Mounjaro side effects
In Mounjaro's FDA label (revised Aug 27, 2026), the most common side effects at 15 mg were nausea (18% vs 4% on placebo), diarrhea (17% vs 9%) and decreased appetite (11% vs 1%).
Source: FDA label on DailyMed (Eli Lilly and Company), revised , version 40. Read every day: a new FDA version updates this page by itself.
How often Mounjaro side effects happened
Table 1: Adverse Reactions in Pool of Placebo-Controlled Trials Reported in ≥5% of MOUNJARO-treated Adult Patients with Type 2 Diabetes Mellitus
| Side effect | Mounjaro 15 mg | Placebo |
|---|---|---|
| Nausea | 18% | 4% |
| Diarrhea | 17% | 9% |
| Decreased appetite | 11% | 1% |
| Vomiting | 9% | 2% |
| Constipation | 7% | 1% |
| Abdominal pain | 5% | 4% |
| Indigestion | 5% | 3% |
People in the trial reporting each side effect, as FDA prints it. The placebo column is the rate among people given no medication, which is why a side effect can be common on both.
Boxed warning
- In both male and female rats, tirzepatide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures. It is unknown whether MOUNJARO causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans as human relevance of tirzepatide-induced rodent thyroid C-cell tumors has not been determined [see Warnings and Precautions (5.1) and Nonclinical Toxicology (13.1)].
- MOUNJARO is contraindicated in patients with a personal or family history of MTC or in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) [see Contraindications (4)] . Counsel patients regarding the potential risk for MTC with the use of MOUNJARO and inform them of symptoms of thyroid tumors (e.g., a mass in the neck, dysphagia, dyspnea, persistent hoarseness). Routine monitoring of serum calcitonin or using thyroid ultrasound is of uncertain value for early detection of MTC in patients treated with MOUNJARO [see Contraindications (4) and Warnings and Precautions (5.1)].
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
What the label warns about
Section 5 of the label, word for word.
Risk of Thyroid C-Cell Tumors
In both sexes of rats, tirzepatide caused a dose-dependent and treatment-duration-dependent increase in the incidence of thyroid C-cell tumors (adenomas and carcinomas) in a 2-year study at clinically relevant plasma exposures [see Nonclinical Toxicology (13.1)] . It is unknown whether MOUNJARO causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans as human relevance of tirzepatide-induced rodent thyroid C-cell tumors has not been determined.
MOUNJARO is contraindicated in patients with a personal or family history of MTC or in patients with MEN 2. Counsel patients regarding the potential risk for MTC with the use of MOUNJARO and inform them of symptoms of thyroid tumors (e.g., a mass in the neck, dysphagia, dyspnea, persistent hoarseness).
Routine monitoring of serum calcitonin or using thyroid ultrasound is of uncertain value for early detection of MTC in patients treated with MOUNJARO. Such monitoring may increase the risk of unnecessary procedures, due to the low test specificity for serum calcitonin and a high background incidence of thyroid disease. Significantly elevated serum calcitonin values may indicate MTC and patients with MTC usually have calcitonin values >50 ng/L. If serum calcitonin is measured and found to be elevated, the patient should be further evaluated. Patients with thyroid nodules noted on physical examination or neck imaging should also be further evaluated.
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
Acute Pancreatitis
Acute pancreatitis, including fatal and non-fatal hemorrhagic or necrotizing pancreatitis, has been observed in patients treated with GLP-1 receptor agonists, or MOUNJARO [see Adverse Reactions (6)] .
After initiation of MOUNJARO, observe patients carefully 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. If pancreatitis is suspected, discontinue MOUNJARO and initiate appropriate management.
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
Hypoglycemia with Concomitant Use of Insulin Secretagogues or Insulin
Patients receiving MOUNJARO in combination with an insulin secretagogue (e.g., sulfonylurea) or insulin may have an increased risk of hypoglycemia, including severe hypoglycemia [see Adverse Reactions (6.1), Drug Interactions (7.1)] .
The risk of hypoglycemia may be lowered by a reduction in the dose of sulfonylurea (or other concomitantly administered insulin secretagogue) or insulin. Inform patients using these concomitant medications of the risk of hypoglycemia and educate them on the signs and symptoms of hypoglycemia.
