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FDA News Release

FDA Raises Concerns About Probiotic Products Sold for Use in Hospitalized Preterm Infants

Warning Letters Issued to Two Companies for Illegally Selling Probiotic Products to Treat Diseases in Preterm Infants

For Immediate Release:


As part of the U.S. Food and Drug Administration’s commitment to protecting public health, the agency is advising the public, including healthcare providers, of the possible risks that products containing live bacteria or yeast, which are commonly called probiotics, pose to preterm infants in hospital settings. The agency recently sent a letter to healthcare providers warning them about this topic and has issued two warning letters to companies for illegally selling their products for use in treating or preventing certain diseases in preterm infants.

Probiotic products contain live organisms such as bacteria or yeast and are commonly marketed as foods, including as dietary supplements. The FDA is concerned as these products can be dangerous for preterm infants and are being illegally sold to treat or prevent diseases in preterm infants in hospital settings, such as to reduce the risk of necrotizing enterocolitis. Preterm infants who are administered a probiotic product are at risk of invasive, potentially fatal disease, or infection, caused by the bacteria or yeast contained in the probiotics.

The FDA is aware that certain probiotic products used in hospital settings to prevent necrotizing enterocolitis have contributed to invasive disease, including one infant death in 2023, and have been associated with more than two dozen other reported adverse events in the United States since 2018. The agency is also concerned about and is investigating reports that these products may have contributed to additional adverse events, including death, and is working to obtain the proper evidence and medical records, where possible. Any death or adverse event in an infant following the use of a probiotic product is very concerning, and the FDA is actively working with healthcare providers to better understand the link between the probiotic products used and the adverse events in preterm infants reported by these institutions. 

Importantly, the FDA has not approved any probiotic product for use as a drug or biological product in infants of any age. Unapproved, unlicensed probiotics that are used to treat or prevent a disease or condition in preterm infants have not undergone the agency’s thorough premarket evaluation for safety and effectiveness. Further, they have not been evaluated for compliance with the agency’s rigorous manufacturing and testing standards for drugs and biological products, including testing for other organisms. For these products to be lawfully marketed as drugs and biological products, the FDA requires approval of a Biologics License Application to ensure they have been appropriately evaluated. In the absence of an approved product, healthcare providers who administer products containing live bacteria or yeast to treat, mitigate, cure or prevent a disease or condition are required to submit an Investigational New Drug application to the agency to ensure the investigational use of an unapproved product is conducted with the appropriate safeguards.

“Adverse events in any infant following the use of a probiotic are a concern to the FDA. We especially want to make clear that products containing live microorganisms may present serious risks to preterm infants in hospital settings,” said Peter Marks, M.D., Ph.D., director of the FDA’s Center for Biologics Evaluation and Research. “With today’s message, we want to warn parents, caregivers and healthcare providers that if these products are used for the prevention or treatment of disease, they have not undergone the agency’s rigorous premarket process to evaluate their safety, effectiveness and quality for these medical uses.”

The agency is committed to ensuring that any violations and safety issues presented by these products are addressed by their manufacturers. The agency issued a warning letter to Abbott Laboratories on Oct. 24, 2023, for its product, Similac Probiotic Tri-Blend, which contains B. infantis (Bb-02), S. thermophilus (TH-4) and B. lactis (BB-12). Of note, this product is not an infant formula and is not related to the previous issues the agency has noted with powdered infant formula manufactured by Abbott Nutrition. Abbott has agreed to discontinue sales of its Similac Probiotic Tri-Blend product and is working with the FDA to take additional corrective actions. 

The warning letter notes the company sells the probiotic product for use in hospital settings for preterm infants. Based on the intended uses on the company’s websites and Abbott’s marketing materials, the product is an unapproved new drug and an unlicensed biological product being sold in violation of the Federal Food, Drug, and Cosmetic Act (FD&C Act) and the Public Health Service Act. Additionally, the product is an adulterated dietary supplement under the FD&C Act because, when intended for consumption by preterm infants, the Bb-02 and TH-4 ingredients have not met the applicable safety requirements. 

The agency also recently issued a warning letter to Infinant Health, Inc (formerly Evolve BioSystems Inc.) regarding its probiotic product, Evivo with MCT Oil, an unapproved and unlicensed product sold for use in treating or preventing disease in preterm infants, in violation of the FD&C Act and the Public Health Service Act. The product was intended to be added to food for preterm infants and as such was also found to be an adulterated food under the FD&C Act. This product has since been voluntarily recalled and is no longer available in the U.S.

“Protecting public health, especially of the most vulnerable populations such as preterm infants, is one of the highest priorities for the FDA,” said Jim Jones, the FDA’s Deputy Commissioner for Human Foods. “We are encouraging all involved in the care of preterm infants, including parents, caregivers and healthcare providers, to be aware of the possible risks associated with the administration of probiotic products to preterm infants in hospital settings. The FDA continues to investigate these incidents and is committed to using our available resources and authorities to identify and address potentially unsafe products in the market.”

The FDA understands there are conflicting data in the literature on the safety and effectiveness of probiotics for the prevention of necrotizing enterocolitis, and that the study of the use of probiotics has been complicated by several factors, including the use of different probiotics in different trials. Because of the potential for harm posed by these products in highly vulnerable individuals, such as preterm infants, the agency urges the industry, clinical and research funding communities to focus on high quality clinical trials with products meeting quality criteria to provide definitive evidence to inform the use of these products by healthcare providers and, where appropriate, to support applications for drugs and biological products for use in infants of any age. 

The agency continues to carefully review and investigate adverse event reports for probiotics. To inform the agency’s surveillance efforts, and to better understand these issues to help protect public health, the FDA encourages healthcare providers and caregivers to report adverse events following use of probiotics to the manufacturer, the FDA’s MedWatch program and CFSAN’s Adverse Event Reporting System. Caregivers may also speak with their healthcare provider regarding concerns or questions with these products.

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The FDA, an agency within the U.S. Department of Health and Human Services, protects the public health by assuring the safety, effectiveness, and security of human and veterinary drugs, vaccines and other biological products for human use, and medical devices. The agency also is responsible for the safety and security of our nation’s food supply, cosmetics, dietary supplements, radiation-emitting electronic products, and for regulating tobacco products.


Carly (Kempler) Pflaum
Courtney Rhodes

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