Mounjaro and Zepbound Side Effects by Dose

The Mounjaro side effects listed most often on the US label are gastrointestinal: nausea, diarrhea, decreased appetite, vomiting and constipation, plus injection site reactions. Zepbound, which is the same medicine (tirzepatide) labelled for weight management, lists a similar group that also includes abdominal pain.

On the Zepbound label, nausea affected 25% to 29% of adults on 5, 10 or 15 mg in the weight trials, against 8% on placebo. On the Mounjaro label, in type 2 diabetes trials, it affected 12% to 18% against 4% on placebo. Both labels carry the same boxed warning about thyroid C-cell tumors found in rats, and a short list of rare serious warnings with signs that need a doctor. Every percentage below is given by drug, dose and trial population, and never merged.

In short

• The Zepbound label reports nausea in 25%, 29% and 28% of adults on 5, 10 and 15 mg in its weight trials, against 8% on placebo.
• The Mounjaro label reports nausea in 12%, 15% and 18% on 5, 10 and 15 mg in type 2 diabetes trials, against 4% on placebo.
• Both FDA labels carry a boxed warning about thyroid C-cell tumors in rats, whose relevance to humans is unknown.

What does this guide answer?

This guide answers eight questions about tirzepatide side effects, using the FDA labels for Zepbound and Mounjaro, the SURMOUNT-1 trial and the EU product information for Mounjaro. Read them in order, or jump to the one that matches your symptom.

• What are the most common side effects, and how are the label figures built?
• How common is nausea, and every other gastrointestinal effect, at each dose?
• How common are injection site reactions?
• Do gastrointestinal effects dominate the list, and do rates climb with the dose?
• Which serious warnings are on the label, and which signs mean calling a doctor?
• What does the thyroid C-cell tumor boxed warning say?
• Do the Zepbound and Mounjaro figures differ?
• How do the EU frequency categories compare with the US percentages?

A single table after these sections puts the figures side by side. None of it is personal medical advice, and the prescriber decides what happens with any dose.

What are the most common Mounjaro and Zepbound side effects?

The most common side effects across the Zepbound and Mounjaro labels and the EU product information are nausea, diarrhea, vomiting, constipation, abdominal pain and injection site reactions. Both medicines contain tirzepatide, and the FDA prescribing information for each reports reactions as percentages by dose in placebo-controlled trials.

The two tables are not interchangeable. The Zepbound label covers weight management and pools its Studies 1 and 2, with 958 people on placebo and 630, 948 and 941 on 5, 10 and 15 mg. The Mounjaro label covers type 2 diabetes and pools its adult placebo-controlled trials, with 235 on placebo and 237, 240 and 241 on 5, 10 and 15 mg.

Beyond the gastrointestinal group, the Zepbound table lists fatigue, dyspepsia and hair loss. Fatigue was 3% on placebo and 5%, 6% and 7% on 5, 10 and 15 mg. Dyspepsia was 4% on placebo and 9%, 9% and 10%. Hair loss was 1% on placebo and 5%, 4% and 5%. For fatigue in more depth, see a dedicated guide to fatigue rates on the Zepbound, Wegovy, Mounjaro and Ozempic labels.

Read each figure against placebo. Nausea at 5 mg on Zepbound is 25% and placebo is 8%, so the excess is 25 minus 8, or 17 percentage points. That gap is the share of the rate beyond what placebo produced in those trials.

How common is nausea on Mounjaro and Zepbound, dose by dose?

On the Zepbound label, nausea occurred in 25% of adults on 5 mg, 29% on 10 mg and 28% on 15 mg, against 8% on placebo in the pooled weight-reduction trials. The other gastrointestinal rows follow below, all from the same Zepbound label table.

The chart shows the nausea row on its own.

1. Placebo8%
2. 5 mg25%
3. 10 mg29%
4. 15 mg28%

The numbers in this chart

	Nausea
Placebo	8%
5 mg	25%
10 mg	29%
15 mg	28%

Zepbound FDA prescribing information, section 6.1 Table 1

On the Mounjaro label, the same question has lower answers, and the trials enrolled adults with type 2 diabetes.

Constipation on Zepbound runs the other way from the rest: 17% at 5 mg, 14% at 10 mg and 11% at 15 mg.

