult trials. Not recommended in severe gastroparesis
Diabetic retinopathy complications in people with a history of diabetic retinopathy, because rapid improvement in glucose control can temporarily worsen it
Acute gallbladder disease: cholelithiasis, biliary colic or cholecystectomy in 0.6% of Mounjaro-treated adults against 0% on placebo
Pulmonary aspiration during general anesthesia or deep sedation: the drug delays gastric emptying, and stomach contents have been found despite normal preoperative fasting. Tell any surgeon or anesthesiologist you are taking it
Never share a KwikPen between patients, even with a new needle (5.10) — sharing risks passing on blood-borne infection

Who cannot take it

A personal or family history of medullary thyroid carcinoma, or MEN 2
Known serious hypersensitivity to tirzepatide

Each of these, on its own

What the label says, why it happens, how it tracks the dose schedule and the point at which it stops being ordinary.

What it costs Dosage schedule

Everything on Mounjaro

Questions

What are the most common side effects of Mounjaro?: The label lists nausea, diarrhea, decreased appetite, vomiting, constipation, indigestion and others among reactions reported in at least 5% of patients. The full frequency table is in the label itself, linked below; any percentage quoted on this page is the label's own figure.
Who should not take it?: The label contraindicates it in these cases: A personal or family history of medullary thyroid carcinoma, or MEN 2; Known serious hypersensitivity to tirzepatide.
Do the side effects mean the price is not the issue?: They meet at titration. Most of these reactions are worst in the weeks after a dose increase, and those are also the weeks when some sellers charge a lower starting price. So the months people are most likely to stop are not the months that show what the drug costs. The maintenance price is on the Mounjaro price page.

Source: FDA prescribing information for MOUNJARO, the version published 2026-09-02. Information only, not medical advice: a side effect you are having is a conversation with your prescriber, not with a comparison site.