Is the Roundup Herbicide Diquat Toxic?

According to a new review of more than 100 studies suggests diquat, an herbicide now used in Roundup products, could cause direct damage the intestines and could trigger a toxic chain reaction in the rest of the body, possibly increasing health risks.

As more research surfaces about the potential hazards of diquat exposure, including risks of neurological injury and other long-term health effects, the possibility of litigation is real. Farmers and homeowners have the right to seek accountability from manufacturers if it is proven that companies failed to warn about the dangers of their products.

Health Risks Linked to Diquat Exposure: Is the New Roundup Formula Even More Toxic?

Diquat, which has replaced glyphosate in Bayer’s Roundup herbicides, is banned in the European Union. The herbicide has been studied for years and has such global restrictions due to potential toxic effects on the liver and kidneys.

‍A published study in May 2025 in Frontiers in Pharmacology, suggests the chemical may harm the intestines as well. Researchers conclude that diquat may weaken the intestinal barrier, kill off beneficial bacteria, interfere with nutrient absorption, and trigger chronic inflammation. Studies suggest that diquat’s harmful impact on the intestine can extend to other organs, and this all adds to the case against the new Roundup formula safety profile.

In their report, the researchers wrote, “Studies show that Diquat primarily enters the body through the digestive tract, leading to poisoning. The core mechanism of its toxicity involves reactive oxygen species (ROS)-induced oxidative stress, which not only directly damages the intestinal barrier function but also exacerbates inflammation and systemic toxicity by disrupting the balance of the gut microbiota and the normal production of metabolic products.”

What Is Diquat?

Diquat (diquat dibromide) is a chemical herbicide used for aquatic weed control and general vegetation management. It works by producing reactive oxygen species in plants, destroying cell membranes and quickly kills vegetation. Due to its effectiveness, diquat has been used around the world since the 1950s. Common brand names containing diquat include:

• Reglone
• Reward
• Diquash

Diquat is banned in the EU and the U.K. due to both environmental and potential human health risks. It was ultimately banned because of the risks it poses to residents and passersby near the fields where it was sprayed, not to mention those who actually work closely with the herbicides in the fields. Even if a farmworker is wearing personal protective equipment (PPE), the European Food Safety Agency concluded in a report that worker exposure would exceed the maximum acceptable level by more than 4,000 percent.

Lessons From Roundup Litigation

The Roundup lawsuits offer a legal path for how litigation around diquat could develop. In those cases, thousands of plaintiffs alleged that exposure to glyphosate caused cancer, and that Monsanto (later acquired by Bayer) knew of the risks but failed to warn consumers.

If future lawsuits establish a link between diquat exposure and neurological conditions like Parkinson’s disease, a similar wave of litigation could emerge.

Who Is Most at Risk?

Those most likely to suffer health effects from diquat exposure include agricultural workers applying diquat on large-scale farms as well as groundskeepers and landscapers. Homeowners using the products could be exposed to a lesser degree, and so could families living near farms treated with diquat.

FAQs About Diquat and Potential Lawsuits

• Is diquat banned in the United States? Diquat is still legal for agricultural and residential use in the U.S., though the EPA classifies it as a highly toxic substance. Some countries and regulators have restricted its use due to safety concerns, which could influence future U.S. policy.

• What health problems are linked to diquat exposure? Studies suggest diquat exposure may contribute to neurological disorders such as Parkinson’s disease, respiratory damage, kidney and liver toxicity, eye injuries, and skin burns. Severe cases of ingestion have been fatal.

• How does diquat compare to Roundup (glyphosate)? Roundup has been linked primarily to non-Hodgkin lymphoma, whereas diquat is more often associated with neurological and organ damage. Both herbicides raise legal questions about whether manufacturers adequately warned users of the risks.

• Who is most at risk from diquat? Farmworkers, groundskeepers, landscapers, and homeowners who handle diquat without protective equipment face the highest risk. Families living near areas where diquat is heavily applied may also experience secondary exposure.

• Can I file a lawsuit if I developed Parkinson’s after using diquat? If you can demonstrate long-term exposure to diquat and later developed Parkinson’s disease or similar neurological conditions, you may be eligible to file a product liability or toxic exposure lawsuit. An attorney can help connect your medical history with product use.

Joe Lyon and his team of toxic exposure lawyers are investigating cancers and other serious illnesses linked to occupational toxic exposure.

We have filed numerous occupational cancer cases and settled many Roundup cancer claims on behalf of plaintiffs nationwide. Contact our attorneys for a free consultation and to seek compensation for the loss of health and financial damages.