Sources last read 2026-08-12

Mounjaro side effects

Mounjaro’s label reports nausea in 12, 15 and 18 of every 100 adults on 5, 10 and 15 mg, against 4 on placebo.

Source for this answer

Source: Read from the Mounjaro label, revision 08/2026

Medically reviewed by Jennifer Montecillo, MD · non-practicing medical reviewerReviewed 2026-08-12every number here is sourced

The two placebo-controlled diabetes trials in adults

Read the placebo column first. Nearly everything below also happened to some people on placebo. The gap between columns is the part linked to the drug in these trials.

Trial armsPlacebo: n = 235Mounjaro 5 mg: n = 237Mounjaro 10 mg: n = 240Mounjaro 15 mg: n = 241

The two placebo-controlled diabetes trials in adults
Side effect	Placebo	Mounjaro 5 mg	Mounjaro 10 mg	Mounjaro 15 mg
Nausea	4%	12%	15%	18%
Diarrhea	9%	12%	13%	17%
Appetite loss	1%	5%	10%	11%
Vomiting	2%	5%	5%	9%
Constipation	1%	6%	6%	7%
Indigestion	3%	8%	8%	5%
Belly pain	4%	6%	5%	5%

Who was in the trials: 718 adults with type 2 diabetes took Mounjaro across SURPASS-1 and SURPASS-5. The average age was 58 and people had had diabetes for about 9 years.
How long: An average of 36.6 weeks on the drug
What made the table: Everything reported by 5 in 100 people or more, and more often than on placebo. Low blood sugar is counted separately.
Who stopped: Across the wider pool of seven trials in 5,119 adults, the label says the kinds and rates of common side effects matched the table above.

The trial in patients aged 10 and older

Trial armsPlacebo: size not publishedMounjaro 5 mg: size not publishedMounjaro 10 mg: size not published

The trial in patients aged 10 and older
Side effect	Placebo	Mounjaro 5 mg	Mounjaro 10 mg
Vomiting	3%	16%	12%
Belly pain	9%	22%	15%

Who was in the trials: 97 young patients with type 2 diabetes took Mounjaro. The average age was 15, 61% were girls, and most were also on metformin, background insulin, or both.
How long: An average of 39.9 weeks, with a 30-week placebo-controlled stretch
What made the table: The label prints only the effects that came up more often here than in adults
Who stopped: No episode of severe low blood sugar was reported during the trial. The label does not publish arm sizes for this table, so the columns above carry percentages without them.

The boxed warning: thyroid tumors in rodents

Like every drug in this family, Mounjaro opens with a boxed warning drawn from rat studies that found thyroid C-cell tumors. The human risk is unknown. Anyone with medullary thyroid cancer in the family, or with the inherited condition MEN 2, is ruled out by the label.

What does the label tell prescribers to watch for?

These warnings sit above the table in the label. They cover uncommon problems that matter most.

Warnings and precautions from the Mounjaro FDA label
Warning	What this label says about it
Pancreatitis	The warning was rewritten in December 2025 to match the rest of the GLP-1 family.
Low blood sugar	The clearest risk here, because most people on Mounjaro are also taking other diabetes medicines.
Diabetic eye disease	Fast improvement in blood sugar can make existing eye damage worse.
Kidney injury	Usually after fluid loss from being sick or having diarrhea.
Severe stomach and gut problems	Rewritten in December 2025 alongside the pancreatitis warning.
Gallbladder disease	Reported by 0.6 in 100 adults on Mounjaro and none on placebo.
Serious allergic reactions	More common in people who developed antibodies to the drug.
Breathing in stomach contents under anesthetic	The label warns that the stomach may not be empty.

What matters first

Highest listed reaction: Belly pain: 22% in Mounjaro 5 mg
Distinct reactions listed: 7
Warnings to watch: 8
Boxed warning: The boxed warning: thyroid tumors in rodents

What have people actually reported about Mounjaro?

93,975 reports naming Mounjaro have reached the FDA’s public database. A report is not proof the drug caused anything, and there is no way to know how many people took it.

Most reported terms for Mounjaro in openFDA FAERS, retrieved 2026-08-17
Most reported	Reports	Share of Mounjaro reports
Wrong dose given	17,026 reports	18% of Mounjaro reports
Nausea	9,613 reports	10% of Mounjaro reports
Injection site pain	9,193 reports	9.8% of Mounjaro reports
Off label use	7,824 reports	8.3% of Mounjaro reports
Diarrhea	5,925 reports	6.3% of Mounjaro reports
Extra dose given	5,116 reports	5.4% of Mounjaro reports
Vomiting	5,114 reports	5.4% of Mounjaro reports
Constipation	3,635 reports	3.9% of Mounjaro reports
Injection site hemorrhage	3,540 reports	3.8% of Mounjaro reports
Injection site erythema	3,094 reports	3.3% of Mounjaro reports

FDA reports include dosing errors and symptoms such as pain at the injection site. A ranking of these entries is a ranking of reports, not a risk comparison.

The brand-level counts do not separate every device or explain why an event happened. They cannot establish that a specific presentation caused it.

