Allergic Colitis - Bloody Stools and Breastfeeding

Pediatrics Question of the Week

Allergic colitis is not a breast milk allergy.
Allergic colitis is usually caused by cow's milk proteins in a mom's milk - it isnot a breast milk allergy.. Photo by Maxim Tupikov

Q. Our three-month-old son is 100% breastfed and has a bloody stool in his diaper. We visited our pediatrician and were told that our baby may be allergic to milk. I believe that the recommendation came because the doctor did not know what else to say or prescribe. To me, the prescription seems odd. We will follow it, though. I have checked and there is no family history of such an occurrence on either my wife or my side of the family. Do you know what other things it may be? Harrisburg, PA

A. This is actually a common problem, but I am hoping that your pediatrician didn't say that your baby was allergic to his mother's breastmilk and that he should stop breastfeeding.

Instead, these babies are usually allergic to the cow's milk that their mother drinks and which passes into her breast milk. These cow's milk proteins trigger allergic colitis, which is the name for this condition in which infants have bloody stools.

It can also be triggered by soy milk and goat’s milk.

It is not an allergy to breast milk.

Baby Formula and Allergic Colitis

Babies fed formula can also have allergic colitis because many forms of infant formula are based on cow's milk. A switch to an elemental formula, like Nutramigen Lipil or Alimentum, usually helps these babies. Because soy formula can also cause allergic colitis, a soy protein-based formula would not be a good substitute.

How long should babies stay on their new formula?

Although some experts recommend continuing the elemental formula until twelve months, at which time you might slowly introduce cow's milk, others might introduce a cow's milk based formula even earlier, after the infant has been on the elemental formula for at least six months.

For babies who can't tolerate Nutramigen or Alimentum, a non-allergenic formula made up of 100% free amino acids are also available, such as Neocate, PurAmino, and EleCare.

Allergic Colitis

Most food allergies are triggered by antibodies and cause immediate symptoms, like hives and difficulty breathing. In contrast, allergic colitis is a delayed-type hypersensitivity reaction and occurs when milk proteins induce an inflammatory response in the intestine.

Signs and symptoms of allergic colitis often begin when infants between the ages of two weeks and six months and might include:

  • bloody stools
  • diarrhea
  • excessive gassiness
  • some fussiness

The treatment is simply to remove whatever is triggering your child’s symptoms, which is usually cow’s milk proteins. After about three to four days, you should then see the symptoms gradually get better.

Keep in mind that most infants with allergic colitis appear well though and just have bloody stools. Seek immediate medical attention if your child has more severe symptoms associated with bloody stools, including excessive fussiness, persistent vomiting, or fever, etc.

Breastfeeding and Allergic Colitis

While babies on formula should switch to an elemental formula, breastfed babies should continue breastfeeding, which the only 'prescription' being that their mother should avoid all milk and dairy products.

And these mothers should talk to their doctor about alternative sources of calcium since drinking cow’s milk and soy milk is a common way for many people to get calcium in their diet.

Other foods can also trigger allergic colitis, and many foods can have 'hidden ingredients' to which you might be allergic, so learn to read food labels and get extra help if this problem continues, especially if you are considering stopping breastfeeding. In addition to milk and soy, other foods to eliminate might include chocolate, citrus fruits, corn, eggs, nuts, peanuts, strawberries, and wheat.

A pediatric gastroenterologist can help if your child with allergic colitis has severe symptoms, including weight loss, or if you are having trouble finding an elimination diet that works.

A very low-allergen elimination diet might be tried if nothing else is working and this would include only eating foods like chicken or lamb, pears, squash, and rice while breastfeeding, in addition to taking a multivitamin and calcium supplement. Since this is a restrictive diet, a registered dietitian should be consulted to make sure you and your baby get adequate nutrition while you are on it and to help as you add foods back to your diet once the symptoms go away.

Fortunately, allergic colitis is often temporary, disappearing by the time your baby is about a year old. By the time these children are 12 to 15 months old, many experts recommend that you start to reintroduce small amounts of milk products.

Having bloody stools can also be caused by intestinal infections or from rectal tears, a common complication of being constipated. In fact, some experts believe that allergic colitis might be overdiagnosed and that too many infants “undergo unnecessary, expensive formula or maternal diet changes that may discourage breastfeeding.”

That makes it important to talk to your pediatrician if your think that your baby has allergic colitis.


Academy of Breastfeeding Medicine. ABM clinical protocol #24: allergic proctocolitis in the exclusively breastfed infant. Breastfeed Med. 2011 Dec;6(6):435-40.

American Academy of Pediatrics. Use of Soy Protein-Based Formulas in Infant Feeding. Pediatrics Vol. 121 No. 5 May 1, 2008. pp. 1062 -1068

Yu, Man-Chun. Allergic Colitis in Infants Related to Cow’s Milk: Clinical Characteristics, Pathologic Changes, and Immunologic Findings. Pediatrics & Neonatology. Volume 54, Issue 1. February, 2013.

Geaney, Casey, MD. Prevalence and Outcome of Allergic Colitis in Healthy Infants With Rectal Bleeding: A Prospective Cohort Study. Pediatrics Vol. 118 No. Supplement 1 August 1, 2006. pp. S13

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