What causes blood in baby’s stool?

By Kelly Bonyata, BS, IBCLC

Many cases of blood in infant stools have no known cause. If the baby is otherwise well and growing, blood in the stool often resolves on its own, but this should always be checked out by baby’s doctor.

The color of the blood gives you a clue about where it originated. Blood originating in the colon or rectum tends to be red and may only streak the outside of the stool. If the blood originates further up the GI tract, then the blood is generally darker in color (dark brown/maroon, black) and mixed throughout the stool instead of just on the outside.

Some potential causes of blood in baby’s stools:

  • A common cause of blood in an infant’s stool is a slight anal tear (fissure) from baby straining with the passage of the stool. The small amount of blood from an anal fissure tends to look like a red streak on the outside of the stool.
  • Another common cause of blood in the stools of infants is food allergies. The top allergens are cow’s milk products and soy. See Dairy and other Food Sensitivities in Breastfed Babies for more information.
  • A third common cause: If mom has a cracked nipple or other bleeding, then baby may ingest some blood from mom (this is not harmful to baby), which may show up in baby’s stool.
  • Occasionally, blood in the stool may be due to breastmilk oversupply. Per Dr. Jack Newman, bloody stools in some babies have been eliminated completely by resolving mom’s oversupply. This can be done by following the usual management procedures for oversupply; it can also be helpful to use breast compressions to increase the amount of fat that baby gets while nursing.
  • There are several case reports of a baby beginning to have mucous and/or blood in the stool after starting vitamin/fluoride drops, where the blood disappeared after the drops were discontinued.
  • Blood in the stool may also be caused by a temporary case of lactose intolerance, due to an intestinal infection.
  • Certain kinds of infectious diarrhea can cause bloody stools in babies, including Salmonella and C. Difficile. C. Difficile is a bacteria that grows in the gut if the bacterial balance has been upset; the toxin can cause injury to the mucosa and bloody stools. Breastfed babies tend to have less severe symptoms than non-breastfed babies because breastmilk inhibits the growth of the bacteria.
  • Various forms of colitis, intussusception, or other intestinal disorders are other possible causes.

Does blood in the stool require a trip to the emergency room?

You should always talk to baby’s doctor if there is blood in baby’s stool, but whether or not this requires an emergency visit would depend upon your child’s behavior. If baby is happy and seems healthy, then call your doctor to make an appointment. If baby is experiencing abdominal pain, significant bleeding in the stool, diarrhea, vomiting, and/or fever, then more urgent medical care is indicated. Per Dr. Jay Gordon, “Persistent or increasing blood in the stool or blood mixed with mucus (described as “currant jelly” stool in the texts) requires an immediate call to your doctor.”

Additional Information

Articles on this subject

Journal articles on this subject

Allergic Proctocolitis in the Exclusively Breastfed Infant. Academy of Breastfeeding Medicine Protocol #24, from Breastfeeding Medicine ( 2011) Volume 6, Number 6, pp. 435-440.

Walker M. Breastfeeding Management for the Clinician: Using the Evidence. Boston: Jones and Bartlett, 2006: 335-336.

Lawrence R, Lawrence R. Breastfeeding: A Guide for the Medical Profession, 6th ed. Philadelphia, Pennsylvania: Mosby, 2005: 521-523, 549.

Riordan J. Breastfeeding and Human Lactation, 3rd ed. Boston and London: Jones and Bartlett, 2004: 576-579.

Mohrbacher N, Stock J. The Breastfeeding Answer Book, Third Revised Edition. Schaumburg, Illinois: La Leche League International, 2003: 131-133.

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