Most common side effects in the label
The label’s table comes from two placebo-controlled trials in adults with type 2 diabetes (SURPASS-1 and SURPASS-5) and shows reactions by at least 5% of people taking Mounjaro® and more often than on placebo [1].
In the placebo-controlled pool, digestive side effects were reported by 37.1–43.6% on Mounjaro® depending on the dose vs 20.4% on placebo. Most nausea, vomiting and diarrhea reports came during dose escalation and decreased over time, and 3.0–6.6% stopped because of them vs 0.4% on placebo [1].
| Adverse reaction | Placebo (N=235) % | 5 mg (N=237) % | 10 mg (N=240) % | 15 mg (N=241) % |
|---|---|---|---|---|
| Nausea | 4 | 12 | 15 | 18 |
| Diarrhea | 9 | 12 | 13 | 17 |
| Decreased appetite | 1 | 5 | 10 | 11 |
| Vomiting | 2 | 5 | 5 | 9 |
| Constipation | 1 | 6 | 6 | 7 |
| Dyspepsia | 3 | 8 | 8 | 5 |
| Abdominal pain | 4 | 6 | 5 | 5 |
A reaction makes it into the label table only when at least 5% of people taking the medicine reported it and placebo users reported it less often; the placebo column shows how often the same complaint was reported without the medicine. The label also says these rates cannot be compared directly with other medicines’ trials [1]. The European Union product information (SmPC and package leaflet) is published by EMA [2]; local leaflets can differ in detail.
Serious side effects the label warns about
Mounjaro® carries a boxed warning: in rodents, the active ingredient caused thyroid C-cell tumors, and it is not known whether this happens in humans. The label rules it out for anyone who has had medullary thyroid carcinoma (MTC), or whose close family has, and for people with MEN 2 (a hereditary endocrine tumour syndrome). Section 6 of the label lists these serious adverse reactions [1]:
- Risk of thyroid C-cell tumors (the boxed warning)
- Acute pancreatitis
- Low blood sugar (hypoglycemia), with a higher risk alongside insulin or sulfonylurea-type medicines
- Hypersensitivity (allergic) reactions
- Acute kidney injury due to fluid loss (volume depletion)
- Severe gastrointestinal adverse reactions
- Diabetic retinopathy complications (eye problems related to diabetes)
- Acute gallbladder disease
- Food or liquid entering the lungs (pulmonary aspiration) under general anesthesia or deep sedation
What happens if I stop Mounjaro®?
The label does not describe how side effects change after stopping [1].
In SURMOUNT-4, people who had taken tirzepatide for 36 weeks were randomly switched to placebo or kept on treatment: over the next 52 weeks, weight changed by +14.0% on placebo vs −5.5% on continued tirzepatide [8]. That trial studied weight management, not type 2 diabetes.
Stopping, pausing or restarting is a decision to make with your prescriber.
Mounjaro®, pregnancy and birth control
Because Mounjaro® slows stomach emptying, it can make a birth-control pill work less well; the label says this effect is strongest after the first dose. For that reason it covers two windows, the first 4 weeks of treatment and the 4 weeks that follow every step up in dose: during each, it suggests either moving to a contraceptive that is not swallowed or using a barrier method on top of the pill. Patches, rings, injections and other non-oral hormonal methods are not expected to be affected [1]. It is not known whether Mounjaro® harms an unborn baby [1].
Plans for pregnancy or breastfeeding are worth raising with your prescriber before they happen.
Should I mention Mounjaro® before surgery or sedation?
Yes, according to the label. It describes rare postmarketing reports of food or liquid getting into the lungs (pulmonary aspiration) under general anesthesia or deep sedation in people taking GLP-1 receptor agonists, even when they had followed fasting instructions. The label says the data are not enough to recommend whether to change fasting or pause the medicine, and asks patients to tell their healthcare providers before any planned surgery or procedure [1].
Can I drink alcohol while taking Mounjaro®?
The Mounjaro® label does not mention drinking alcohol [1]. Two related facts come from general medical sources: heavy alcohol use is one of the most common causes of pancreatitis [3], which the label lists as a serious risk [1]; and drinking too much alcohol without enough food can cause low blood sugar in people with diabetes [4]. How alcohol fits with your treatment is a question for your prescriber.
Is hair loss listed for Mounjaro®?
Hair loss is not in the Mounjaro® clinical-trial tables. “Alopecia” (hair loss) appears in the label’s postmarketing section, which lists reports from a population of uncertain size, so neither how often it happens nor whether the medicine caused it can be reliably established [1].
For background, MedlinePlus describes a usually temporary kind of shedding (telogen effluvium) that can follow major physical stress, illness, surgery or crash diets [7]. A dermatologist or your prescriber can look at the cause.
Is burping listed for Mounjaro®?
The label lists belching (eructation) among digestive reactions reported more often than on placebo: 2.5–3.3% on Mounjaro® vs 0.4% on placebo [1]. It does not describe the smell, so “sulfur burps” as such are not a label term; if burping comes with heartburn, vomiting or stomach pain that will not go away, the table below says who to contact.
Mounjaro® is a trademark of Eli Lilly and Company. PepLabo is not affiliated with this company. This page is not medical advice; percentages come from clinical-trial tables in the label and do not predict what you will experience.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| Swelling of the lips, tongue, face or throat, struggling to breathe or swallow, fainting or a racing pulse | Emergency services. According to the guide, Mounjaro® should be stopped and urgent medical help sought. | Emergency | Mounjaro® Medication Guide [1]; MedlinePlus [6] |
| Belly pain that is severe and does not ease, whether or not you vomit; it can reach through to the back | Your healthcare provider right away; the guide says to stop using Mounjaro®. If you cannot reach them, urgent care. | Emergency | Mounjaro® Medication Guide [1]; NIDDK [3] |
| Ongoing nausea, vomiting or diarrhea, or dehydration signs such as feeling very thirsty, a dry mouth, urinating less than usual, dark urine or dizziness | Your healthcare provider, right away: fluid loss can lead to kidney problems. | Today | Mounjaro® Medication Guide [1]; MedlinePlus [5] |
| Pain in the upper stomach, fever, yellowing of the skin or eyes, or clay-colored stools | Your healthcare provider (gallbladder problems). | Today | Mounjaro® Medication Guide [1] |
| Shakiness, sweating, confusion, blurred vision or a fast heartbeat; the risk is higher alongside insulin or a sulfonylurea | Follow the low-blood-sugar plan from your healthcare provider; the guide asks you to discuss it before starting. | Today | Mounjaro® Medication Guide [1]; MedlinePlus [4] |
| A new neck lump or swelling, a hoarse voice, difficulty swallowing or breathlessness | Your healthcare provider (thyroid section of the guide). | Today | Mounjaro® Medication Guide [1] |
| Changes in vision during treatment | Your healthcare provider. | Today | Mounjaro® Medication Guide [1] |
| A planned surgery or a procedure with anesthesia or deep sedation | Tell every healthcare provider involved that you use this medicine, before the procedure. | At your next appointment | Mounjaro® Medication Guide [1] |
| Mild nausea, constipation, heartburn or other common side effects that you can manage | Mention them at your next appointment; a dated log helps. | At your next appointment | Common reactions: label section 6 [1] |