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
Hypersensitivity Reactions
Serious hypersensitivity reactions (e.g., anaphylaxis, angioedema) have been reported in patients treated with MOUNJARO. If hypersensitivity reactions occur, discontinue use of MOUNJARO; treat promptly per standard of care, and monitor until signs and symptoms resolve. Do not use in patients with a previous serious hypersensitivity reaction to tirzepatide or any of the excipients in MOUNJARO [see Contraindications (4), Adverse Reactions (6.2)] .
Anaphylaxis and angioedema have been reported with GLP-1 receptor agonists. Use caution in patients with a history of angioedema or anaphylaxis with a GLP-1 receptor agonist because it is unknown whether such patients will be predisposed to these reactions with MOUNJARO.
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
Acute Kidney Injury Due to Volume Depletion
There have been postmarketing reports of acute kidney injury, in some cases requiring hemodialysis, in patients treated with GLP-1 receptor agonists, or MOUNJARO. The majority of the reported events occurred in patients who experienced gastrointestinal adverse reactions leading to dehydration such as nausea, vomiting, or diarrhea [see Adverse Reactions (6)] .
Monitor renal function in patients reporting adverse reactions to MOUNJARO that could lead to volume depletion, especially during dosage initiation and escalation of MOUNJARO.
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
Severe Gastrointestinal Adverse Reactions
Use of MOUNJARO has been associated with gastrointestinal adverse reactions, sometimes severe [see Adverse Reactions (6)] . In the pool of placebo-controlled trials in adults, severe gastrointestinal adverse reactions occurred more frequently among patients receiving MOUNJARO (5 mg 1.3%, 10 mg 0.4%, 15 mg 1.2%) than placebo (0.9%). Severe gastrointestinal adverse reactions have also been reported postmarketing with GLP-1 receptor agonists.
MOUNJARO is not recommended in patients with severe gastroparesis.
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
Diabetic Retinopathy Complications in Patients with a History of Diabetic Retinopathy
Temporary worsening of diabetic retinopathy has been reported with rapid improvement in glucose control. Patients with a history of diabetic retinopathy should be monitored for progression of diabetic retinopathy.
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
Acute Gallbladder Disease
Acute events of gallbladder disease such as cholelithiasis or cholecystitis have been reported in GLP-1 receptor agonist trials and postmarketing.
In MOUNJARO placebo-controlled clinical trials in adults, acute gallbladder disease (cholelithiasis, biliary colic, and cholecystectomy) was reported by 0.6% of MOUNJARO-treated patients and 0% of placebo-treated patients. If cholelithiasis is suspected, gallbladder diagnostic studies and appropriate clinical follow-up are indicated.
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
Pulmonary Aspiration During General Anesthesia or Deep Sedation
MOUNJARO delays gastric emptying [see Clinical Pharmacology (12.2)] . There have been rare postmarketing reports of pulmonary aspiration in patients receiving GLP-1 receptor agonists undergoing elective surgeries or procedures requiring general anesthesia or deep sedation who had residual gastric contents despite reported adherence to preoperative fasting recommendations.
Available data are insufficient to inform recommendations to mitigate the risk of pulmonary aspiration during general anesthesia or deep sedation in patients taking MOUNJARO, including whether modifying preoperative fasting recommendations or temporarily discontinuing MOUNJARO could reduce the incidence of retained gastric contents. Instruct patients to inform healthcare providers prior to any planned surgeries or procedures if they are taking MOUNJARO.
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
Never Share a MOUNJARO KwikPen Between Patients
Never share MOUNJARO KwikPen between patients, even if the pen needle is changed. Sharing poses a risk for transmission of blood-borne pathogens.
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
Who should not take Mounjaro
MOUNJARO is contraindicated in patients with:
- A personal or family history of medullary thyroid carcinoma (MTC) or in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) [see Warnings and Precautions (5.1)] .
- Known serious hypersensitivity to tirzepatide or any of the excipients in MOUNJARO. Serious hypersensitivity reactions, including anaphylaxis and angioedema, have been reported with MOUNJARO [see Warnings and Precautions (5.4)] .
