What We Know About the McDonald’s E. coli Outbreak
CDC and FDA traced 104 E. coli O157:H7 illnesses, 34 hospitalizations, 4 cases of hemolytic uremic syndrome (HUS), and 1 death in Colorado to slivered yellow onions served on McDonald’s Quarter Pounder sandwiches. Illnesses spanned 14 states with onset dates ranging from September 12 to October 21, 2024. CDC declared the outbreak over on December 3, 2024.
The Source: Taylor Farms Slivered Onions
Epidemiologic and traceback data pointed to fresh slivered yellow onions served on Quarter Pounders as the likely source, though the outbreak strain was never found in onion or environmental samples. The onions came from a single supplier, Taylor Farms. On October 22, 2024, Taylor Farms Colorado recalled 15,687 cases of sliced, diced, slivered, and ringed yellow onions for food service, along with smaller quantities of whole onions. FDA classified the recall as Class I, its most serious category, and ended it on February 11, 2025.
By the time CDC announced the outbreak on October 22, 2024, McDonald’s had already stopped using slivered onions and Quarter Pounder beef patties in affected states. FDA said stores in Colorado, Kansas, and Wyoming and in parts of Idaho, Iowa, Missouri, Montana, Nebraska, Nevada, New Mexico, Oklahoma, and Utah paused the onions, and McDonald’s later brought them back from a different supplier. USDA-FSIS reported that the evidence didn’t point to the beef patties. Within weeks, recalled onions had been removed from the supply chain and new illnesses stopped.
FDA inspected the Taylor Farms plant in Colorado Springs from October 28 to November 12, 2024. Inspectors observed equipment with apparent biofilm and food debris after cleaning, though these observations aren’t a final agency finding.
A Concentrated Mountain West Outbreak
Colorado had the most cases (30), followed by Montana (19), Nebraska (13), and New Mexico (10). Sick people lived in 14 states, but FDA listed 12 states for the recalled onions, and CDC said at least seven people ate at McDonald’s while traveling. The single reported death was an older adult in Colorado, and wasn’t one of the 4 HUS cases.
Ron Simon & Associates Filed the First Lawsuit Against McDonald’s
Ron Simon & Associates filed the nation’s first lawsuit against McDonald’s in the 2024 E. coli outbreak. Our attorneys represented customers who were hospitalized, children who developed HUS, and families affected by the death in Colorado. Lawsuits against McDonald’s and Taylor Farms have continued, including a new suit filed in Mesa County, Colorado, in August 2026.
Why HUS Cases Matter
E. coli O157:H7 produces Shiga toxin, which can damage the lining of blood vessels and kidneys. Children under 5 face the highest risk of developing HUS, a complication that can require dialysis, cause permanent kidney damage, and in severe cases be fatal. HUS typically develops 5 to 10 days after diarrhea starts. Warning signs include decreased urination, extreme fatigue, and unexplained bruising.
Your Legal Rights
If you or your child ate a McDonald’s Quarter Pounder at a McDonald’s that served the recalled onions between September and late October 2024 and developed laboratory-confirmed E. coli O157:H7 illness, your family may be entitled to compensation for medical expenses, hospitalization costs, lost income, pain and suffering, and other damages. A claim may also seek the cost of long hospital stays and years of follow-up care for HUS and kidney injury.
Ron Simon & Associates is a food poisoning law firm that has recovered over $850 million for victims nationwide. Our E. coli attorneys focus exclusively on foodborne illness litigation and continue to investigate claims from this outbreak. You pay our law firm nothing unless we recover compensation for you. Contact us for a free consultation at 1-888-335-4901.