The SURMOUNT-1 trial in the New England Journal of Medicine gives single-trial figures for adults with obesity or overweight over 72 weeks. Nausea was 24.6%, 33.3% and 31.0% on 5, 10 and 15 mg against 9.5% on placebo. A symptom log kept day by day can show where your own experience sits among these averages. For food ideas around nausea, see a guide to what to eat on shot day, written for Ozempic, with each label's nausea rates for context.

How common are injection site reactions?

Injection site reactions occurred in 6% to 8% of people on Zepbound in the weight trials, against 2% on placebo, according to the Zepbound label. By dose they were 6% on 5 mg, 8% on 10 mg and 8% on 15 mg.

The Mounjaro label gives one overall figure instead of a dose breakdown: 3.2% on Mounjaro against 0.4% on placebo. The label does not split that rate by dose, so no per-dose number exists to quote.

The arithmetic differs by label. On Zepbound at 15 mg, the excess over placebo is 8 minus 2, or 6 percentage points. On Mounjaro it is 3.2 minus 0.4, or 2.8 points. The Mounjaro rate is eight times the placebo rate (3.2 divided by 0.4), yet the absolute gap is small because placebo was low.

Do not read the lower Mounjaro number as proof that one product is gentler. The figures come from different trials, populations and comparators, so they describe each trial and not a head-to-head result. The EU product information places injection site reactions in the "common" category, which means 1% to under 10%, and both US figures fall inside that range.

A reaction that spreads, worsens or arrives with swelling of the face, lips or throat, or trouble breathing, is a different matter. Those are allergic signs, covered in the serious warnings section below.

Do gastrointestinal side effects dominate the list, and do rates climb with the dose?

Yes, gastrointestinal reactions are the most frequent rows in the Zepbound and Mounjaro tables quoted above. Nausea is the highest row on both labels, at 29% at its peak on Zepbound and 18% on Mounjaro, according to the two FDA labels.

Rates climb with dose in most rows. On Zepbound, diarrhea rises from 19% to 21% to 23% across 5, 10 and 15 mg, and vomiting from 8% to 11% to 13%. On Mounjaro, nausea rises from 12% to 15% to 18%, and decreased appetite from 5% to 10% to 11%.

There are exceptions. Zepbound nausea goes 25%, 29%, 28%, and Zepbound constipation falls with dose. A rate is a trial average, so it need not rise at every step.

The labels report rates by dose step. The Zepbound label's own dose-escalation steps are charted on this site, and the prescriber decides which step applies to you. Lilly's medical information page says gastrointestinal effects occur mostly during dose escalation and ease over time.

Tirzepatide's label half-life is about 5 days, so each step builds up gradually. To see how much may still be active between doses, try the Zepbound half-life calculator or the Mounjaro half-life calculator, for the same estimate on the diabetes-label dosing. For the build-up on one dose, read how Mounjaro's effect and side effects build up over the first weeks on a dose. For comparison with semaglutide, there is a week-by-week decay table for semaglutide.

What serious warnings are on the label, and what signs mean calling a doctor?

The Zepbound and Mounjaro labels list a short set of rare serious warnings, and each comes with signs that mean contacting a doctor. The rates below come from the two FDA labels and the EU product information, and the signs follow the Warnings and Precautions sections of the labels linked in the sources, which you should read in full.

• Pancreatitis. The EU product information lists acute pancreatitis as uncommon (1 in 1,000 to under 1 in 100). Signs: severe stomach pain that does not go away, sometimes reaching the back, with or without vomiting.
• Gallbladder disease. The Zepbound label gives cholelithiasis at 1.1% against 1% on placebo, and cholecystitis at 0.7% against 0.2%. The Mounjaro label gives acute gallbladder disease at 0.6% against 0%. Signs: pain in the upper right or middle stomach, fever, yellowing of the skin or eyes, clay-colored stools.
• Severe gastrointestinal problems. The Zepbound label gives 1.7% to 3.1% by dose against 1% on placebo. Signs: severe stomach problems that persist.
• Kidney injury from dehydration. Vomiting or diarrhea that stops you keeping fluids down can lead to dehydration, which can affect the kidneys. Tell the prescriber if you cannot keep fluids down.
• Allergic reaction. The Mounjaro label gives hypersensitivity at 3.2% against 1.7% on placebo. Anaphylaxis and angioedema are rare in the EU text. Signs: swelling of the face, lips, tongue or throat, trouble breathing, fainting, severe rash. For these, seek emergency help.
• Hypoglycemia. The Zepbound label gives 4.2% against 1.3% (blood glucose under 54 mg/dL) in its type 2 diabetes trial. The EU text rates hypoglycemia as very common with a sulfonylurea or insulin. Signs: shakiness, sweating, confusion.
• Vision changes in diabetes. Tell the prescriber about any change in vision.