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
Mounjaro, pregnancy and breastfeeding
Pregnancy
Risk Summary
Available data with MOUNJARO use in pregnant women are insufficient to evaluate for a drug-related risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. There are risks to the mother and fetus associated with poorly controlled diabetes in pregnancy (see Clinical Considerations) . Based on animal reproduction studies, there may be risks to the fetus from exposure to tirzepatide during pregnancy. MOUNJARO should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
In pregnant rats administered tirzepatide during organogenesis, fetal growth reductions and fetal abnormalities occurred at clinical exposure in maternal rats based on AUC. In rabbits administered tirzepatide during organogenesis, fetal growth reductions were observed at clinically relevant exposures based on AUC. These adverse embryo/fetal effects in animals coincided with pharmacological effects on maternal weight and food consumption (see Data) .
The estimated background risk of major birth defects is 6–10% in women with pre-gestational diabetes with an HbA1c >7% and has been reported to be as high as 20–25% in women with an HbA1c >10%. The estimated background risk of miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2–4% and 15–20%, respectively.
Clinical Considerations
Disease-Associated Maternal and/or Embryo/Fetal Risk
Poorly controlled diabetes in pregnancy increases the maternal risk for diabetic ketoacidosis, pre-eclampsia, spontaneous abortions, preterm delivery, and delivery complications. Poorly controlled diabetes increases the fetal risk for major birth defects, stillbirth, and macrosomia-related morbidity.
Data
Animal Data
In pregnant rats given twice weekly subcutaneous doses of 0.02, 0.1, and 0.5 mg/kg tirzepatide (0.03-, 0.07-, and 0.5-fold the MRHD of 15 mg once weekly based on AUC) during organogenesis, increased incidences of external, visceral, and skeletal malformations, increased incidences of visceral and skeletal developmental variations, and decreased fetal weights coincided with pharmacologically-mediated reductions in maternal body weights and food consumption at 0.5 mg/kg. In pregnant rabbits given once weekly subcutaneous doses of 0.01, 0.03, or 0.1 mg/kg tirzepatide (0.01-, 0.06-, and 0.2-fold the MRHD) during organogenesis, pharmacologically-mediated effects on the gastrointestinal system resulting in maternal mortality or abortion in a few rabbits occurred at all dose levels. Reduced fetal weights associated with decreased maternal food consumption and body weights were observed at 0.1 mg/kg. In a pre- and post-natal study in rats administered subcutaneous doses of 0.02, 0.10, or 0.25 mg/kg tirzepatide twice weekly from implantation through lactation, F 1 pups from F 0 maternal rats given 0.25 mg/kg tirzepatide had statistically significant lower mean body weight when compared to controls from post-natal day 7 through post-natal day 126 for males and post-natal day 56 for females.
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
Breastfeeding
Risk Summary
In a single-dose clinical lactation study, the concentration of tirzepatide in breast milk was found to be either undetectable or low compared to the maternal administered dose ( see Data ). There are no available data on the effects of tirzepatide on the breastfed infant or on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for MOUNJARO and any potential adverse effects on the breastfed infant from MOUNJARO or from the underlying maternal condition.
Data
Following subcutaneous administration of a single 5 mg dose to 11 healthy lactating adult females, the concentration of tirzepatide in breast milk was found to be undetectable (limit of detection in breast milk 4 ng/mL) in 164/171 samples assayed. The cumulative amount of tirzepatide detected in the remaining 7 breast milk samples over the 28-day sampling window was equivalent to less than 0.02% of the maternal administered dose, with the last measurable concentrations occurring 5 days post-dose. The AUC of tirzepatide in breast milk could not be calculated, due to insufficient quantifiable concentrations.
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
What Mounjaro interacts with
Concomitant Use with an Insulin Secretagogue (e.g., Sulfonylurea) or with Insulin
When initiating MOUNJARO, consider reducing the dose of concomitantly administered insulin secretagogues (e.g., sulfonylureas) or insulin to reduce the risk of hypoglycemia [see Warnings and Precautions (5.3)].
Oral Medications
MOUNJARO delays gastric emptying and thereby has the potential to impact the absorption of concomitantly administered oral medications. Caution should be exercised when oral medications are concomitantly administered with MOUNJARO.
