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Antibiotic Exposure in Infants May Impact Immune Response to Future Allergens

IV Antibiotic drip Newborn

Key Takeaways

  • New research suggests exposure to antibiotics in infancy may lead to increased risk of food allergies.
  • Antibiotics in infancy may alter the gut bacteria long-term
  • It is OK to ask your doctor about the need for antibiotics

Antibiotics are designed to kill invading bacteria but are known to also kill the good bacteria that inhabit the human gut. As adults, we may be able to repopulate the good bacteria with a probiotic supplement but in babies, it’s not so simple. 

New research published by the American Society for Microbiology has shown that antibiotic exposure in infancy could lead to an irreversible altered genetic makeup of the microbiota in babies. The alteration that occurs then impacts the immune system, thus increasing the risk of developing childhood food allergies.

What the Study Showed 

The study exposed baby mice to the antibiotic ampicillin via maternal breast milk. Researchers then monitored the gut microbiota (microscopic organisms in the gut) of the mice as they aged.

Based on the current understanding of normal microbiota, researchers found that the microbiota of the mice exposed to antibiotics remained in an altered state into early adulthood. This was well beyond the period of antibiotic exposure.

The antibiotic-exposed microbiota was also transferred to mice who had not been exposed to antibiotics and found that the altered state persisted even in a different environment. 

From this information, researchers concluded that antibiotics don’t just reduce the number and variety of microorganisms in the gut, they actually alter the genetic makeup of some types which means they continue to reproduce in an altered state.

Study co-author Martin Blaser, MD, says, “Since [the mice] are young, it changes the trajectory of how their microbiota develops—this has parallels for what happens to human children when they receive antibiotics.”

Since this study was conducted on infant mice, more research is needed before official claims can be made with respect to human babies. That being said, there are obvious challenges associated with testing the effects of antibiotics on human babies, given potentially negative outcomes. This research serves as a preliminary warning while spreading awareness of the issue to new mothers considering antibiotic use.

What Is the Impact of Altered Microbiota?

The altered microbiota mostly affected the immune function of the mice. When the studied mice were fed a common food allergen, more of the mice exposed to antibiotics showed signs of an allergic reaction compared to the mice not exposed to antibiotics.

Dr Martin Blaser, MD

We are concerned that the same things are happening to human children and may be fueling the big increases in allergy and asthma in the recent decades.

— Dr Martin Blaser, MD

“In this model, early life antibiotics and maternal antibiotics change the development of immunity, through the antibiotic effects on the microbiome,” explains Blaser. “We are concerned that the same things are happening to human children and may be fueling the big increases in allergy and asthma in the recent decades.”

How Does the Microbiome Impact Food Allergies? 

The combination of many microbiota makes up the microbiome. Blaser explains that the microbiome helps to teach the immune system early in life. He says "...it helps establish 'immunological tone'. So, when the microbiome is disturbed early in life, it can give the wrong lessons to the immune system."

When the immune system is confused, it mistakes normal food for a potential threat and mounts an attack against the food molecules. Outwardly, we see this as symptoms of food allergy such as itchy mouth, hives, and even anaphylaxis.  

Will Avoiding Antibiotics Prevent Food Allergies?

Antibiotics can be life-saving when used appropriately. The key is to use antibiotics only when they are truly needed. In recent years, the World Health Organization has been rolling out Antibiotic Stewardship Interventions across the globe. This is to remind health care providers and the general public to avoid using antibiotics when they are not needed.

Bruce Young, MD

Risks must be weighed for the newborn acutely vs. longer term immunological effects.

— Bruce Young, MD

As a result, most doctors and health care facilities are less likely to prescribe antibiotics unless they truly believe they are necessary. Despite this, as a consumer, you are encouraged to ask questions. It is important to ask your doctor why you need the antibiotics and to discuss any potential alternatives to antibiotic use. 

Your health care practitioner should weigh up the risks versus benefits of prescribing antibiotics for your condition, especially if you are pregnant, breastfeeding or if the antibiotics are for a baby or child.

What This Means For You

Because research is emerging around food allergies, antibiotics, and the microbiome, until there are more definitive answers, please continue to seek the advice of your doctor.

Your health care team understands your personal circumstances and can recommend what is best for you. Doctors maintain ongoing education to stay up to date with the latest research and recommendations that affect you and your baby. Regardless of this, it is always ok to ask questions.

What About Prophylactic Antibiotics?

There are times when antibiotics will be prescribed prophylactically, which means they are given to prevent infection. Obstetrics and Maternal-Fetal Medicine specialist, Bruce Young, M.D. explains that currently, the scientific evidence supports prophylactic antibiotic use to prevent infection in some cases. 

For example, if you are known to have Group B Streptococcus (GBS+) in pregnancy and are planning a vaginal birth, you will likely be given antibiotics in labor to try and prevent a severe infection in your baby.

“GBS prophylaxis is used for patients whose baby is at higher risk for infection with Group B Streptococcus, a dangerous infection in newborns.” Explains Young, “Those infected develop sepsis with a risk of pneumonia, brain damage, and death. The antibiotic prevents infection in nearly 100%.”

Likewise, cesarean births are routinely given antibiotics as a precaution. “Prophylactic antibiotics at [cesarean section] are used because they largely prevented maternal infection in many studies.” Says Young.

For parents who have a cesarean and are concerned about transfer to their baby, Dr Young adds, “The drug can be given after the cord is clamped to avoid the baby getting any.” 

What if My Baby or I Need Antibiotics? 

In health care, there is always a balance of risk versus benefit. If you or your baby do need antibiotics, it’s important you discuss this with your doctor. 

Young explains that sometimes it is important to treat signs and symptoms of infection (such as a persistent fever) before doctors know the exact cause. Trying to find the exact cause may require invasive testing and results can take days to return, in which time a baby or mother can become acutely unwell. 

“As in all cases, risks must be weighed for the newborn acutely vs longer term immunological effects.” Says Young, “However, as more data accumulates the practice may of course change.”

Study authors are working on finding a solution to restore the microbiome after a course of antibiotics to prevent potential long-term implications, but this will take time. Blaser assures parents, “We are working on learning about proper restoration methods and substances.” 

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4 Sources
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