The two labels share the boxed warning. These are warnings, not forecasts. The prescriber decides what happens with the medicine if a sign appears.

What does the thyroid C-cell tumor boxed warning say?

The boxed warning on both labels says tirzepatide caused thyroid C-cell tumors in rats and that it is unknown whether it does so in humans. That is the substance of the warning on the Zepbound and Mounjaro labels, and the two are the same.

The wording has three parts. In rats, the tumors were dose-dependent and treatment-duration-dependent. In humans, the labels say it is unknown whether tirzepatide causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC). And the medicine is contraindicated for people with a personal or family history of MTC or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).

So the warning is a screening question, not a general alarm. Before prescribing, the prescriber asks about that specific history. The labels describe a finding in rats and state that its relevance to humans is unknown.

The Warnings and Precautions section on thyroid tumors asks people to report symptoms such as a lump or swelling in the neck, hoarseness, trouble swallowing or shortness of breath to their prescriber.

Do the Zepbound and Mounjaro label figures differ?

Yes, the figures differ between the Zepbound and Mounjaro labels, and the populations differ too. Zepbound's figures come from weight-management trials, and Mounjaro's come from trials in adults with type 2 diabetes.

Nausea shows the gap. Zepbound reports 25%, 29% and 28% on 5, 10 and 15 mg, and Mounjaro reports 12%, 15% and 18%. Placebo rates also differ: 8% against 4%. The same pattern holds for vomiting, where Zepbound's 15 mg figure is 13% and Mounjaro's is 9%.

Two cautions apply. The populations, comparator arms and durations are not the same, so the rows are not a head-to-head test. And the two labels carry the same boxed warning.

One difference matters in practice. Hypoglycemia is reported in diabetes populations, and the Mounjaro label gives blood glucose under 54 mg/dL with basal insulin at 13% on placebo and 16%, 19% and 14% on 5, 10 and 15 mg. The choice between products belongs to the reader and their prescriber, and this guide takes no side.

How do the EU label's frequency categories compare to the US percentages?

The EU product information for Mounjaro groups each reaction into a frequency category, and "very common" means 1 in 10 people or more, which is 10% or more. The categories are very common (at least 1/10), common (1/100 to under 1/10), uncommon (1/1,000 to under 1/100) and rare.

The Spanish Mounjaro ficha técnica from the AEMPS database gives these for the reactions above. In Spanish, the categories read "muy frecuentes", "frecuentes", "poco frecuentes" and "raras".

• Nausea, diarrhea, vomiting, constipation and abdominal pain: very common.
• Injection site reactions: common.
• Acute pancreatitis and cholelithiasis or cholecystitis: uncommon.
• Hypersensitivity: common. Anaphylaxis and angioedema: rare, from postmarketing data.
• Hypoglycemia with a sulfonylurea or insulin: very common. With metformin and SGLT2 inhibitors: common.

Some US figures sit inside their EU band. Mounjaro nausea of 12% to 18% is above 10%, so very common. The overall injection site rate of 3.2% sits between 1% and 10%, so common. Gallbladder disease at 0.6% sits between 0.1% and 1%, so uncommon.

Other rows do not map cleanly. Some US doses fall below 10% even where the EU category is very common, for example Mounjaro vomiting at 5% to 9% and constipation at 6% to 7%. The two documents report different data sets, so compare a category with a range, not with one dose's number.

Where do the label figures line up side by side?

The table below sets the Zepbound and Mounjaro label percentages beside the EU frequency category for each reaction, from the Zepbound and Mounjaro FDA labels and the EU product information. Each cell reads placebo, then 5, 10 and 15 mg.