Monitor patients on oral medications dependent on threshold concentrations for efficacy and those with a narrow therapeutic index (e.g., warfarin) when concomitantly administered with MOUNJARO.
Advise patients using oral hormonal contraceptives to switch to a non-oral contraceptive method or add a barrier method of contraception for 4 weeks after initiation and for 4 weeks after each dose escalation with MOUNJARO. Hormonal contraceptives that are not administered orally should not be affected [see Use in Specific Populations (8.3) and Clinical Pharmacology (12.2, 12.3)].
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
All side-effect tables and trial data in the label
Everything the label reports under adverse reactions, in its own order.
The following serious adverse reactions are described below or elsewhere in the prescribing information:
- Risk of Thyroid C-cell Tumors [see Warnings and Precautions (5.1)]
- Acute Pancreatitis [see Warnings and Precautions (5.2)]
- Hypoglycemia with Concomitant Use of Insulin Secretagogues or Insulin [see Warnings and Precautions (5.3)]
- Hypersensitivity Reactions [see Warnings and Precautions (5.4)]
- Acute Kidney Injury Due to Volume Depletion [see Warnings and Precautions (5.5)]
- Severe Gastrointestinal Adverse Reactions [see Warnings and Precautions (5.6)]
- Diabetic Retinopathy Complications in Patients with a History of Diabetic Retinopathy [see Warnings and Precautions (5.7)]
- Acute Gallbladder Disease [see Warnings and Precautions (5.8)]
- Pulmonary Aspiration During General Anesthesia or Deep Sedation [see Warnings and Precautions (5.9)]
Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Adverse Reactions in the Clinical Trials of Adults with Type 2 Diabetes Mellitus
Pool of Two Placebo-Controlled Clinical Trials in Adults
The data in Table 1 are derived from 2 placebo-controlled trials [1 monotherapy trial (SURPASS-1) and 1 trial in combination with basal insulin with or without metformin (SURPASS-5)] in adult patients with type 2 diabetes mellitus [see Clinical Studies (14.2, 14.4)] . These data reflect exposure of 718 patients to MOUNJARO and a mean duration of exposure to MOUNJARO of 36.6 weeks. The mean age of patients was 58 years, 4% were 75 years or older and 54% were male. The population was 57% White, 27% Asian, 13% American Indian or Alaska Native, and 3% Black or African American; 25% identified as Hispanic or Latino ethnicity. At baseline, patients had type 2 diabetes mellitus for an average of 9.1 years with a mean HbA1c of 8.1%. As assessed by baseline fundoscopic examination, 13% of the population had retinopathy. At baseline, eGFR was ≥90 mL/min/1.73 m 2 in 53%, 60 to 90 mL/min/1.73 m 2 in 39%, 45 to 60 mL/min/1.73 m 2 in 7%, and 30 to 45 mL/min/1.73 m 2 in 1% of patients.
Pool of Seven Controlled Clinical Trials
Adverse reactions were also evaluated in a larger pool of adult patients with type 2 diabetes mellitus participating in seven controlled clinical trials which included two placebo-controlled trials (SURPASS-1 and -5), three trials of MOUNJARO in combination with metformin, sulfonylureas, and/or SGLT2 Inhibitors (SURPASS-2, -3, -4) [see Clinical Studies (14.3)] and two additional trials conducted in Japan. In this pool, a total of 5119 adult patients with type 2 diabetes mellitus were treated with MOUNJARO for a mean duration of 48.1 weeks. The mean age of patients was 58 years, 4% were 75 years or older and 58% were male. The population was 65% White, 24% Asian, 7% American Indian or Alaska Native, and 3% Black or African American; 38% identified as Hispanic or Latino ethnicity. At baseline, patients had type 2 diabetes mellitus for an average of 9.1 years with a mean HbA1c of 8.3%. As assessed by baseline fundoscopic examination, 15% of the population had retinopathy. At baseline, eGFR was ≥90 mL/min/1.73 m 2 in 52%, 60 to 90 mL/min/1.73 m 2 in 40%, 45 to 60 mL/min/1.73 m 2 in 6%, and 30 to 45 mL/min/1.73 m 2 in 1% of patients.
