GLP‑1 Medications and Thyroid Cancer: What the Latest Research Tells Us

As GLP‑1 medications like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) grow in popularity for weight loss and diabetes management, questions about long-term safety—particularly around thyroid cancer—have become more common.

So what does the latest research actually say?

Large Studies Offer Reassurance

Two recent, large-scale studies provide strong evidence that GLP‑1s are not associated with an increased risk of thyroid cancer in the general population:

International Multi-Country Study

A multinational study involving nearly 100,000 GLP‑1 users from Canada, Denmark, Norway, South Korea, Sweden, and Taiwan found no increased risk of thyroid cancer compared to users of another diabetes medication class (DPP-4 inhibitors).

• • Follow-up period: 1.8 to 3 years

  • Conclusion: Thyroid cancer incidence was not elevated in GLP‑1 users

  • Study link

U.S. OptumLabs Study

Another large study in the U.S. analyzed health data from more than 350,000 adults with type 2 diabetes. Again, researchers found:

• • Thyroid cancer rates were low overall

  • No significant difference in risk between GLP‑1 users and other medication users

  • Study link

What About the Slight Uptick in Year One?

Interestingly, the U.S. study did find a slightly higher rate of thyroid cancer diagnosis in the first year of GLP‑1 use (HR ~1.85). However, researchers believe this is most likely due to detection bias—not the medication itself. This means that clinicians are LOOKING for cancer more, thus FINDING more, however it’s not actually more— just earlier detection. And, that’s not necessarily a bad thing!

Here’s why:
Patients starting GLP‑1 therapy are often newly engaged in their health journey, meaning they’re more likely to receive bloodwork, imaging, and preventive screenings—such as thyroid ultrasounds. This can lead to increased identification of small, slow-growing thyroid nodules that might have otherwise gone unnoticed.

In other words: more testing = more findings, not more disease.

What This Means for Patients

The current data is overwhelmingly reassuring. Here’s what we know:

• Short-term GLP‑1 use appears safe: Large, diverse studies show no meaningful increase in thyroid cancer risk.

• Early detection bump is likely due to increased health monitoring—not the medication itself.

• No evidence of long-term harm has been found, but ongoing research will continue to clarify risks over time.

• GLP‑1s should still be avoided in patients with:

  • Personal or family history of medullary thyroid carcinoma (MTC)

  • Multiple endocrine neoplasia syndrome type 2 (MEN2)

Bottom Line

GLP‑1 medications remain a safe and effective tool for weight loss and metabolic health when prescribed appropriately. While ongoing studies will further define long-term safety, current research supports no causal link between GLP‑1 therapy and thyroid cancer in the general population.

Your provider should always review your individual risk factors, but for most people, the benefits far outweigh the concerns.

Schedule your free consultation with a provider in the Pacific Northwest here: Schedule Online

Find other helpful GLP-one (GLP-1) medication here: 

• What is the Best GLP One? Your Ultimate Guide to Weight Loss
• What Happens If You Stop GLP-1 medication? (Real Patient Stories)
• Can GLP-1s Prevent Alzheimers?

Disclaimer: This blog post is for informational purposes only and should not be considered medical advice. Always consult with a healthcare provider for personalized medical advice. GLP-1 medications must be obtained by prescription from a licensed health care provider.