ByHeart Botulism Outbreak jumps to 51 – Illnesses date from December 24, 2023 to December 1, 2025

States with illnesses: Arizona 5, California 12, Idaho 2, Illinois 2, Kentucky 1, Massachusetts 2, Maine 1, Michigan 1, Minnesota 3, North Carolina 2, New Jersey 1, Ohio 1, Oregon 4, Pennsylvania 1, Rhode Island 1, Texas 8, Virginia 1, Washington 2 and Wisconsin 1.

The FDA and CDC, in collaboration with the California Department of Public Health (CDPH), Infant Botulism Treatment and Prevention Program (IBTPP), and other state and local partners, continue to investigate a multistate outbreak of infant botulism. Epidemiologic and laboratory data show that ByHeart Whole Nutrition infant formula might be contaminated with Clostridium botulinum, which is causing infant illness in multiple regions of the country.

ByHeart’s and FDA’s investigations into the root cause of the outbreak are ongoing, and at this time, FDA cannot rule out the possibility that contamination might have affected all ByHeart formula products. In response, CDC broadened the case definition to include any infant with botulism who was exposed to ByHeart formula at any time since the product’s release in March 2022. As of December 10, 2025, a total of 51 infants with suspected or confirmed infant botulism and confirmed exposure to ByHeart Whole Nutrition infant formula (various lots) have been reported from 19 states.  

Previously, case counts included illnesses from August 1, 2025, onward. With the expanded definition, CDC and state partners identified 10 additional cases that occurred from December 2023 through July 2025. At this time, no cases have been identified between March 2022 and December 2023. All 10 are confirmed infant botulism cases with documented exposure to ByHeart formula.

Laboratory confirmation for some cases is ongoing. Illnesses started on dates ranging from December 24, 2023 to December 1, 2025. All 51 infants were hospitalized. No deaths have been reported to date. The infants range in age from 16 to 264 days and 22 (43%) are female.  

State and local public health officials are interviewing caregivers about the foods the infants were fed in the month before they got sick. Fifty-one infants have been identified that were fed ByHeart Whole Nutrition powdered infant formula before getting sick.

FDA has not received reports of recalled formula being found on store shelves since November 26, 2025.  All ByHeart infant formula products have been recalled, and these products should not be available for sale in stores or online. This includes all formula cans and single-serve “anywhere pack” sticks.

Additional testing by ByHeart, FDA, CDC, and state partners is underway, and results are expected in the coming weeks. Positive sample results for finished product testing will be included and updated in the Sample Results section.

FDA’s investigation is ongoing to determine the point of contamination. This advisory will be updated as information becomes available.  

Republished with permission from Bill Marler and Marler Clark. Copyright (c) Marler Clark LLP, PS. All rights reserved.