In an update released on January 23, the U.S. Food and Drug Administration (FDA) shared information about a contaminated ingredient in the multistate outbreak of infant botulism associated with ByHeart powdered infant formula. FDA is collaborating on the outbreak with the Centers for Disease Control and Prevention (CDC) and the California Department of Public Health's Infant Botulism Treatment and Prevention Program (IBTPP).

As of January 23, 2026, two samples collected by FDA have tested positive for Clostridium botulinum toxin Type A. One sample came from a closed canister of ByHeart powdered infant formula and matches a clinical isolate from an infant included in the outbreak, according to whole genome sequencing (WGS) analysis. 

The product samples also match two isolates found in samples of organic whole milk powder, an ingredient that ByHeart uses in the production of ByHeart Whole Nutrition powdered infant formula. The organic milk powder samples were collected and tested by ByHeart.

Other organic whole milk powder samples were collected by FDA at a processor for a supplier to ByHeart, and were analyzed by the New York Wadsworth Laboratory. WGS analysis showed that the Clostridium botulinum found in the sample of whole milk powder is a genetic match to the Clostridium botulinum detected in the finished product sample of ByHeart powdered infant formula. The name of the milk powder ingredient manufacturer was not released.

While these results help advance FDA's understanding of the outbreak, the investigation is ongoing to determine the source of contamination. FDA has established a webpage, FDA’s Actions to Respond to Clostridium botulinum Illnesses Associated with Consumption of Powdered Infant Formula, to capture ongoing efforts to ensure the safety of powdered infant formula, including general information about formula safety.

Outbreak History

As of December 2025, epidemiologic and laboratory analyses have confirmed that ByHeart Whole Nutrition infant formula contaminated with Clostridium botulinum is responsible for at least 51 instances of infant botulism across 19 states, with onset of illnesses going back as far as 2023. No new illness cases have been announced since December 10, 2025, and no deaths have been associated with this outbreak, although all 51 infants were hospitalized.

Previously, on December 23, 2025, ByHeart publicly reported positive test results for Clostridium botulinum in six of 36 samples of finished product. The six samples were taken from two batches (Batch 251261P2 and Batch 251131P2), which were both included in the initial product recall.

Since the outbreak came to light, ByHeart has come under increasing scrutiny for a history of food safety failures. FDA inspections found mold, dead insects, and leaking roof issues at its Reading, Pennsylvania facility (now closed), as well as rodent activity, rusty surfaces, and Cronobacter sakazakii-positive environmental swabs at the company’s Fullerton, Iowa plant.

FDA’s investigation of the outbreak is ongoing, and its outbreak investigation advisory will be updated as more information becomes available.