FDA Recalls Common Blood Pressure Drug Over Cancer-Causing Chemicals

A generic blood pressure medicine called prazosin, supplied by Teva Pharmaceuticals, is being recalled by the Food and Drug Administration (FDA) after tests found raised levels of cancer-causing chemicals known as nitrosamines.

Teva announced the recall on 7 Oct 2025, and it covers more than 580,000 prazosin capsules. Around 510,000 patients are prescribed prazosin each year. It is used for post-traumatic stress disorder as well as high blood pressure.

I am a pharmacologist and pharmacist who has researched nitrosamine contamination in widely used medicines for blood pressure, diabetes and heartburn, along with other challenges in generic drug manufacturing.

Prazosin has been sold as a generic for more than 25 years and, like many long-established generics, it is now made by several manufacturers.

That increased competition pushes prices down, which may help explain why older generics can be more vulnerable to manufacturing problems that could affect patient health.

Nitrosamines: what they are and how they arise

Nitrosamines are created as side-products in many everyday chemical reactions. They can form when a chemical unit called a nitrite group reacts with another called an amine group.

Certain industrial activities - including the production of rocket fuel, rubber and sealants - can generate high nitrosamine levels during processing. Foods such as bacon, pepperoni and salami contain nitrite preservatives; these can react with the meats’ amine groups to produce small quantities of nitrosamines.

A further source is the reaction that can occur when chlorinated water comes into contact with naturally occurring chemicals containing nitrogen and oxygen, again producing small amounts of nitrosamines.

Small, occasional exposure to nitrosamines is not generally considered dangerous. However, some research has shown that particular nitrosamines can be carcinogenic when consumed in high amounts over extended periods.

In 2018, European regulators were the first to identify that prescription medicines could be affected, after testing found a nitrosamine contaminant in an active ingredient used in the blood pressure medicine valsartan.

Because the Chinese company producing that active ingredient supplied multiple manufacturers of valsartan tablets, many firms - including Teva Pharmaceuticals - recalled the medicine at that time.

In response, the FDA began a large-scale programme to detect nitrosamines in prescription and over-the-counter medicines and to set thresholds for unsafe levels in tablets and capsules. It issued initial industry guidance in 2021, followed by an updated version in 2024.

Using the agency’s newer testing expectations, manufacturers have since identified nitrosamine contamination in commonly used medicines for blood pressure, diabetes, heartburn, infections (antibiotics) and smoking cessation. In most cases, the contamination occurred during chemical processing at a manufacturing facility.

What to do if you take Teva Pharmaceuticals prazosin

Teva Pharmaceuticals’ prazosin is only one of many generic versions - but it is the only one reported to be contaminated. You can check whether your medicine was supplied by Teva by looking at your prescription label. Look for the abbreviations MFG or MFR, which mean "manufacturing" or "manufacturer." If your label says "MFG Teva" or "MFR Teva," that indicates Teva Pharmaceuticals provided the medicine.

The manufacturer or distributor can also be identified from the National Drug Code, shown as NDC on the prescription label: the first four digits indicate the company. Teva products use 0093.

If Teva Pharmaceuticals is listed as the distributor, a pharmacist can use your prescription number to confirm the lot number and then match it against the lot numbers posted on the FDA website for recalled prazosin. If your lot is included, your pharmacy may be able to supply a different generic prazosin that is not part of this recall.

After assessing the risk for these tablets, the FDA classified the recall as Class II, meaning the medicine could cause "temporary or medically reversible adverse health consequences."

If your pharmacy does not have another prazosin option, do not stop taking the medicine without first speaking to your doctor. The short-term risk of taking tablets with increased nitrosamines may be lower than the risk associated with abruptly discontinuing this treatment.

Your doctor may also consider an alternative therapy, such as clonidine or trazodone.

Do older overseas-made generics carry greater risk?

Until recently, comparing safety records for generic medicines made overseas with the same generics produced in the United States was not feasible, because the FDA does not reveal which manufacturing plants companies use to produce tablets and capsules. However, in a 2025 study, researchers were able to infer that information by triangulating it from an FDA dataset.

They reported that the risk of serious adverse events was 54.3% higher for generics manufactured in India compared with those made in the United States. They also found that the longer a medicine has been available as a generic, the larger the safety-risk gap between its United States-made and India-made versions.

As my colleague and I noted in a commentary published alongside the study, the results imply that when multiple manufacturers crowd the generic market, lower-priced products tend to sell more strongly. Consequently, manufacturers in developing countries may be more likely to supply lower-quality medicines that cost less to produce.

Teva Pharmaceuticals operates manufacturing sites worldwide, including in India. The company has not stated where the recalled prazosin capsules - or their active and inactive ingredients - were manufactured.

The FDA publishes quality ratings for generic medicines and says that generics with an "A" rating satisfy the same manufacturing quality standards and achieve the same blood concentrations as branded medicines. However, pharmacies cannot use those ratings to determine whether a product comes from sites with a higher likelihood of quality problems.

Patients are largely dependent on the decisions pharmacies make about which generic versions they purchase for their shelves. In my view, if pharmacies had access to trustworthy quality information, they could make procurement choices that are safer for American consumers.

C. Michael White, Distinguished Professor of Pharmacy Practice, University of Connecticut

This article is republished from The Conversation under a Creative Commons licence. Read the original article.