Baby Formula Side Effects

Common baby formula side effects such as rash and digestive issues are most often caused by food allergies, contaminated formula or consuming improperly made formula.

For example, many manufacturers use cow’s milk as an ingredient in baby formulas, yet cow’s milk allergy is a common childhood allergy. About seven percent of babies younger than 12 months of age are allergic to the protein in cow’s milk.

Incorrectly made formula can also harm your baby. The Centers for Disease Control (CDC) warns parents not to use homemade infant formula or buy imported formula online from third-party sellers because of potential problems like insufficient nutrition, dangerous electrolyte imbalances or contamination.

All baby formula legally sold in the US follows the guidelines for safety and nutrition of the Food and Drug Administration (FDA). For example, in August 2021, the FDA announced a baby formula recall for formulas made by Able Groupe because the formulas didn’t contain enough iron. Iron-deficiency anemia in infants can lead to irreversible cognitive and functional development problems, circulatory problems, and decreased oxygen delivery to organs and tissues.

Baby formulas rarely cause serious side effects. However, if left unchecked, food allergies, nutrient deficiencies or baby formula contamination can lead to serious health problems.

Premature babies may also develop a serious condition called necrotizing enterocolitis (NEC) when drinking cow’s milk baby formulas such as Enfamil or Similac. About 1 in 1,000 infants who were born prematurely are affected by NEC. The risk is highest in babies who weigh less than two pounds at birth.

Food allergy symptoms such as swelling of the mouth or throat, hives and vomiting are a medical emergency. These are rare and can happen within days to weeks of an infant starting cow’s milk baby formula. Infants may also have an allergy to soy protein formula. If your infant exhibits any of these symptoms, consider seeking emergency medical attention immediately.

Rarely, a type of bacteria called Cronobacter sakazakii may contaminate baby formula. This can happen during manufacturing, home preparation or during feeding from unsanitary bottles.

In February 2022, Abbott issued a baby formula recall for certain lots of its Similac, Alimentum and EleCare formulas after three complaints of Cronobacter sakazakii infection and one complaint of an infectino by Salmonella in infants who consumed the formula. Later that month, Abbott expanded the recall after the reported death of at least one infant infected with Cronobacter sakazakii. In March 2022, FDA inspectors observed several zones that tested positive for the presence of Cronobacter sakazakii in the Abbott factory that manufactured the affected formulas.

Babies younger than 3 months or those with weakened immune systems are especially susceptible to bacterial infections. Be sure to prepare infant formula in a clean, sanitized area and keep your hands clean.

Necrotizing enterocolitis is a gastrointestinal disease that usually affects infants. It’s fatal in up to 50% of all cases, according to a 2022 study published by the National Center for Biotechnology Information. NEC causes inflammation that may lead to death of tissues in colon. This can lead to holes in the intestines (perforation), sepsis and death.

NEC symptoms include lack of appetite, tenderness or swelling in the abdomen, bloody stools, vomiting and sluggishness. It typically affects babies between 3 and 12 days after birth but can occur many weeks after.

Studies show that premature babies who consume cow’s milk formula alone or as a supplement to breastfeeding are more likely to develop NEC. One of the first studies to link cow’s milk formula to NEC was a 1990 study published in the Journal of Medical Science which showed that NEC was up to 10 times more common in formula-fed premature babies.

Baby formula lawsuits are being filed against the makers of Enfamil and Similac by the parents and guardians of premature babies who developed NEC.

Signs that a baby isn’t tolerating a formula well include diarrhea, constipation, gassiness or frequent vomiting. More serious intolerance issues include bloody stools, congestion or wheezing after eating.

Not all babies experience side effects from switching baby formulas, but when they do, the effects are usually mild digestive issues.

Sometimes your baby’s pediatrician may recommend changing your baby formula. It may be because of food allergies, formula intolerance or other medical concerns. However, changing a baby’s formula too quickly can be a shock to their sensitive digestive system.

Parents should transition a baby to a new formula by gradually including it in feedings. Consider consulting your pediatrician on how to transition your baby to a new formula safely and on how long to test a new formula to avoid side effects.

Editor Lindsay Donaldson contributed to this article.