Nitrosamines in Medications: What They Are and Why Recalls Keep Happening

• Contaminants, Not Ingredients: Nitrosamines are common chemicals which can increase cancer risk if you are exposed to high levels for a long time. They are not intentionally added to drugs but form accidentally during manufacturing or storage.
• Formation Pathway: They primarily form when an amine (a basic chemical group in many drugs) reacts with a source of nitrite, often due to impure raw materials or recycled solvents.
• Recalls Since 2018: The issue gained global attention in 2018 with the recall of the blood pressure drug Valsartan and has since led to recalls of other drugs, including Prazosin, Accuretic, and some diabetes medications.
• Risk Level: The risk from taking an affected pill is generally very low, as recalls are issued only when impurity levels exceed the FDA's strict safety limits for lifetime exposure.

In October 2025, more than half a million bottles of the blood pressure drug prazosin were pulled from shelves after tests revealed nitrosamine impurities. It wasn’t the first time, and likely won’t be the last.

Over the past few years, these hidden chemicals have triggered multiple drug recalls, raising questions about medication safety. So, what exactly are nitrosamines, how do they end up in your medicine, and what does this mean for you? Let’s break it down.

What Are Nitrosamines?

Nitrosamines are chemical compounds that form when certain ingredients mix under the wrong conditions. They are not rare. They form naturally at low levels in our food and water.

Where nitrosamines show up

Nitrosamines can form in certain foods when preservatives and proteins react during processing or cooking. They are found in cured meats like bacon, grilled meats, certain dairy products, beer, and some vegetables.

They can also be present at low levels in drinking water and in the air. We are exposed to these chemicals every day through our diet and environment. The World Health Organization says most people get small doses daily without realizing it

Why they are dangerous

The concern with nitrosamines is long term, not immediate. Several nitrosamines are classified as “probable human carcinogens,” meaning long-term exposure above safe limits could raise cancer risk.

Regulators set very conservative “acceptable intake” limits, amounts considered safe to take every day for life without increasing cancer risk.

Nitrosamines in Drugs

Because medicines are expected to meet very high quality standards, even low levels in drugs are taken seriously and must be controlled.

When nitrosamines are found above safety limits in a medicine, companies and regulators act out of caution, even if the actual risk is still considered low. This is why you may see recalls or safety notices, especially when the affected drugs are taken daily for months or years.

From First Discovery to Recent Recalls: The Nitrosamine Story

The nitrosamine issue first surfaced in 2018, when regulators detected an impurity called NDMA in certain lots of the blood pressure drug valsartan. This was a shock; valsartan had been trusted for years, so finding a potential carcinogen triggered a global investigation.

As experts dug deeper, they realized this wasn’t a one-off problem. Nitrosamines could form under several conditions: during chemical reactions in manufacturing, from contaminated or recycled solvents, from poorly cleaned equipment, or even through third-party suppliers reusing materials without strict controls.

That discovery set off a wave of reviews across the pharmaceutical industry. And soon, more recalls followed:

• March 2022: Pfizer recalled certain lots of Accuretic and its generics (quinapril/hydrochlorothiazide) after detecting nitrosamine levels above its internal limit. Patients were advised to consult their healthcare providers for alternatives.
• January 2023: Merck’s diabetes drugs Januvia and Janumet were found to contain small amounts of nitrosamines. Because these medications are critical for blood sugar control, patients were urged to speak with their prescribers before making any changes.
• October 2025: Over half a million bottles of the blood pressure drug prazosin were recalled for the same reason, proving the issue is still very much on the radar.

How Do Nitrosamines Sneak Into Medications?

Nitrosamines aren't added on purpose. They form by accident during making or storage.

• Chemical reactions during production: If an amine (a common chemical) meets nitrite in an acidic environment, a nitrosamine can form.
• Contaminated raw materials or recycled solvents: If these carry traces of nitrosamines, they can introduce impurities into the process.
• Poor cleaning between batches: Leftover residues can react during later steps.
• Third-party suppliers: Reused materials without proper controls can lead to contamination.

What the FDA Is Doing to Fix It

Since 2018, the FDA stepped up. They issued guides for manufacturers to spot and stop nitrosamines.

Key steps: Review full processes from raw materials to final packaging. Test if risks show up. Set daily intake limits to keep exposure safe.

Manufacturers must now:

• Boost quality checks
• Skip contamination-prone materials
• Verify clean recycled solvents
• Clean gear between batches
• Update methods for new risks

If impurities appear, companies fix the cause, recall if needed, and share data. It's a proactive shift to keep meds pure.

What This Means for You

Do not stop taking your medication without talking to your healthcare provider.

Finding nitrosamines doesn't make a drug instantly unsafe. The risk is very low. The FDA have established strict acceptable daily intake (AI) limits for nitrosamines. These limits are set so that taking a drug every day for 70 years at or below that limit is not expected to increase your risk of cancer.

Drug recalls happen when the detected levels exceed this safe limit. The risk is associated with long-term exposure to high levels, not necessarily short-term use.

The FDA assesses each case and gives advice. For critical meds, they might say continue while fixes happen.

If your drug gets recalled, check FDA alerts. Talk to your pharmacist or doctor; they'll guide safe alternatives. Stay informed, but don't panic; systems are improving to catch this early.