1.5-month-old baby diarrhea, why?

Diarrhea in a 1.5-month-old is usually from infection. The most common cause at this age is viral gastroenteritis (stomach-intestine inflammation) from viruses like rotavirus or norovirus. Bacterial infections or parasites are possible but rarer.

In breastfed babies, frequent, yellow, liquid/mucous stools are normal and not diarrhea. In true diarrhea, stools are more frequent than normal, much looser, sometimes foul-smelling or greenish.

Other possible causes of diarrhea include:

• Mother's diet: In breastfed babies, certain foods mother eats (excess fruit juice, spicy foods) can cause temporary diarrhea in the baby.
• Formula change or improper mixing: Sudden brand/type change or incorrect water-to-powder ratio causes diarrhea.
• Teething: At this age, teething isn't happening, so this doesn't apply.
• Antibiotics: Antibiotics taken by baby or mother can cause diarrhea.

Most critical warning: In a 1.5-month-old, diarrhea quickly leads to fluid loss (dehydration). If there's fever, vomiting, dry diaper for 6-8+ hours, extreme fussiness, or opposite signs like lethargy, sunken eyes, or skin tenting, go to the emergency room immediately. Diarrhea with these signs is urgent — call 112. At-home treatment beyond continuing breastfeeding isn't enough; consulting pediatrician for appropriate oral rehydration therapy (ORT) if needed is essential.

Note: This information is not medical advice; please consult your doctor about medications and dosing.