Common Adverse Reactions in Adults
Table 1 shows common adverse reactions, not including hypoglycemia, associated with the use of MOUNJARO in the pool of placebo-controlled trials in adults. These adverse reactions occurred more commonly on MOUNJARO than on placebo and occurred in at least 5% of patients treated with MOUNJARO.
| Adverse Reaction | Placebo (N=235) % | MOUNJARO 5 mg (N=237) % | MOUNJARO 10 mg (N=240) % | MOUNJARO 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 |
Note: Percentages reflect the number of patients who reported at least 1 occurrence of the adverse reaction.
In the pool of seven clinical trials in adults, the types and frequency of common adverse reactions, not including hypoglycemia, were similar to those listed in Table 1 .
In a CV outcomes trial of 6,647 adults with type 2 diabetes mellitus and established CV disease exposed to MOUNJARO, adverse reactions reported with MOUNJARO were similar with the exception of dysesthesia (0.7%), decreased appetite (17%), constipation (13%), vomiting (12%), abdominal pain (10%), and fatigue (10%) [see Clinical Studies (14.6)] .
Gastrointestinal Adverse Reactions
In the pool of placebo-controlled trials in adults, gastrointestinal adverse reactions occurred more frequently among patients receiving MOUNJARO than placebo (placebo 20.4%, MOUNJARO 5 mg 37.1%, MOUNJARO 10 mg 39.6%, MOUNJARO 15 mg 43.6%). More patients receiving MOUNJARO 5 mg (3.0%), MOUNJARO 10 mg (5.4%), and MOUNJARO 15 mg (6.6%) discontinued treatment due to gastrointestinal adverse reactions than patients receiving placebo (0.4%). The majority of reports of nausea, vomiting, and/or diarrhea occurred during dose escalation and decreased over time.
The following gastrointestinal adverse reactions were reported more frequently in MOUNJARO-treated adult patients than placebo-treated patients (frequencies listed, respectively, as: placebo; 5 mg; 10 mg; 15 mg): eructation (0.4%, 3.0%, 2.5%, 3.3%), flatulence (0%, 1.3%, 2.5%, 2.9%), gastroesophageal reflux disease (0.4%, 1.7%, 2.5%, 1.7%), abdominal distension (0.4%, 0.4%, 2.9%, 0.8%).
Adverse Reactions in the Clinical Trial of Pediatric Patients 10 Years of Age and Older with Type 2 Diabetes Mellitus
MOUNJARO was administered to 97 pediatric patients 10 years of age and older with type 2 diabetes mellitus for a mean duration of 39.9 weeks [see Clinical Studies (14.5)] . The mean age was 15 years and 61% of patients were female. The population was 58% White, 11% Black or African American, 6% Asian, 20% American Indian or Alaska Native, and 5% were other races; 66% identified as Hispanic or Latino ethnicity. At baseline, pediatric patients had type 2 diabetes mellitus for an average of 2.4 years with a mean HbA1c of 8.0%.
The incidences of adverse reactions reported in pediatric patients treated with MOUNJARO 5 mg and 10 mg subcutaneously once-weekly were consistent with those described above for adult patients with type 2 diabetes mellitus with the exception of a higher incidence of vomiting, abdominal pain, and hypoglycemia. During the 30-week placebo-controlled period of the study, vomiting occurred in 3%, 16%, and 12% of patients and abdominal pain occurred in 9%, 22%, and 15% of patients treated with placebo, MOUNJARO 5 mg, and 10 mg, respectively.
Other Adverse Reactions in Adults and Pediatric Patients 10 Years of Age and Older with Type 2 Diabetes Mellitus
Hypoglycemia
Adults with Type 2 Diabetes Mellitus
Table 2 summarizes the incidence of hypoglycemic events in the placebo-controlled trials in adults.
| Placebo % | MOUNJARO 5 mg % | MOUNJARO 10 mg % | MOUNJARO 15 mg % | |
| Monotherapy | ||||
| (40 weeks)* | N=115 | N=121 | N=119 | N=120 |
| Blood glucose <54 mg/dL | 1 | 0 | 0 | 0 |
| Severe hypoglycemia** | 0 | 0 | 0 | 0 |
| Add-on to Basal Insulin with or without Metformin | ||||
| (40 weeks)* | N=120 | N=116 | N=119 | N=120 |
| Blood glucose <54 mg/dL | 13 | 16 | 19 | 14 |
| Severe hypoglycemia** | 0 | 0 | 2 | 1 |
Note: Percentages reflect the number of patients who reported at least 1 episode of hypoglycemia in respective categories.
