Understanding NDMA: What does NDMA do to your body?

October 9, 2025 •

5 min read

The U.S. Environmental Protection Agency (EPA) has classified N-nitrosodimethylamine (NDMA) as a probable human carcinogen, based on evidence from animal studies. It is a toxic chemical that has garnered significant public attention due to its detection as an impurity in several common medications, leaving many to wonder what NDMA does to your body.

Quick Summary

NDMA is a probable human carcinogen causing DNA-damaging metabolites in the liver. High exposure can cause acute liver toxicity, while long-term exposure may increase cancer risk. Exposure sources include cured meats, water, and past medication contamination.

Key Points

NDMA is a Probable Carcinogen: Based on extensive animal studies, NDMA is classified as a probable human carcinogen, primarily causing liver damage and increasing cancer risk.
Toxicity is Caused by a Metabolite: The NDMA molecule itself is not the main toxic agent; it is converted by liver enzymes into a reactive methyldiazonium ion that damages DNA.
Liver is the Primary Target: Because the liver metabolizes NDMA, it is the main organ affected, with acute exposure causing severe damage and chronic exposure leading to fibrosis, cirrhosis, and potential tumors.
Exposure Comes from Many Sources: NDMA exposure occurs through diet (e.g., cured meats), drinking water, tobacco smoke, and pharmaceutical products, though typically in very low amounts.
Pharmaceutical Contamination Led to Recalls: Recent NDMA contamination in blood pressure medication (valsartan) and antacids (ranitidine) resulted in major product recalls, prompting stricter manufacturing regulations.
Risk Mitigation is a Priority: Regulatory bodies and manufacturers are working to reduce NDMA levels by improving raw material testing, optimizing manufacturing processes, and implementing preventative measures.

What is NDMA and How Are We Exposed?

N-nitrosodimethylamine (NDMA) is a semi-volatile organic chemical that is formed through both natural processes and industrial activities. It is not intentionally produced for commercial sale in the United States, but it can be inadvertently generated from chemical reactions involving certain amines and nitrosating agents. While most people are exposed to NDMA at very low levels, its presence in some medications has raised significant public health concerns.

Common sources of NDMA exposure include:

Foods and beverages: Cured meats, processed fish, and malt beverages like beer and whiskey may contain low levels of NDMA. Cooking processes, particularly frying bacon, can also lead to NDMA formation.
Drinking water: NDMA can form as a byproduct of the water disinfection process, especially when chloramines are used. Levels are typically very low, but they can be a source of constant exposure.
Tobacco smoke: Both mainstream and secondhand smoke contain NDMA.
Industrial processes: Tanneries, tire manufacturers, and fish processing facilities are among the industries that may inadvertently produce and release NDMA.
Pharmaceuticals: NDMA contamination has been detected in a number of medications, leading to major recalls. The contamination can arise during manufacturing from contaminated raw materials or solvents, or from the degradation of the drug substance itself.

The Toxic Mechanism: How NDMA Causes Harm

The toxic effects of NDMA are not caused by the compound itself but by its metabolites, primarily formed in the liver. When NDMA is absorbed into the body, it is metabolized by a specific group of liver enzymes, predominantly Cytochrome P450 2E1 (CYP2E1). This metabolic process leads to the formation of a highly reactive intermediate called the methyldiazonium ion.

This methyldiazonium ion is an alkylating agent, meaning it can attach alkyl groups to macromolecules within the body. Its most dangerous action is the methylation of DNA, which forms DNA adducts. A specific and highly carcinogenic DNA adduct, O6-methylguanine, is a key driver of NDMA's carcinogenic potential. These DNA adducts can cause mutations, which can lead to uncontrolled cell growth and, eventually, cancer.

The Role of the Liver

The liver is the primary target organ for NDMA toxicity because it is the main site of NDMA metabolism. High-level exposure can lead to rapid and severe liver damage, including hemorrhagic necrosis, where liver cells die and bleed. Survivors of severe acute exposure may develop liver fibrosis or cirrhosis over the long term. Animal studies have consistently shown that NDMA causes liver damage and liver tumors.

Acute Versus Chronic Exposure

The health effects of NDMA depend heavily on the dose and duration of exposure. This is a critical distinction, especially when considering low-level contamination in pharmaceuticals versus accidental high-dose poisoning.

Acute (High-Dose) Exposure:

Symptoms: Nausea, vomiting, headaches, fever, jaundice, dizziness, and abdominal cramps.
Outcome: Severe, acute liver damage and hemorrhagic necrosis. Fatalities from high-dose NDMA poisoning have been reported.

