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Is there a Cancer-Causing Ingredient in Metformin? FDA Investigation Results

By Eliza Skoler and Jimmy McDermott

The FDA finds that metformin does not contain dangerous amounts of a cancer-causing chemical called NDMA

Editor’s note: This article was updated on February 10, 2020.

The FDA investigated whether metformin contains a carcinogenic (cancer-causing) chemical called N-nitrosodimethylamine (NDMA). The FDA announced that laboratory results found that FDA-approved metformin products do not contain dangerous levels of NDMA.

Throughout the investigation, the agency recommended that people continue to take metformin. In a statement, FDA leader Dr. Janet Woodcock, said:

“Patients should continue taking metformin to keep their diabetes under control. It could be dangerous for patients with this serious condition to stop taking their metformin without first talking to their health care professional. The FDA recommends prescribers continue to use metformin when clinically appropriate, as the FDA investigation is still ongoing, and there are no alternative medications that treat this condition in the same way.”

Outside of the United States, some metformin medications have been found to contain clinically insignificant amounts of NDMA but have nevertheless been recalled. The FDA has not recommended metformin recalls in the United States.

Metformin is a medication used to lower blood glucose for people with type 2 diabetes, and it is one of the most common prescription medications in the United States. Historically, metformin has been the first medication given to many people with type 2 diabetes, and it is also sometimes prescribed for prediabetes, although it is not FDA-approved for prediabetes. Metformin is considered a safe, cheap, and effective medication worldwide, and is widely accessible in most countries. Read diaTribe's in-depth piece about metformin here.


1. Do you currently take metformin?

If so, don’t stop taking your medication. If you are concerned about the safety of the medication, please talk to your healthcare team. If they are not aware of the recent controversy, please take them a copy of this article.

2. What is NDMA?

NDMA is a chemical that is regularly found in small amounts in food and drinking water. This means that everyone is exposed to NDMA, but according to the FDA, low doses are not harmful to human health.

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