No count of everyone treated. FAERS counts submitted reports, not everyone who used a drug. Each percentage here divides an event count by the drug’s report total. It describes a share of reports, not a share of people treated or their chance of an event.
A report is not proof the drug did it. FDA does not require proof that a drug caused an event before accepting a report. The drug, an illness or another factor may be involved. A report naming both a drug and an event does not establish the cause.
A bigger number can just mean a more-prescribed drug. More reports can simply mean that more people use the drug, that it is newer, or that it receives more news and legal attention. Raw report totals do not tell you which drug is safer.
The same event can be counted twice. One event can reach FAERS through more than one channel — the patient, the prescriber and the manufacturer can all file. FDA does not guarantee that the public files are de-duplicated.
Retrieved 2026-08-17 from https://api.fda.gov/drug/event.json. FDA disclaimer: Do not rely on openFDA to make decisions regarding medical care. While we make every effort to ensure that data is accurate, you should assume all results are unvalidated. We may limit or otherwise restrict your access to the API in line with our Terms of Service.

4Interpret the pageDose patterns, same-drug context, and where the evidence continues

Young patients had a rougher time than adults

The label says side effects in patients aged 10 and older matched the adult picture with three exceptions: vomiting, belly pain and low blood sugar all came up more often.

Vomiting hit 16 in every 100 on 5 mg, against 3 on placebo. Belly pain hit 22 in every 100 on 5 mg, against 9 on placebo. Both are well above what the adult table shows at the same dose.

No severe low blood sugar was reported. That is the reassuring half of the same finding, and both halves come from one 99-patient trial, which is small.

Antibodies changed who reacted at the injection site

Some people make antibodies to tirzepatide. The label reports what happened next, split by whether they did.

Among adults who developed antibodies, 4.6 in every 100 had a reaction where they injected. Among those who did not, it was 0.7. Allergic reactions split the same way, 4.1 against 3.0.

The label does not say the antibodies caused this. It publishes the split and leaves it there, which is the correct way to handle a finding with no trial designed to test it.

Why do Mounjaro and Zepbound report different numbers for the same drug?

Both are tirzepatide. The percentages differ because the trials behind them differ, not because one product is gentler than the other.

Each label opens its table with the same warning: rates from one drug’s trials cannot be set against another’s. That holds here even though the drug substance is identical. The two sets of trials enrolled different people. They ran to different doses. And they used different cut-offs for what got printed at all.

The Zepbound side-effect table in full

Where to read next

Two pages carry the parts this one leaves out.

The Mounjaro dose schedule has the step pattern these percentages are attached to.
Side effects of tirzepatide itself covers the drug across every product built on it.

Questions readers ask

What should I avoid while taking Mounjaro?

The label’s own don’ts are short. Never share a pen. Tell an anesthetist before a procedure, because the stomach may not be empty.

It also flags insulin and sulfonylureas as the combination that raises low blood sugar risk, and says those doses may need cutting. The label names no food or drink to avoid.

What's safer, Ozempic or Mounjaro?

SURPASS-2 assigned 1,879 adults with type 2 diabetes to separate groups: tirzepatide 5, 10 or 15 mg, or semaglutide 1 mg. It does not establish which drug is safer for a particular person.

Nausea affected 17 to 22 in 100 in the tirzepatide groups, against 18 on semaglutide. Serious health events were reported in 5 to 7 in 100 against 3.

These counts do not mean the drugs caused every event. These results do not cover Ozempic 2 mg.

What are the worst side effects of taking Mounjaro?

By frequency, nausea leads at 12, 15 and 18 in every 100 adults on 5, 10 and 15 mg. Placebo was 4. Diarrhea, appetite loss, vomiting and constipation follow.

By seriousness the list is different: pancreatitis, gallbladder disease, kidney injury after fluid loss, and the boxed warning about thyroid C-cell tumors seen in rodents.

What are the long-term effects of Mounjaro?

The August 2026 label includes SURPASS-CVOT, a heart-outcome trial with follow-up lasting about four years. It enrolled adults with type 2 diabetes and existing heart or blood vessel disease.

The common side-effect table comes from shorter diabetes trials, with an average of 36.6 weeks on Mounjaro. It is not a four-year side-effect rate. Different trial groups and follow-up periods answer different questions.

1primary source, each with the day we read it — open the documents used on this page

MOUNJARO (tirzepatide) injection — DailyMed SPL, sections 5, 6.1, 8.4 and 14.6retrieved 2026-09-13FDA label

Beyond the Mounjaro reaction table

Where Mounjaro sits against the other three

What each label approves, for whom, and where its schedule stops, with Mounjaro as context

The Mounjaro price with a plan that covers it

Every Mounjaro card here shuts out Medicare and Medicaid, quoted from the terms rather than paraphrased.

Start with the Mounjaro overview

Mounjaro is Tirzepatide, with 3 approved uses on its own FDA label.

Where Mounjaro lands in Mounjaro vs Zepbound

11 rows read from both labels for Mounjaro vs Zepbound, independently of Mounjaro.

The Mounjaro half of Wegovy vs Mounjaro

Also asked as Mounjaro vs Wegovy: one question, one page, and no second URL for Mounjaro.

Mounjaro vs Ozempic, with Mounjaro on one side of it

SURPASS-2 behind Mounjaro vs Ozempic: 1,879 adults, counted apart from Mounjaro.