* Reflects the study treatment period. Data include events occurring during 4 weeks of treatment-free safety follow up. Events after introduction of a new glucose-lowering treatment are excluded.
** Episodes requiring the assistance of another person to actively administer carbohydrate, glucagon, or other resuscitative actions.
Hypoglycemia was more frequent when MOUNJARO was used in combination with a sulfonylurea [see Clinical Studies (14)] . In an adult clinical trial up to 104 weeks of treatment, when administered with a sulfonylurea, hypoglycemia (glucose level <54 mg/dL) occurred in 13.8%, 9.9%, and 12.8%, and severe hypoglycemia occurred in 0.5%, 0%, and 0.6% of patients treated with MOUNJARO 5 mg, 10 mg, and 15 mg, respectively.
Pediatric Patients 10 years of Age and Older with Type 2 Diabetes Mellitus
No severe hypoglycemia episodes were reported during the trial in pediatric patients 10 years of age and older with type 2 diabetes mellitus. Table 3 summarizes the incidence of hypoglycemic events with blood glucose <54 mg/dL in this trial.
| Placebo % | MOUNJARO 5 mg % | MOUNJARO 10 mg % | |
| Add on to basal insulin with or without metformin | N=10 | N=10 | N=11 |
| Blood glucose <54 mg/dL | 10 | 30 | 27 |
| Add on to metformin alone | N=24 | N=22 | N=22 |
| Blood glucose <54 mg/dL | 4 | 9 | 9 |
Note: Percentages reflect the number of patients who reported at least 1 episode of blood glucose <54 mg/dL.
a Events after the introduction of a new glucose-lowering treatment are excluded.
Acute Pancreatitis
In clinical studies, 14 events of acute pancreatitis were confirmed by adjudication in 13 MOUNJARO-treated adult patients (0.23 patients per 100 years of exposure) versus 3 events in 3 comparator-treated patients (0.11 patients per 100 years of exposure).
Heart Rate Increase
In the pool of placebo-controlled trials in adults, treatment with MOUNJARO resulted in a mean increase in heart rate of 2 to 4 beats per minute compared to a mean increase of 1 beat per minute in placebo-treated patients. Episodes of sinus tachycardia, associated with a concomitant increase from baseline in heart rate of ≥15 beats per minute, also were reported in 4.3%, 4.6%, 5.9% and 10% of subjects treated with placebo, MOUNJARO 5 mg, 10 mg, and 15 mg, respectively. For patients enrolled in Japan, these episodes were reported in 7% (3/43), 7.1% (3/42), 9.3% (4/43), and 23% (10/43) of patients treated with placebo, MOUNJARO 5 mg, 10 mg, and 15 mg, respectively. The clinical relevance of heart rate increases is uncertain.
Hypersensitivity Reactions
Hypersensitivity reactions have been reported with MOUNJARO in the pool of placebo-controlled trials in adults, sometimes severe (e.g., urticaria and eczema); hypersensitivity reactions were reported in 3.2% of MOUNJARO-treated patients compared to 1.7% of placebo-treated patients.
In the pool of seven clinical trials in adults , hypersensitivity reactions occurred in 106/2,570 (4.1%) of MOUNJARO-treated adult patients with anti-tirzepatide antibodies and in 73/2,455 (3.0%) of MOUNJARO-treated patients who did not develop anti-tirzepatide antibodies. In the clinical trial in pediatric patients 10 years of age and older, hypersensitivity reactions occurred in 2/50 (4%) of MOUNJARO-treated pediatric patients with anti-tirzepatide antibodies and in 0/43 (0%) of MOUNJARO-treated pediatric patients who did not develop anti-tirzepatide antibodies [see Clinical Pharmacology (12.6)].
Injection Site Reactions
In the pool of placebo-controlled trials in adults, injection site reactions were reported in 3.2% of MOUNJARO-treated patients compared to 0.4% of placebo-treated patients.
