Key points
- This outbreak is over, but activities to determine the root cause of C. botulinum in ByHeart powdered infant formula continue.
- The outbreak included 28 confirmed cases and 20 probable cases.
- No new cases have been added since December 2025, and 3 previously reported cases of suspected infant botulism from 3 states have been excluded.
- All ByHeart Whole Nutrition infant formula products have been recalled. If you have any ByHeart formula, do not use it and throw it away.
Investigation details
CDC, public health and regulatory officials in several states, the Infant Botulism Treatment and Prevention Program (IBTPP), and the U.S. Food and Drug Administration (FDA) collected different types of data to investigate a multistate outbreak of infant botulism. Infant botulism happens when a baby swallows Clostridium botulinum spores that grow in the gut and make toxin.
Epidemiologic and laboratory data showed that ByHeart Whole Nutrition infant formula was contaminated with C. botulinum and made infants sick. ByHeart recalled all of its infant formula on November 11, 2025.
Epidemiologic data
No new cases were added to the investigation since the update on December 10, 2025.
During recent weeks, public health officials reviewed the medical records of the 51 infants who were initially included in the investigation and used additional criteria to describe the cases. This led to the exclusion of 3 infants initially suspected to have infant botulism who were ultimately diagnosed with other illnesses.
The final case data for this investigation, as of February 26, 2026, are listed below.
Final case data
28
All 48 infants were hospitalized and treated with BabyBIG®, a medication used to treat infant botulism.
16 – 264 days
22 (46%) female
Criteria used to classify cases
- Consumed ByHeart Whole Nutrition infant formula
- Illness that started on or after March 23, 2022
- Laboratory test positive for C. botulinum or botulinum toxin
- Consumed ByHeart Whole Nutrition infant formula
- Illness that started on or after March 23, 2022
- Negative or inconclusive laboratory test results
- Signs, symptoms, and recovery compatible with infant botulism
- No alternate diagnosis from healthcare provider
- Consumed ByHeart Whole Nutrition infant formula
- Illness that started on or after March 23, 2022
- Negative laboratory test results
- Alternate diagnosis from healthcare provider
Laboratory and traceback data
FDA, CDC, state partners, and ByHeart collected and tested final product samples. FDA and ByHeart also collected and tested samples of ingredients used in the production of ByHeart Whole Nutrition powdered infant formula, including whole milk powder.
FDA's investigation is ongoing to determine the source of contamination.
FDA and ByHeart testing
The latest and most comprehensive results from product and ingredient testing conducted by FDA and ByHeart are available on FDA's outbreak investigation notice.
State partner testing
The California Department of Public Health confirmed the presence of C. botulinum type A in a culture from an opened can of ByHeart infant formula that was fed to a sick infant in this outbreak.
Public health actions
On November 11, 2025, ByHeart recalled all infant formula products. If you have any ByHeart formula, do not use it and throw it away.
Previous updates
Laboratory data
FDA, CDC, state partners, and ByHeart are conducting product sampling and testing. Additionally, FDA collected ByHeart ingredient samples for analysis, as part of the investigation.
FDA testing
As of January 23, 2026, two samples collected by FDA tested positive for Clostridium botulinum type A:
One is a ByHeart powdered infant formula closed product sample that matches a clinical isolate from an infant included in this outbreak according to whole genome sequencing (WGS) analysis. These samples also match two isolates of whole milk powder, an ingredient that ByHeart uses in the production of ByHeart Whole Nutrition powdered infant formula, which were collected and tested by ByHeart.
The second whole milk powder sample was collected by FDA at a supplier to ByHeart and 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's infant formula, according to analysis conducted by ByHeart.
While these results advance FDA's understanding of the outbreak, FDA's investigation is ongoing to determine the source of contamination.
ByHeart testing
On December 23, 2025, ByHeart publicly reported positive test results for Clostridium botulinum in six of 36 samples of finished product. These six samples were taken from two batches (batch 251261P2 and batch 251131P2), which were both included in the initial product recall.
Additional testing
Sample analysis is ongoing, and additional results will be reported as they become available. The detection of Clostridium botulinum in infant formula, or its ingredients, is complex, and confirmation of results can take several weeks.
