Share on Pinterest
If you are taking metformin, you can talk to your physician about your medication. Getty Images
  • NDMA is a cancer-causing contaminant called N-Nitrosodimethylamine.
  • The FDA has been investigating the presence of NDMA in metformin drugs in the U.S. market since late 2010 after multiple batches of the diabetes drug sold outside the U.S. were found to contain low levels of the substance.
  • If you currently take metformin, it’s crucial to talk to your doctor about other treatment options.

The Food and Drug Administration (FDA) has announced that several lots of extended-release metformin — a popular type 2 diabetes drug — contain high levels of a cancer-causing contaminant called N-Nitrosodimethylamine (NDMA).

The organization stated it found high levels of the potentially harmful substance in the extended-release formulation of metformin and is asking multiple drug manufacturers to voluntarily recall the product.

Since the FDA’s announcement, two of the manufacturers contacted — Amneal Pharmaceuticals and Apotex Corp — have recalled extended-release 500-milligram and 750-milligram metformin tablets.

The FDA is also asking all manufacturers to test the metformin batches before distributing them.

The FDA has been investigating the presence of NDMA in metformin drugs in the U.S. market since late 2010 after multiple batches of the diabetes drug sold outside the United States were found to contain low levels of the substance.

NDMA was also detected in multiple other prescription and over-the-counter (OTC) medications, including ranitidine and certain blood pressure drugs, earlier this year. The drugs have since been recalled.

The overall risk of developing cancer from medications contaminated with small amounts of NDMA is low. However, if you currently take metformin, it’s crucial to talk to your doctor about other treatment options.

“While hearing that our medicines — agents essential for our health and well-being — could be compromised in any way is certainly alarming, it is important to understand the magnitude of the risk, which is extremely low,” Dr. Amir Masoud, a Yale Medicine gastroenterologist and assistant professor of internal medicine, told Healthline.

NDMA is classified as a probable human carcinogen, meaning it could potentially cause cancer.

We’ve all been exposed to low levels of the substance. NDMA has been detected in meat, vegetables, dairy products, soil, air, and water.

NDMA is all around us, Masoud explained.

The acceptable intake limit for NDMA in medications is 96 nanograms a day.

“The FDA does not expect to cause harm at levels below this cutoff. The risk of cancer is increased if people are exposed to it at higher levels at prolonged periods of time,” says Dr. Guy Mintz, the director of cardiovascular health & lipidology at Northwell Health’s Sandra Atlas Bass Heart Hospital in New York.

In high doses, NDMA may cause liver, lung, and kidney problems, according to studies conducted on animals. The World Health Organization (WHO) says it can also lead to gastric or colorectal cancer.

“NDMA has been shown to increase the incidence of cancer in animals as well as cause liver fibrosis and tumors in rats,” says Mintz.

No human cancer cases have been directly linked to NDMA at this time.

It’s not entirely clear how NDMA gets into medications.

According to the U.S. Environmental Protection Agency (EPA), NDMA forms during natural and industrial processes involving chemical reactions.

NDMA may form during the drug’s manufacturing process or when they are packaged and stored, the FDA stated. Our bodies may also produce NDMA as a byproduct when digesting certain food and drugs.

“It appears that a perfect storm of sorts has to take place: The compounds that form NDMA may be present in the drug and, under certain conditions, may form after formulation of the drug,” says Masoud.

The recall includes the extended-release formulations of metformin, not the immediate-release variety.

The FDA says patients who take extended-release metformin tablets shouldn’t stop taking the medication abruptly.

According to Mintz, doing so could negatively impact blood sugar levels and potentially lead to hospitalizations for hyperglycemia and ketoacidosis.

There is no short-term risk in continuing to take the medication until you talk to your doctor about other options.

“Immediately stopping any medication without the direct supervision and direction of your clinician is never the right answer,” Masoud said.

Mintz said there are many alternative options, including short-acting versions of metformin and other types of diabetes medications — SGLT2 inhibitors and GLP1 medications.

Your doctor will likely carefully change your treatment plan to mitigate any health risks.

“It’s essential to understand that independently stopping or changing your medications without input from your doctor can lead to direct and immediate risks far outweighing those posed by the possible contaminants discussed here,” Masoud said.

The Food and Drug Administration (FDA) has announced that several lots of metformin — a popular type 2 diabetes drug — contain high levels of a cancer-causing contaminant called N-Nitrosodimethylamine (NDMA).

The FDA has asked multiple drug manufacturers to voluntarily recall the medication and test any new batches before releasing them to the U.S. market.

Health experts warn that abruptly stopping the medication could have negative health consequences. There’s no short-term risk, so stick with it until you talk to your doctor about alternative treatment options.