While bloody baby poop is usually harmless, it can sometimes indicate a medical problem that requires treatment. Here’s how to determine the cause and find appropriate care.
baby sitting on examination table
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You can learn a lot about your little one's development by looking in their diaper. During your baby's first few months, you'll notice plenty of brown, yellow, and green poop—all of which are normal colors for breastfeeding and formula-feeding infants, says Nanci Pittman, M.D., a pediatric gastroenterologist and assistant professor of pediatrics at Mount Sinai School of Medicine in New York City. But blood in the stool, whether it's small flakes or large streaks, may indicate a medical problem.

Keep in mind: Red poop doesn't always mean blood; it can also result from eating red-tinged foods like tomatoes, beets, or fruit punch. That said, if your little one's stool appears bloody, or if it's consistently turning out red, it's important to determine the cause and seek appropriate care.

Here are the top causes of bloody baby stool and when to visit the pediatrician.


Constipation is rare in babies, but it sometimes happens—usually from a milk-protein allergy, starting solids, or not getting enough fluids. Telltale symptoms include a prolonged absence of stool, hard poop that look like pebbles, discomfort, and a firm-feeling belly. Constipation might also cause tiny tears in the anus (anal fissures), which cause bloody streaks on the surface of the stool. Most anal fissures heal themselves, but if you suspect constipation, try changing your baby's diet. For example, you can eliminate dairy, add more fiber, or ensure they're getting enough fluid. Talk to your doctor for more information on combating constipation.


Bloody baby stool can signal certain bacterial and parasitic infections, including gastroenteritis, salmonella, shigella, staphylococcus, C. Difficile, or campylobacter. That's because infections often cause intestinal inflammation and tiny ruptures that let blood leak out. Diarrhea commonly comes with infections, so if you notice diarrhea with bloody poop, alert your doctor right away. They might prescribe antibiotics to help treat it.

Food Allergies

Notice bloody poop after changing your baby's diet? You might blame food allergies that inflame the colon, allowing blood to trickle into the stool. The most common food sensitivities are to milk and soy, but your baby could also be allergic to wheat, oats, rye, or something else. Food allergies usually present with other symptoms too, including skin rashes, vomiting, and diarrhea. Your medical practitioner can help diagnose allergies and come up with a treatment plan. (Note that breastfeeding babies can also react to something in the mother's diet).

Maternal Nipple Injuries

If a breastfeeding mother has cracked nipples, the baby could swallow some of the blood, leading to dark red or black flecks in the stool. This usually isn't cause for concern.

Gastrointestinal Tract Bleeding

In rare cases, dark red or black stool indicates bleeding along the upper gastrointestinal tract. GI bleeding often comes from a severe illness or injury, so it's vital to alert your doctor immediately. 

Less Common Causes of Bloody Stool

Bloody baby stool might also have less common causes. For example, streptococcus bacteria could get around the anus, resulting in inflammation and bloody poop. Your baby might also suffer from colitis (inflammation of the large intestine), Crohn's disease, or necrotizing enterocolitis. 

When to Call the Doctor

Parents should always let the pediatrician know about bloody stool. However, they should seek care immediately if baby is younger than 12 weeks old, or if they notice the following symptoms:

  • An excessive amount of blood in the stool
  • Fussiness or inconsolable crying
  • Black stool 
  • Fatigue
  • Poop with a tarry consistency
  • Stomach pain
  • Anal injury
  • Refusal to eat or drink
  • Bloody stool with diarrhea
  • Bloody stool with fever
  • Blood stool with mucus

Make sure to give your doctor a detailed overview of your baby's symptoms. Is the blood dark red or bright red? Does it appear as streaks on the outside of the stool, or is it mixed throughout the poop? Does your baby have fever, diarrhea, or other unusual symptoms? Keeping a detailed log will help your doctor reach a diagnosis. 

In the office, the pediatrician may also analyze your baby's stool and examine them for signs of infection or illness. Treatment depends on the exact cause of bloody baby stool. Most of the time, though, bloody stool should not result in any long-term health issues.