In the pool of seven clinical trials, injection site reactions occurred in 119/2,570 (4.6%) of MOUNJARO-treated adult patients with anti-tirzepatide antibodies and in 18/2,455 (0.7%) of MOUNJARO-treated adult patients who did not develop anti-tirzepatide antibodies. In the clinical trial in pediatric patients 10 years of age and older, injection site reactions occurred in 3/50 (6%) of MOUNJARO-treated pediatric patients with anti-tirzepatide antibodies and in 0/43 (0%) of MOUNJARO-treated pediatric patients who did not develop anti-tirzepatide antibodies [see Clinical Pharmacology (12.6)].
Acute Gallbladder Disease
In the pool of placebo-controlled clinical trials in adults, acute gallbladder disease (cholelithiasis, biliary colic and cholecystectomy) was reported by 0.6% of MOUNJARO-treated patients and 0% of placebo-treated patients.
Dysesthesia
In the pool of placebo-controlled clinical trials in adults, dysesthesia was reported by 0.4%, 0.4%, and 0.4% of patients treated with MOUNJARO 5 mg, 10 mg, and 15 mg, respectively. No events were reported by patients receiving placebo. In a CV outcomes trial, 0.7% of MOUNJARO-treated patients reported dysesthesia.
Dysgeusia
In the pool of placebo-controlled clinical trials in adults, dysgeusia was reported by 0.1% of MOUNJARO-treated patients and 0% of placebo-treated patients.
Laboratory Abnormalities
Amylase and Lipase Increase
In the pool of placebo-controlled clinical trials in adults, treatment with MOUNJARO resulted in mean increases from baseline in serum pancreatic amylase concentrations of 33% to 38% and serum lipase concentrations of 31% to 42%. Placebo-treated patients had a mean increase from baseline in pancreatic amylase of 4% and no changes were observed in lipase. The clinical significance of elevations in lipase or amylase with MOUNJARO is unknown in the absence of other signs and symptoms of pancreatitis.
In a CV outcomes trial, treatment with MOUNJARO resulted in mean increases from baseline in pancreatic amylase of 29% and lipase of 28%.
Postmarketing Experience
The following adverse reactions have been reported during post-approval use of MOUNJARO. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Hypersensitivity : anaphylaxis, angioedema
Gastrointestinal : acute pancreatitis, hemorrhagic and necrotizing pancreatitis sometimes resulting in death, ileus, intestinal obstruction, severe constipation including fecal impaction
Pulmonary : Pulmonary aspiration has occurred in patients receiving GLP-1 receptor agonists undergoing elective surgeries or procedures requiring general anesthesia or deep sedation
Renal : acute renal failure or worsening of chronic renal failure, sometimes requiring hemodialysis
Skin and Subcutaneous Tissue : alopecia
Source: Mounjaro prescribing information (FDA label on DailyMed), revised 2026-08-27
What changed for Tirzepatide
- RecallRecall: Tirzepatide/Niacinamide 2mL vial (40 MG per Vial) Inj 20mg/2mg/mL
- RecallRecall: TIRZEPATIDE/CYANOCOBALAMIN 26/2 MG/ML INJECTABLE, Packaged in single-use dosage…
- RecallRecall: TIRZEPATIDE 26 MG/ML INJECTABLE, Packaged in single-use dosage syringes, total mL…
- RecallRecall: Tirzepatide Injection, 18mg/mL, 4 mL Sterile Multi-Dose Vial
- RecallRecall: TIRZEPATIDE/CYANOCOBALAMIN 85/2 MG/ML INJECTABLE, Packaged in single-use dosage…
- RecallRecall: TIRZEPATIDE/CYANOCOBALAMIN 76/2 MG/ML INJECTABLE, Packaged in single-use dosage…
Written from each source's own record as it changes. Every change on GLPcompare
What people have reported to FDA about Mounjaro
97,440 reports name Mounjaro, 25,360 of them marked serious, in FDA's file of Oct 28, 2026. Anyone can file a report and a report names every medicine the person took, so these counts cannot show that Mounjaro caused a problem or how often it happens. For how often, use the trial rates above.