Epidemiologic data
Since the last update on December 10, 2025, public health officials have not added any cases to this investigation.
As of December 17, 2025, this outbreak includes 51 infants with suspected or confirmed infant botulism from 19 states (see map). Laboratory confirmation for some cases is ongoing. Illnesses started on dates ranging from December 24, 2023, through December 1, 2025 (see timeline).
All 51 infants were hospitalized and treated with BabyBIG®. No deaths have been reported. The infants range in age from 16 to 264 days and 22 (43%) are female.
Going forward, CDC will provide updates on this outbreak investigation when new information becomes available.
- Symptoms of infant botulism typically occur within 30 days of swallowing Clostridium botulinum spores. The infant formula linked to this outbreak was recalled more than 30 days ago.
- Reports of cases linked to this outbreak have slowed, and no new cases have been added to the investigation since December 10, 2025.
Epidemiologic data
Since the last update on December 3, 2025, public health officials have added 12 cases and 1 state (Ohio) to this investigation.
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 for the outbreak investigation to include any infant with botulism who was exposed to ByHeart formula at any time since the product's release in March 2022.
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. No cases were identified between March 2022 and December 2023. All 10 are confirmed infant botulism cases with documented exposure to ByHeart formula. CDC continues to work with state partners and additional cases may be identified.
As of December 10, 2025, this outbreak includes 51 infants with suspected or confirmed infant botulism from 19 states (see map). Laboratory confirmation for some cases is ongoing. Illnesses started on dates ranging from December 24, 2023, through December 1, 2025 (see timeline).
All 51 infants were hospitalized and treated with BabyBIG®. No deaths have been reported. The infants range in age from 16 to 264 days and 22 (43%) are female.
Epidemiologic data
Since the last update on November 26, 2025, two new cases and one new state (Virginia) have been added to this investigation. Both infants were hospitalized and treated with BabyBIG®.
As of December 3, 2025, this outbreak includes 39 infants with suspected or confirmed infant botulism from 18 states (see map). Laboratory confirmation for some cases is ongoing. Illnesses started on dates ranging from August 9 through November 19, 2025 (see timeline). All 39 infants were hospitalized and treated with BabyBIG®.
No deaths have been reported. For 38 infants with age and 39 with sex information available, they range in age from 16 to 264 days and 15 (38%) are female.
Epidemiologic data
Since the last update on November 20, 2025, six new cases and two new states (Massachusetts and Wisconsin) have been added to this investigation. All six infants were hospitalized and treated with BabyBIG®.
As of November 26, 2025, this outbreak includes 37 infants with suspected or confirmed infant botulism from 17 states (see map). Laboratory confirmation for some cases is ongoing. For 36 cases with illness onset information available, illnesses started on dates ranging from August 9 through November 19, 2025 (see timeline). All 37 infants were hospitalized and treated with BabyBIG®.
No deaths have been reported. For 35 infants with age and sex information available, they range in age from 16 to 264 days and 15 (43%) are female.
Laboratory data
On November 19, 2025, ByHeart reported that testing of unopened ByHeart infant formula at a third-party lab identified Clostridium botulinum in the formula.
The California Department of Public Health confirmed the presence of Clostridium botulinum type A in a culture from an opened can of ByHeart infant formula that was fed to a sick infant in this outbreak.
Additional testing of ByHeart infant formula by multiple agencies is ongoing.
Epidemiologic data
Since the last update on November 14, 2025, eight new cases and two new states (Idaho and Maine) have been added to this investigation. All eight infants were hospitalized and treated with BabyBIG®.
As of November 19, 2025, this outbreak includes 31 infants with suspected or confirmed infant botulism from 15 states (see map). Laboratory confirmation for some cases is ongoing. For 27 cases with illness onset information available, illnesses started on dates ranging from August 9 to November 13, 2025 (see timeline). All 31 infants were hospitalized and treated with BabyBIG®. No deaths have been reported. For 23 infants with age and 24 with sex information available, they range in age from 16 to 200 days and 11 (46%) are female.
