Health officials have dramatically expanded the scope of an outbreak of infant botulism linked to ByHeart Whole Nutrition Infant Formula, with the FDA now warning that all ByHeart formula ever produced since 2022 could have been contaminated with the botulism bacteria.
Previously, the outbreak case counts only included babies who got botulism after August 1, 2025. Now, health officials say it is possible that babies have been getting sick for years.
The FDA said it “cannot rule out the possibility” that all ByHeart formula products ever produced could have been contaminated with the botulism bacteria Clostridium botulinum.
ByHeart formula has been sold in the U.S. since March 2022, when it became the first new formula to be registered with the FDA in over 15 years. Less than a year later, ByHeart issued its first recall in December 2022 due to concerns about possible contamination with Cronobacter bacteria.
In the current outbreak, another 10 cases of infant botulism were identified after the CDC broadened the case definition to include any infant who was diagnosed with botulism after consuming ByHeart formula at any time since it hit the market in March 2022.
The outbreak now involves at least 51 babies in 19 states who got sick. The earliest illness was reported in December 2023 and the most recent illness was reported on December 1, 2025, according to the CDC Outbreak Investigation.
ByHeart recalled all of its formula products nationwide on November 11 and there have been no reports of it being found in stores since November 25, 2025, according to the FDA.
However, because it can take up to 30 days for infants to develop symptoms of botulism, the case count might still continue to grow.
Botulism can be deadly, but luckily all babies in this outbreak survived after they were hospitalized and treated with the botulism antitoxin.
Parents and caregivers of infants who consumed ByHeart Whole Nutrition Infant Formula should remain vigilant for symptoms, and seek immediate medical attention if the symptoms develop.
“Infant botulism often starts with constipation but is usually first noticed as difficulty feeding (sucking and swallowing), a weak and altered cry, and lack of head control,” according to the CDC.
Source: Outbreak Investigation of Infant Botulism: Infant Formula (November 2025)