Causes of Diarrhea in Four-Month-Old Babies

Infant bowel habits and characteristics change quite abruptly during the first few months of life. By about four-months of age a baby may have diapers frequently consisting of soft, liquid or solid stools. A breastfed baby will pass watery or seedy stools that have minimal shape. These are not signs of diarrhea. Infant diarrhea is described as bowel movements that are more frequent, greater in volume, watery and foul-smelling. Baby diarrhea can be due to illness or diet.

Dietary Changes suggests that even a minor change in a baby's diet can result in loose stools. A bottle-fed infant isn't likely to develop a sudden bout of diarrhea as a result of the formula, but if she has suffered from diarrhea, bloating, constipation and other digestive discomforts since beginning the formula, a doctor may recommend a different brand or type.

A breast-fed baby can have diarrhea in response to the mother's diet. Her intake of dairy, spicy foods and even caffeine can upset a baby's sensitive tummy and cause diarrhea. Mothers can keep a food log to help identify what foods trigger diarrhea, fussiness, gassiness and other discomforts in a breastfed baby.

An infant can have a sensitivity or intolerance to milk proteins, known as dairy allergy or lactose intolerance. These issues can develop around 4 months but they will likely be present soon after birth. points out that sometimes a short bout of diarrhea is just the body's way of adjusting to digesting foods instead of absorbing nutrients provided in the womb 2.


Diarrhea is a common side effects of many antibiotics. This is true not just for babies but also for adults and children. A mother on antibiotics can pass the medicine to her baby during breastfeeding, which may result in infant diarrhea. The diarrhea should resolve within a day or two of finishing the prescription.

Intestinal Infections

Various bacteria, viruses and parasites can cause diarrhea in an infant. This can be contracted by touching an item contaminated with the organism and putting the hands or the object into the mouth. Such infections are often passed from caregivers and others who handle the baby. indicates that several viral and bacterial infections are common in childhood and can easily be spread to an infant 2. These include rotavirus, E. coli, salmonella and Giardia. This organisms are often found in foods, like raw meats and poorly washed produce.

In addition to diarrhea, the infant may develop a fever, abdominal cramps, vomiting, lethargy and a poor appetite from an intestinal infection. Sometimes the diarrhea contains blood, especially with a bacterial infection. Treatment is not usually offered but the infant is monitored for persistent illness and dehydration.

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