To use it, find the row for your symptom, pick the column for your drug and read your dose against placebo. Mounjaro vomiting at 15 mg is 9% against 2% on placebo, an excess of 7 points. Zepbound vomiting at 15 mg is 13% against 2%, an excess of 11 points.

The table reports trial averages for the populations and doses studied. It does not predict what you will feel.

Which mistakes cost the most when reading side effect figures?

The costliest mistakes are merging the two labels, ignoring placebo and treating a trial average as a forecast. Each can send a reader away with a wrong picture of how common a symptom is.

• Keep the two labels apart. A Zepbound weight-trial percentage and a Mounjaro diabetes-trial percentage describe different people, so never average them. The fatigue rows in the guide to fatigue rates on four labels show how each label is read on its own.
• Read the placebo column first. Placebo groups report nausea too, 8% on Zepbound and 4% on Mounjaro, so the excess is the useful number.
• Match the dose step, not just the drug. Rates differ across 5, 10 and 15 mg, and the Zepbound label's own dose-escalation steps show the order the label uses.
• Treat averages as averages. A label rate describes a trial group, not one person, and how Mounjaro's effect and side effects build up over the first weeks on a dose explains the timeline on each dose.
• Leave dose decisions to the prescriber. A table never says whether to change a dose, and the Mounjaro half-life calculator gives an estimate of active medicine, not advice.

How can Dose & Lose help you track side effects?

Dose & Lose is a tracking app that lets you rate symptoms such as nausea and fatigue from 0 to 10, day by day, next to your logged doses. It does not prescribe or give dosing advice, and it does not measure anything in the body.

With the Dose & Lose app, you can log a side effect's severity against the dose date, along with the injection site and a pain level from 0 to 10. Over weeks, you can see your symptom ratings over time next to your doses.

A log cannot tell you whether a symptom is serious, and the warning signs above stand regardless of what the app shows.

Frequently asked questions

Do Zepbound and Mounjaro side effects get better over time?

Lilly's medical information page says gastrointestinal effects mostly occur during dose escalation and ease over time. The FDA label tables give rates by dose, not by week, so they show how common an effect is rather than how long it lasts. Persistent or worsening symptoms belong with the prescriber.

What percentage of people get nausea on Zepbound?

In the Zepbound label's pooled weight trials, nausea occurred in 25% of adults on 5 mg, 29% on 10 mg and 28% on 15 mg, against 8% on placebo. The SURMOUNT-1 trial, over 72 weeks, reported 24.6%, 33.3% and 31.0% against 9.5%. The label pools two studies, while SURMOUNT-1 is a single trial.

How long do Mounjaro side effects last?

The Mounjaro label reports how many people had each reaction, not how long it lasted, so it gives no duration. Lilly ties gastrointestinal effects mainly to dose escalation. For the build-up on each dose, see how long Mounjaro takes to work, and log your own symptoms against dose dates.

Does the thyroid cancer warning mean Zepbound or Mounjaro causes cancer in people?

No, the labels do not say that. The boxed warning describes thyroid C-cell tumors in rats and states it is unknown whether tirzepatide causes them in humans, including medullary thyroid carcinoma. It is a contraindication for a personal or family history of MTC or MEN 2, which the prescriber checks.

Is hypoglycemia a concern for everyone taking Mounjaro?

Not in every case. The EU text rates hypoglycemia as very common with a sulfonylurea or insulin and common with metformin and SGLT2 inhibitors. With basal insulin, the US label reports blood glucose under 54 mg/dL in 16%, 19% and 14% on 5, 10 and 15 mg, against 13% on placebo.

Sources

Every figure above comes from the records below. Published by Petros IT Solutions SRL under the byline Dose & Lose Editorial Team.

• Zepbound prescribing information (FDA label via DailyMed): adverse reaction percentages by dose, warnings and the boxed warning.
• Mounjaro prescribing information (FDA label via DailyMed): type 2 diabetes trial percentages, hypoglycemia and the boxed warning.
• SURMOUNT-1, New England Journal of Medicine: 72-week adverse event rates by dose.
• Mounjaro ficha técnica, AEMPS CIMA: EU frequency categories in section 4.8.
• Lilly medical information on Zepbound side effects: the manufacturer's note on gastrointestinal effects during dose escalation.

Corrections: office@doseandlose.com.