Blood in Stool / Iron Deficiency

Digestive Symptoms of Cow'S Milk Protein Allergy.

During the first few months of an infant’s life they often have colored stools, including yellow, green and even stools with streaks of blood (hematochezia). 

This may be frightening for parents, but it is relatively common in babies and is usually not a sign of a serious problem.1 

However, when it is chronic it can lead to iron deficiency (ID) or iron deficiency anemia (IDA). Iron-deficiency with and without anemia may be a manifestation of chronic undiagnosed CMPA.2. 

In one study they reported ~16% of young children had iron deficiency with or without anemia due gastrointestinal blood loss related to cow’s milk allergy.2 In a more recent study they reported that ~14% of children <4 years with IDA had CMPA.3 


What Causes
Blood in Stools
and Iron
deficiency in

Straining when passing a hard stool, for example, can cause small tears in the area around the anus, or anal fissures, which can result in blood streaks in the nappy. Chronic CMPA can also be a cause of hematochezia and ID with or without anemia, in young children.

This can be due to chronic blood loss resulting from damage to the gastrointestinal tract related to CMPA. Some of the complex condition like food protein-induced enterocolitis syndrome (FPIES) or eosinophilic gastrointestinal disease have been known to cause blood loss.3

Could It Be a
Symptom of
Cow’s Milk
Protein Allergy?

Blood in stools or hematochezia which leads to ID or IDA can occur in some cases of severe undiagnosed CMPA e.g., non–IgE-mediated CMPA with gastrointestinal involvement.4

However, CMPA may not be the only cause as hematochezia is commonly seen in infants (Bajerova et al., 2022). A specific diagnostic work up according to the presence of other symptoms such as, infection, anal fissure or a rectal prolapse, is therefore recommended.5

An immediate referral to a physician is required in sick infants with haematochezia. 

Overview of Symptoms

Respiratory icon


Up to 30% of affected infants with CMPA have respiratory symptoms15,20

Anaphylaxis icon


Anaphylactic shock is a severe, immediate, allergic reaction, which can affect many organ/systems

Skin icon


Up to 75% of infants with CMPA can have skin-related symptoms21

General Symptoms icon


Inconsolable crying is very common in infants with CMPA associated with sleeping problems and food refusal