Food Protein-Induced Allergic Proctocolitis of Infancy

Background Information

We make a special point of telling caregivers that a baby’s poop (frequency, color, odor, consistency) is almost never medically important, and changes all the time without warning or cause. The two common situations that are actually important include dry hard pellets of poop (which is the definition of constipation), and bright red blood mixed in with the poop.
Sometime between birth and 4 months of life, around 2% of infants develop frequent episodes of bright red blood in their poop without any other symptoms. They eat well, are satisfied after eating, gain good weight, and have normal development. Of course, there are the normal frequent periods of cluster feeding and fussiness with growth spurts, but all in all, they are normal in every other way.
When the only symptom is persistent episodes (not just one or two) of bright red blood in the stool, we diagnose these babies with something called “food protein-induced allergic proctocolitis (FPIAP) of infancy.” There are a lot of fancy words there, so let’s break them down to understand what’s going on.

Food Protein-Induced

This means that a type of food protein in the baby’s diet is causing the problem. Since this problem starts between birth and 4 months of life, and babies don’t start solid foods until 4-6 months of life, there aren’t a lot of possibilities here. Basically, it’s something from Mom’s diet in the breastmilk, or something in the formula. A study from the year 2000 confirmed there are only 4 dietary triggers of FPIAP:
Cow’s milk (dairy products) - 76% of cases
Egg - 16% of cases
Soy - 6% of cases
Corn - 2% of cases
For babies who are exclusively breastfeeding, this means that one of these 4 foods in Mom’s diet are causing this problem. In babies who eat formula, it means one of these 4 formula ingredients are causing the problem.


Unfortunately, including the word “allergic” here is actually misleading, and causes a lot of confusion for caregivers (and medical providers!). When most people hear this word, they think of the dangerous kind of allergies that require an epipen, such as peanut, egg, or bee sting allergies. In FPIAP, the allergy is not life threatening, or even dangerous. Instead, “allergic” simply means that the baby’s digestive system is unable to break down one (or several) of the 4 foods discussed above. This causes inflammation and bleeding.


This refers to the specific part of the digestive system that is unable to break down the food protein. “Procto” means rectum (which is the last part of the GI tract before the anus). “Colo” means the colon (which comes right before the rectum). “Itis” means inflammation, as explained at the end of the last paragraph.

How Worried Should I Be?

Not worried at all. The good news is that once we figure out which food is causing the bleeding, and remove it from the diet, the bleeding resolves in 1-2 weeks. Until the bleeding stops, we don’t need to worry about dangerous blood loss or long term problems caused by the intestinal inflammation.

How Do We Fix This?

In exclusively breastfed babies, we remove the possible foods from Mom’s diet, one by one, until the bleeding stops. It can take up to 2 weeks to completely remove any traces of the problem food from Mom’s body and breastmilk, so each time we remove a food, we give it 2 weeks before moving to the next food. We start with the most common cause, by removing all dairy products ( including other animal milk such as goat's milk), from Mom’s diet. Here’s a link from for a list of all the hidden dairy sources you may not be aware of.
In exclusively formula-fed babies, we change them to a different category of formula (extensively-hydrolyzed or amino acid based) that has already broken down these problem food proteins. These options include:
1. Extensively-hydrolyzed casein-based formula: Enfamil Nutramigen and Similac Alimentum
2. Extensively-hydrolyzed whey-based formula: Gerber Extensive HA
3. Amino acid-based formulas: Abbott Elecare and Nutricia Neocate
Any one of these formulas usually fixes the problem for good.

Is This a Life-Long Problem?

Not even close! The problem food will be tolerated by around 50% of babies at 6 months of life, 95% of babies at 9 months of life, and 100% of babies at 12 months of life. For this reason, we typically return to normal formula or reintroduce the foods to Mom’s diet at 6 months of life, and monitor for return of blood.

What If Bleeding Returns?

If bleeding returns after reintroduction at 6 months, we go back to the plan that was working, and try again at 9 months. If bleeding returns at 9 months, we try again at 12 months.