What are the health risks of taking Mounjaro

The short version: the evidence here shows tirzepatide is linked to a lower risk of blood clots in the lungs and legs, but a higher rate of gut side effects, especially early in treatment.

The 2026 TriNetX study, which compared about 117,000 tirzepatide users to matched people on lifestyle intervention alone, found the drug group had roughly one-quarter the risk of pulmonary embolism (0.18% vs 0.82%) and one-third the risk of deep vein thrombosis (0.33% vs 1.09%) over a year [1]. These are large, consistent reductions, but the study is observational and relied on diagnostic codes rather than confirmed imaging [1]. The funding source is not stated in the record, so the conflict picture is incomplete.

The gut side effects are the main known risk. A 2026 analysis of the FDA's FAERS database found tirzepatide was reported with gastrointestinal adverse events at about 2.8 times the rate of other drugs [2]. Most of these events started within the first three months, with a median onset of just 16 days [2]. Nausea, diarrhea, and vomiting were the most common, and the rates were similar to semaglutide in head-to-head trials [3]. People taking tirzepatide for diabetes had higher odds of gut side effects than those using it for weight loss alone [2].

The cardiovascular safety data from the SURPASS 4 trial showed no increase in heart attacks, strokes, or cardiovascular death compared to insulin glargine, though the confidence interval was wide [3]. The dedicated cardiovascular outcome trial was still ongoing at the time of that review [3].

My call: tirzepatide carries a real but manageable risk of early gastrointestinal side effects, while the evidence suggests a possible protective effect against blood clots that needs confirmation in trials with hard endpoints. Confidence: moderate for the gut side effects (consistent across multiple data sources), low for the clot protection (single observational study, no adjudicated outcomes).