Can Breastfeeding Be Unhealthy?

Breastfeeding is almost always the best way to feed your baby. A very few medical conditions -- yours or your baby's -- make breastfeeding a dangerous or unhealthy option. Despite what you might hear, babies are almost never "allergic" to breast milk or unable to tolerate it for other reasons. They might be allergic to some of the foods in your diet, but changing your diet removes the risk.

Galactosemia

The main sugar in milk, lactose, consists of two sugars, galactose and glucose. A very small number of infants -- around 1 in 30,000 to 60,000, according to the Genetics Home Research website -- lack the enzymes to break down galactose and absorb it into the body. If a baby with this condition drinks breast milk, he will become malnourished and lethargic, experiencing both physical and developmental delays. He might also develop severe infections and/or shock, liver disease and kidney problems. Galactosemia is one of the few absolute contraindications to breastfeeding your baby.

Phenylketonuria (PKU)

Doctors test all babies born in United States hospitals for phenylketonuria, better known as PKU. Around one in 10,000 to 15,000 infants in the United States tests positive for this genetic disorder at birth, the March of Dimes reports. Babies with this disorder lack enzymes that break down phenylalanine, an amino acid. Phenylalanine then builds up in the blood and can cause death. Babies with this disease must avoid milk. Breast milk has lower levels of phenylalanine than cow's milk; you might be able to nurse your baby for part of his nourishment and supply the rest with phenylalanine-free formulas. This might not be possible, though, depending on the severity of his disease.

Congenital Lactose Intolerance

Lactose intolerance affects around 65 percent of people worldwide, but generally doesn't develop until after age 3 or later, when babies no longer rely on milk as their primary food. Congenital lactose intolerance, which occurs at birth, affects just 1 in 60,000 or fewer newborns, according to the Genetics Home Reference. Babies with this condition can develop severe diarrhea, which leads to dehydration and weight loss, if they consume breast milk.

Maternal Conditions

If you have certain health conditions or take some medications, it's better for your baby if you don't breastfeed. These include human immunodeficiency virus, or HIV, or active and untreated tuberculosis. Other contraindications to breastfeeding include street drug use or use of chemotherapy or anti-retroviral medications. If you're undergoing radiation treatment, you should not be breastfeeding while in active treatment. If you have any chronic or acute health condition, ask your doctor if it's safe to breastfeed your baby.