Recent tests have revealed that ByHeart’s infant formula, linked to a botulism outbreak affecting numerous infants, might have been contaminated across all products. This alarming discovery has raised significant concerns among parents and health officials.

In an announcement made on Monday, the company disclosed that laboratory analysis of 36 formula samples from three separate batches identified five samples containing a strain of bacteria known for causing botulism, a rare but potentially lethal disease.

“Given these findings, we cannot eliminate the possibility that all ByHeart formula products may be compromised,” the company stated in their release.

Since the outbreak’s onset in August, health authorities have reported that at least 31 infants across 15 states fell ill after consuming ByHeart formula. Additionally, there have been instances dating back to November 2024 where other infants, not included in the current outbreak statistics, were treated for botulism after using the product.

The detected bacteria, Clostridium botulinum type A, can be distributed inconsistently in powdered formulas. Although not every baby who consumes the contaminated formula will fall ill, experts warn that infants under the age of one are particularly vulnerable.

ByHeart recalled all of its formula nationwide on Nov. 11. However, some product has remained on store shelves despite the recall, according to state officials and the U.S. Food and Drug Administration.

Parents and caregivers should stop feeding the formula to babies immediately and monitor the children for symptoms, which can take up to 30 days to appear.

Infant botulism occurs when babies ingest spores that germinate in their intestine and produce a toxin. Symptoms include constipation, difficulty sucking or feeding, drooping eyelids, flat facial expression and weakness in the arms, legs and head. The illness is a medical emergency and requires immediate treatment.

At least 107 babies nationwide have been treated for botulism with an IV medication known as BabyBIG since Aug. 1, health officials said. In a typical year, less than 200 infants are treated for the illness.

To report an illness tied to the outbreak, contact an FDA consumer complaint coordinator or fill out an online MedWatch form.

Consumers who bought ByHeart on the company’s website on or after Aug. 1 can receive a full refund, an expansion of its previous policy, the company said.