Does Monjaro Cause Thrombosis?
Based on the available evidence, there is no established link between tirzepatide (Mounjaro) and thrombosis, though a single case report suggests a potential association that requires further investigation.
Current Evidence on Mounjaro and Thrombosis
The evidence regarding tirzepatide (Mounjaro) and thrombosis is extremely limited:
A recent case report describes a woman in her early 40s who developed pulmonary embolism approximately 20 days after starting tirzepatide, with no other identifiable risk factors for venous thromboembolism (VTE) 1. This is reported as the first such case worldwide.
The official literature and clinical trials on tirzepatide (SURPASS trials) do not list thrombosis or VTE as a common or established side effect 2.
Context of Thrombosis Risk in Related Conditions
Several factors are worth considering when evaluating this potential risk:
Patients with diabetes generally have an increased baseline risk of thrombotic events due to the prothrombotic state associated with the disease.
Obesity, which is often present in patients prescribed tirzepatide, is an independent risk factor for VTE.
Weight loss medications and significant rapid weight loss can sometimes alter coagulation parameters, though this mechanism has not been specifically established for tirzepatide.
Comparison with Other Medication Classes
Unlike some other medications that have established thrombotic risks:
Erythropoiesis-stimulating agents have a documented 67% increased risk of thromboembolic events compared to placebo (RR 1.67; 95% CI: 1.35–2.06) 3.
Multiple myeloma patients on thalidomide or lenalidomide have recognized thrombotic risks requiring prophylaxis 3.
Clinical Implications
For healthcare providers considering tirzepatide:
Routine thromboprophylaxis is not currently indicated for patients starting tirzepatide based on available evidence.
The European Myeloma Network specifically states that "although the risk of venous thromboembolism in MGUS is increased, the absolute risk is low. Therefore, there is no indication for standard thrombosis prophylaxis" 3. This principle of not providing prophylaxis for low absolute risks likely applies to tirzepatide as well.
Clinicians should maintain vigilance for symptoms of thrombosis (chest pain, shortness of breath, leg swelling or pain) in patients taking tirzepatide, particularly in those with other risk factors for thrombosis.
If thrombosis occurs in a patient on tirzepatide, consider the medication as a potential contributing factor, especially in the absence of other risk factors.
Conclusion
While a single case report suggests a possible association between tirzepatide and pulmonary embolism 1, there is insufficient evidence to establish causality or determine risk. More research is needed to clarify whether tirzepatide increases thrombosis risk and through what mechanisms. Clinicians should be aware of this potential but rare adverse effect while awaiting more definitive data.