Tirzepatide Has Fewer Overall Side Effects Than Liraglutide and Shows Unexpected Anti-Cancer and Anti-Inflammatory Benefits | Research

The takeaway

In a network meta-analysis of 19 RCTs and 13,529 patients, tirzepatide showed superior safety profiles for neoplasms and respiratory infections compared to both semaglutide and liraglutide, though it carried higher risk of severe hypoglycemia and injection-site reactions.

OR 5.15
Tirzepatide showed 5-fold lower odds of neoplasms compared to liraglutide — a surprising potential anti-cancer signal

What the researchers found

Key safety comparisons from the network meta-analysis:

- Liraglutide 3.0mg had significantly higher overall adverse events (OR 1.53-2.00) versus both semaglutide and tirzepatide

- Tirzepatide showed higher severe hypoglycemia risk (<54 mg/dL) and more injection-site reactions

- Tirzepatide demonstrated superior safety for neoplasms vs liraglutide (OR 5.15, 95% CI 1.28-20.74) and vs semaglutide (OR 3.55, 95% CI 1.10-11.54)

- Tirzepatide also showed fewer respiratory infections/nasopharyngitis

- GLP-1 monoagonists had fewer diarrhea events but more abdominal pain/dyspepsia

- Non-T2DM patients had significantly more adverse events than T2DM patients (P<0.05)

- No significant differences by race, BMI, or treatment duration

Why it matters

As prescriptions for weight loss peptide drugs surge, understanding their comparative safety is essential for clinical decision-making. This is the first large network meta-analysis to systematically compare tirzepatide against GLP-1 monoagonists for safety in obesity. The surprising finding that dual GIP/GLP-1 agonism may confer anti-neoplasm and anti-inflammatory benefits beyond what GLP-1 alone provides could shift how clinicians think about drug selection — particularly for patients with cancer risk factors or inflammatory conditions.

How the study worked

PRISMA-compliant systematic review registered in PROSPERO (CRD42024576314). Literature was searched in PubMed, Embase, and Cochrane through August 20, 2024. Included RCTs enrolled adults with BMI ≥27 (≥25 for Asians) receiving tirzepatide 10/15mg, semaglutide 2.4mg, or liraglutide 3.0mg. Network meta-analysis used odds ratios with 95% CIs, conducted in Stata 16.1. Subgroup, sensitivity, and funnel plot analyses were performed.

What this study cannot tell us

The neoplasm finding, while statistically significant, is based on a relatively small number of events and should be considered hypothesis-generating rather than definitive. The review includes only RCTs up to August 2024, so the most recent real-world data is not captured. Network meta-analysis compares drugs indirectly across trials with different populations and designs. The severe hypoglycemia finding for tirzepatide may partly reflect its stronger glucose-lowering effect. Follow-up durations in the included trials may be too short to capture long-term safety signals.

How to read the evidence

This is a PRISMA-compliant systematic review with network meta-analysis of 19 RCTs — high-quality evidence synthesis. The methodology includes sensitivity analyses and publication bias assessment, strengthening the findings.

When this study was published

Published in 2025 with literature through August 2024, this captures the most recent RCT data available for these incretin-based drugs in obesity.

The bigger picture

This analysis adds an important safety dimension to the ongoing comparison between single and dual incretin receptor agonists. While tirzepatide's superior efficacy for weight loss and glucose control is well-established, the finding of potential anti-neoplasm effects is novel and hypothesis-generating. If confirmed in dedicated studies, the GIP receptor component of tirzepatide may contribute protective effects beyond metabolic benefits, potentially influencing drug choice for patients with both obesity and cancer risk.

Questions still open

What is the biological mechanism behind tirzepatide's apparent anti-neoplasm effect — is it GIP-mediated or related to greater weight loss?
Should cancer risk history influence the choice between GLP-1 monoagonists and GIP/GLP-1 co-agonists?
Why do non-diabetic patients experience more adverse events than T2DM patients on these drugs?

Common questions

Which weight loss drug has the fewest side effects overall?

According to this analysis, semaglutide 2.4mg and tirzepatide 10/15mg had fewer overall adverse events than liraglutide 3.0mg. However, each drug has distinct side effect patterns: tirzepatide had more severe low blood sugar episodes and injection-site reactions, while GLP-1 monoagonists had more stomach pain. The 'safest' choice depends on a patient's individual risk factors.

Does tirzepatide really prevent cancer?

The study found significantly fewer neoplasm (tumor) events with tirzepatide compared to both semaglutide and liraglutide, which is an intriguing signal. However, this is based on a relatively small number of cancer events in weight loss trials that weren't designed to study cancer outcomes. It's an important finding that deserves further investigation, but it's too early to claim tirzepatide prevents cancer. The effect might be related to the GIP receptor component or simply greater weight loss.

Read the original research

Comparative Safety of GLP-1/GIP Co-Agonists Versus GLP-1 Receptor Agonists for Weight Loss in Patients with Obesity or Overweight: A Systematic Review.

Diabetes, metabolic syndrome and obesity : targets and therapy, 18, 2837-2849

View on PubMed ↗Publisher’s paper ↗

Citation

Xie, Zeyu; Liang, Zhuoru; Xie, Yilin; Zheng, Guimei; Cao, Weiling. (2025). Comparative Safety of GLP-1/GIP Co-Agonists Versus GLP-1 Receptor Agonists for Weight Loss in Patients with Obesity or Overweight: A Systematic Review.. Diabetes, metabolic syndrome and obesity : targets and therapy, 18, 2837-2849. https://doi.org/10.2147/DMSO.S537229