Epidemiologic data
Since the last update on November 11, 2025, eight new cases and one new state (Michigan) have been added to this investigation. All 8 cases were hospitalized and treated with BabyBIG®.
As of November 14, 2025, this outbreak includes 23 infants with suspected or confirmed infant botulism from 13 states (see map). Laboratory confirmation for some cases is ongoing. For 22 cases with illness onset information available, illnesses started on dates ranging from August 9 to November 11, 2025 (see timeline). All 23 infants were hospitalized and treated with BabyBIG®. No deaths have been reported. For 22 infants with age and sex information available, they range in age from 16 to 200 days and 10 (45%) are female.
Epidemiologic data
Since the last update on November 8, 2025, two new cases from two new states have been added to this investigation: Kentucky and North Carolina. Both cases were hospitalized and treated with BabyBIG®.
As of November 10, 2025, this outbreak includes 15 infants with suspected or confirmed infant botulism from 12 states (see map). Laboratory confirmation for some cases is ongoing. For 14 cases with illness onset information available, illnesses started on dates ranging from August 9 to November 10, 2025 (see timeline). All 15 infants were hospitalized and treated with BabyBIG®. No deaths have been reported. For 14 infants with age and sex information available, they range in age from 16 to 157 days and 7 (50%) are female.
State and local public health officials are interviewing caregivers about the foods infants were fed in the month before they got sick. Fifteen infant botulism cases have been identified that were fed ByHeart Whole Nutrition powdered infant formula before getting sick.
According to information shared by IBTPP, since August 1, 2025, through November 10, 2025, 84 infants nationwide have received BabyBIG® treatment. Among them, 36 (43%) had any powdered infant formula exposure. Notably, more than 40% (15) consumed ByHeart Whole Nutrition infant formula. This information shows that ByHeart brand formula is disproportionately represented among sick infants in this outbreak, especially given FDA's data that ByHeart represents an estimated 1% of all infant formula sales in the United States. Investigations remain ongoing but have not identified any other infant formula brands or shared exposures that pose a risk to infants at this time.
Laboratory and traceback data
Officials in several states have collected leftover infant formula for testing. Preliminary laboratory results reported by the California Department of Public Health suggest the presence of the bacteria that produce botulinum toxin in an open can of ByHeart infant formula (lot 206VABP/251131P2) that was fed to an infant with infant botulism. Additional product testing by states, CDC, and FDA is ongoing with results expected in the coming weeks.
Public health actions
CDC and FDA are concerned that other lots of ByHeart Whole Nutrition infant may be contaminated and are making infants sick with infant botulism. Parents and caregivers have reported feeding infants in this outbreak different lots of ByHeart infant formula that were not included in the company's initial recall on November 8, 2025. Parents and caregivers are urged to stop using any ByHeart Whole Nutrition infant formula immediately.
Epidemiologic data
As of November 8, 2025, 13 infants with suspected or confirmed infant botulism have been reported from 10 states: Arizona, California (2), Illinois (2), Minnesota, New Jersey, Oregon, Pennsylvania, Rhode Island, Texas (2), and Washington. Laboratory confirmation for some cases is ongoing. Illnesses started on dates ranging from mid-August to November 2025. All 13 infants were hospitalized and treated with BabyBIG®. No deaths have been reported. Infants ranged in age from 16 to 157 days.
State and local public health officials are interviewing caregivers about the foods infants were fed in the month before they got sick. All 13 (100%) reported feeding ByHeart Whole Nutrition infant formula.
Laboratory and traceback data
Officials in several states have collected leftover infant formula for testing. This testing is underway, and results are not yet available but expected in the coming weeks.
Public health actions
FDA has been in contact with the firm and has recommended the firm conduct a voluntary recall due to the number of cases, severity of illness, and the strong epidemiological signal. Today, ByHeart, Inc. agreed to initiate a recall of the two lots of ByHeart Whole Nutrition infant formula (Lot: 206VABP/251261P2 and Lot: 206VABP/251131P2) that were reported to have been consumed by sick infants. FDA is continuing to work with the firm to ensure all potentially impacted products are removed from the market. FDA's investigation is ongoing to determine the point of contamination and if any additional products are impacted.