Symptoms reported most
- Nausea9,837
- Injection site pain9,482
- Diarrhea6,099
- Vomiting5,179
- Constipation3,769
- Bleeding at the injection site3,632
- Redness at the injection site3,184
- Blood glucose increased3,066
- Fatigue2,597
- Decreased appetite2,403
- Upper abdominal pain2,221
- Injection site bruising2,172
Pen, dose and use problems reported most
- Incorrect dose administered17,407
- Off label use8,153
- Extra dose administered5,249
- Product dose omission issue3,435
- Drug ineffective2,642
- Accidental underdose2,001
- Accidental overdose1,397
- Inappropriate schedule of product administration1,360
- Product administered at inappropriate site836
- Injury associated with device778
- Wrong technique in product usage process726
Counted through openFDA from FDA's Adverse Event Reporting System. One report can list several problems.
Mounjaro side effects: common questions
What are the most common side effects of Mounjaro?
In Mounjaro's FDA label (revised Aug 27, 2026), the most common side effects at 15 mg were nausea (18% vs 4% on placebo), diarrhea (17% vs 9%) and decreased appetite (11% vs 1%). These come from FDA's table of placebo-controlled trials (Table 1: Adverse Reactions in Pool of Placebo-Controlled Trials Reported in ≥5% of MOUNJARO-treated Adult Patients with Type 2 Diabetes Mellitus).
Does Mounjaro cause constipation?
In its FDA label, 7% of people taking Mounjaro at 15 mg reported constipation, against 1% on placebo.
Does Mounjaro cause hair loss?
Its FDA label lists alopecia among side effects reported after approval, without a rate: reports like these come from people using it in practice, so they cannot say how often it happens or prove the medicine caused it.
What serious side effects does the Mounjaro label warn about?
Its Warnings and Precautions section covers Risk of Thyroid C-Cell Tumors; Acute Pancreatitis; Hypoglycemia with Concomitant Use of Insulin Secretagogues or Insulin; Hypersensitivity Reactions; Acute Kidney Injury Due to Volume Depletion; Severe Gastrointestinal Adverse Reactions; Diabetic Retinopathy Complications in Patients with a History of Diabetic Retinopathy; Acute Gallbladder Disease; Pulmonary Aspiration During General Anesthesia or Deep Sedation; and Never Share a MOUNJARO KwikPen Between Patients.
Does Mounjaro have a boxed warning?
Yes. In both male and female rats, tirzepatide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures. It is unknown whether MOUNJARO causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans as human relevance of tirzepatide-induced rodent thyroid C-cell tumors has not been determined [see Warnings and Precautions (5.1) and Nonclinical...
Can you take Mounjaro while pregnant?
Available data with MOUNJARO use in pregnant women are insufficient to evaluate for a drug-related risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes.
Can you take Mounjaro while breastfeeding?
In a single-dose clinical lactation study, the concentration of tirzepatide in breast milk was found to be either undetectable or low compared to the maternal administered dose ( see Data ).
Should you stop Mounjaro before surgery?
Available data are insufficient to inform recommendations to mitigate the risk of pulmonary aspiration during general anesthesia or deep sedation in patients taking MOUNJARO, including whether modifying preoperative fasting recommendations or temporarily discontinuing MOUNJARO could reduce the incidence of retained gastric contents.
Does Mounjaro cause withdrawal symptoms?
The warnings and side effect sections of its FDA label do not list any. What trials do show after people stop a GLP-1 is weight coming back. What happens when you stop a GLP-1
Who should not take Mounjaro?
MOUNJARO is contraindicated in patients with: A personal or family history of medullary thyroid carcinoma (MTC) or in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Known serious hypersensitivity to tirzepatide or any of the excipients in MOUNJARO. Serious hypersensitivity reactions, including anaphylaxis and angioedema, have been reported with MOUNJARO.
How many side effect reports has FDA received about Mounjaro?
FDA's adverse event system holds 97,440 reports that name Mounjaro, 25,360 of them marked serious. The most reported symptoms are nausea, injection site pain, diarrhea. Anyone can file a report and a report names every medicine the person took, so these cannot show that Mounjaro caused a problem or how often it happens. The trial rates in its label do that.
Trial rates describe groups, not what one person will feel. Talk to your clinician before starting, stopping or changing a medicine. Label revised Aug 27, 2026.