Chronic (Low-Dose) Exposure:

Symptoms: Long-term exposure, even at low levels, may cause chronic liver damage and potentially low platelet counts.
Outcome: Increased risk of cancer, particularly liver, kidney, and lung tumors, based on extensive animal evidence. Some human epidemiological studies have also suggested links to gastric, colorectal, bladder, and prostate cancers.

NDMA in Medications: Recalls and Risks

Since 2018, the discovery of NDMA impurities in widely used medications, such as certain angiotensin II receptor blockers (e.g., valsartan), ranitidine (Zantac), and metformin, has triggered widespread recalls. Regulatory bodies like the FDA have established acceptable daily intake limits for nitrosamines in pharmaceuticals to minimize potential long-term cancer risks.

Comparison of NDMA Exposure Sources


Exposure Source	Typical NDMA Levels	Associated Risks	Regulatory Status
Pharmaceuticals	Varies widely, can exceed FDA limits (e.g., 96 ng/day)	Increased cancer risk with long-term use of contaminated products	FDA has set acceptable daily intake limits and issued recalls for affected drugs
Foods (e.g., cured meats)	Often in micrograms per kg (μg/kg) range, typically higher than water	Exposure considered minor compared to endogenous sources for most people; reduced significantly over time with processing changes	Generally considered a low-level, background exposure source
Drinking Water	Parts per trillion (ppt) range; typically very low	Very minor source of exposure compared to food and endogenous formation	Monitored by regulatory bodies like the EPA; NDMA levels are well below health advisory levels
Endogenous Formation	Varies based on diet (nitrites/amines)	Largest source for most people, but levels are influenced by dietary factors	Natural process, not regulated; can be influenced by diet (e.g., limiting nitrites)

Protecting Against NDMA Exposure

Regulators have responded to the issue of NDMA in medications by demanding that manufacturers identify and mitigate potential sources of contamination. This includes implementing stricter controls on raw materials, manufacturing processes, and storage conditions.

Strategies to reduce contamination include:

Better Raw Material Selection: Using high-purity raw materials and excipients (inactive ingredients) with low nitrite content.
Process Optimization: Modifying manufacturing steps, like controlling temperature and pH, to prevent NDMA formation.
Improved Testing: Using sensitive and specific analytical methods to detect even trace amounts of NDMA.
Antioxidants: Adding antioxidants like Vitamin C can inhibit nitrosamine formation.

For consumers, it is crucial to stay informed about recalls and regulatory updates. Patients taking recalled medications should consult their healthcare providers for safe alternatives but should not stop taking their medication without professional guidance. The FDA maintains an updated webpage on nitrosamine impurities in medications for public access.

Conclusion: Mitigating the Risks of NDMA

In summary, NDMA is a potent hepatotoxic agent and probable human carcinogen due to its metabolic activation into a DNA-damaging compound. While low-level exposure occurs through various sources like food and water, the primary concern arose from contamination found in certain pharmaceuticals, leading to widespread recalls. The potential for acute liver damage at high doses and increased cancer risk with chronic exposure are the main health concerns. In response, regulators like the FDA have implemented stringent measures for manufacturers, focusing on prevention, testing, and continuous monitoring to ensure drug safety. For patients, staying informed and following guidance from healthcare professionals is the safest path forward when concerns about NDMA in medications arise.

Frequently Asked Questions

NDMA, or N-nitrosodimethylamine, is a chemical that is classified as a probable human carcinogen by several international health agencies. It is toxic to the liver and has been found as an impurity in some foods, water, and medications.

NDMA was an unintended impurity in certain medications, resulting from specific manufacturing processes or the chemical degradation of the drug itself. In some cases, changes to manufacturing methods unintentionally created the right chemical conditions for NDMA to form.

High-level, acute exposure to NDMA can cause severe liver damage, leading to nausea, vomiting, fever, and jaundice. Long-term, low-level exposure is associated with an increased risk of cancer, particularly liver, lung, and kidney tumors.

There are tests that can detect NDMA or its metabolites in urine shortly after exposure. However, these tests cannot predict future health effects and NDMA is rapidly metabolized, so they are not useful for long-term risk assessment.

No, patients should not stop taking prescribed medication without first consulting their healthcare provider. The FDA recommends speaking with a doctor about potential concerns and safer treatment options, as discontinuing essential medication could pose greater health risks.

The FDA and other regulatory agencies have issued guidance requiring manufacturers to perform risk assessments, implement stricter quality controls on raw materials, optimize manufacturing processes (e.g., pH and temperature control), and use more sensitive analytical testing methods.

Besides pharmaceuticals, low levels of NDMA can be found in cured meats, smoked fish, malt beverages like beer, drinking water, and tobacco smoke. The body can also produce NDMA endogenously from precursor chemicals.