Who should not use Mounjaro and what options are available

Medications for obesity and diabetes have been widely researched and discussed, especially with the emergence of new drugs such as tirzepatide, marketed as Mounjaro (Eli Lilly). This medication was originally developed to control blood glucose levels in people with type 2 diabetes, but it has also shown significant weight-loss effects when combined with lifestyle changes. In Brazil, the National Health Surveillance Agency (ANVISA, 2025) has authorized its use for individuals with high body mass index (BMI) and obesity-related comorbidities.

However, not everyone is eligible to use this medication. Certain individuals should not use it under any circumstances, including those with a personal or family history of thyroid cancer or multiple endocrine neoplasia type 2 (MEN 2). These conditions increase the risk of thyroid tumors, as warned by the drug manufacturer (StatPearls, 2025). People with known allergies to tirzepatide are also contraindicated, since severe reactions such as swelling and anaphylaxis have been reported (StatPearls, 2025).

In addition, physicians are advised not to prescribe Mounjaro to patients with severe gastrointestinal disorders, such as gastroparesis, due to the lack of safety data in this population. Individuals with a history of pancreatitis should also avoid its use, as the drug affects gastric emptying and may worsen this condition (Eli Lilly, 2025). Some evidence suggests that patients with kidney disease or diabetic retinopathy may use the medication under strict monitoring, although potential complications require careful evaluation (Peptide Initiative, 2025).

Pregnant women or those planning pregnancy should not use tirzepatide, as its effects on fetal development are unknown. The same recommendation applies to breastfeeding women (Medx, 2025). Children and adolescents are also not eligible for treatment until further studies confirm safety and efficacy in these age groups (Gov Health Report, 2025).

Given these restrictions, alternative treatments must be considered. Medications such as Ozempic and Wegovy, which contain semaglutide, are approved for weight management in specific cases and have more established long-term safety profiles. Semaglutide may be a suitable option for individuals who cannot tolerate tirzepatide (Health.com, 2024). Liraglutide is another pharmacological alternative, depending on the patient’s clinical condition.

Beyond medication, lifestyle modification remains essential. Calorie-restricted diets and increased physical activity are the foundation of obesity treatment and metabolic health, ideally supported by a multidisciplinary healthcare team. Bariatric surgery may also be considered for patients with severe obesity who do not achieve adequate results with conservative or pharmacological approaches.

In summary, Mounjaro is an effective option for obesity and type 2 diabetes, but it is not appropriate for everyone. Individuals with thyroid cancer history, drug allergies, severe gastrointestinal disorders, pregnancy, or pediatric age should not use it. Medical evaluation is essential to determine whether alternative medications, lifestyle interventions, or surgical treatment are more appropriate for each case.

ANVISA. Mounjaro® (tirzepatida): nova indicação. Agência Nacional de Vigilância Sanitária, Brasília, 09 jun. 2025. Disponível em: https://www.gov.br/anvisa/pt-br/assuntos/medicamentos/novos-medicamentos-e-indicacoes/mounjaro-r-tirzepatida-nova-indicacao. Acesso em: 13 jan. 2026.

DRUGS.COM. Tirzepatide (Monograph). Drugs.com, 10 jul. 2025. Disponível em: https://www.drugs.com/monograph/tirzepatide.html. Acesso em: 13 jan. 2026.

ELI LILLY AND COMPANY. Open Letter Regarding the Use of Mounjaro® (tirzepatide) and Zepbound® (tirzepatide). 2025. Disponível em: https://lilly.gcs-web.com/news-releases/news-release-details/open-letter-regarding-use-of-mounjaror-tirzepatide-and-zepboundr. Acesso em: 13 jan. 2026.

GOV HEALTH REPORT. Who Should Not Take Mounjaro? Contraindications & Safety. 09 dez. 2025. Disponível em: https://www.govhealthreport.com/articles/who-should-not-take-mounjaro. Acesso em: 13 jan. 2026.

MEDX.IT.COM. What are the drawbacks of tirzepatide? Risks and side effects explained. 2025. Disponível em: https://medx.it.com/what-are-the-drawbacks-of-tirzepatide-an-overview-of-risks-side-effects-and-other-concerns. Acesso em: 13 jan. 2026.

STATPEARLS. Tirzepatide. NCBI Bookshelf, 2025. Disponível em: https://www.ncbi.nlm.nih.gov/sites/books/NBK585056/. Acesso em: 13 jan. 2026.

THE GUARDIAN. Mounjaro is second obesity drug to be approved for use in England. 04 jun. 2024. Disponível em: https://www.theguardian.com/society/article/2024/jun/04/mounjaro-is-second-obesity-drug-to-be-approved-for-use-in-england. Acesso em: 13 jan. 2026.