Blood in Baby's Stool
The short answer
Seeing blood in your baby's stool is understandably alarming, but the most common cause in young babies is a small anal fissure (a tiny tear from passing stool) or swallowed maternal blood from cracked nipples during breastfeeding. However, blood in stool always deserves medical evaluation to rule out less common but important causes like a cow's milk protein allergy or infection.
By Age
What to expect by age
In newborns, the most common causes of blood in stool are swallowed maternal blood from breastfeeding and cow's milk protein intolerance, which can cause tiny streaks of blood mixed with mucus. Anal fissures from passing stool can also cause small bright red streaks on the outside of the stool. Any blood in a newborn's stool should be evaluated by your pediatrician.
Cow's milk protein allergy remains a common cause in this age range, affecting about 2-3% of infants. Blood may appear as small flecks or streaks mixed with mucus. If your breastfed baby has bloody stools, your doctor may suggest you eliminate dairy from your diet for 2-4 weeks to see if symptoms improve.
As babies start solids, constipation may lead to hard stools that cause anal fissures and bright red blood on the surface of the stool or on the diaper. Infections from bacteria like Salmonella can also cause bloody diarrhea. Intussusception, though rare, can cause currant jelly-like stools and is a medical emergency requiring immediate attention.
In toddlers, the most common causes of bloody stool continue to be constipation-related fissures and infectious gastroenteritis. Allergic colitis may persist or emerge. Recurrent painless rectal bleeding could indicate a Meckel diverticulum or juvenile polyp, both of which your doctor can evaluate.
What Should You Do?
When to take action
- You see a single small streak of bright red blood on the outside of a hard stool, likely from a small fissure
- Your breastfed baby has a small amount of blood in stool and you have cracked or bleeding nipples
- Your baby recently ate beets, red gelatin, or tomatoes and the stool appears reddish but is not actually blood
- You notice small streaks or flecks of blood in your baby's stool, even if your baby seems well
- Blood in stool is accompanied by mucus, suggesting possible allergic colitis or infection
- Your baby has recurring episodes of blood in stool, even if small amounts
- Your breastfed baby has persistent blood-streaked stools and you want to discuss a potential dairy elimination trial
- Your baby has large amounts of blood in the stool, bloody diarrhea, or dark red currant jelly-like stools, which could indicate intussusception or another serious condition
- Your baby has bloody stool along with vomiting, severe abdominal pain with episodes of inconsolable screaming, or lethargy
- Your baby passes black, tarry stools (not from iron supplements) which can indicate bleeding higher in the digestive tract
Sources
Related Resources
Related Digestive Concerns
My Baby's Belly Looks Swollen
A rounded, slightly protruding belly is completely normal in babies and toddlers due to immature abdominal muscles and their proportionally larger organs. However, if the belly becomes suddenly swollen, feels hard and tight, or is accompanied by pain, vomiting, or changes in bowel movements, it needs medical evaluation as it could signal gas buildup, constipation, or rarely, something more serious.
My Baby Has an Anal Fissure (Blood When Pooping)
A small streak of bright red blood on the surface of your baby's stool or on the diaper is most commonly caused by an anal fissure, which is a tiny tear in the skin around the anus from passing hard stool. Anal fissures are very common in babies and toddlers and usually heal on their own with simple measures like keeping stools soft. While this is rarely serious, any blood in your baby's stool should be mentioned to your pediatrician.
My Baby Eats Non-Food Items (Pica)
It is completely normal for babies and young toddlers to explore by putting objects in their mouths. True pica, which is the persistent eating of non-food substances, is uncommon before age two and may be linked to iron deficiency or developmental factors. If your child repeatedly seeks out and eats non-food items past the typical mouthing stage, it is worth discussing with your pediatrician.
Baby Excessive Gas After Starting Solids
Increased gas after starting solid foods is completely normal and expected. Your baby's digestive system is encountering new proteins, fibers, and sugars for the first time and needs time to adapt. The gut bacteria are also diversifying, which naturally produces more gas. This typically improves within a few weeks as the digestive system adjusts to each new food.
My Baby Gulps Air While Feeding
Swallowing some air during feeding is normal for all babies, but excessive air gulping can lead to gas, hiccups, and spit-up. Common causes include fast milk flow, poor latch (if breastfeeding), bottle nipple flow that's too fast or slow, and crying before feeds. Simple adjustments to feeding position, pacing, and equipment can usually help reduce air intake significantly.
Baby Poop Color Changes with Solids
Dramatic changes in poop color after starting solids are completely normal and expected. What your baby eats directly affects stool color - carrots may turn poop orange, spinach makes it green, beets can make it reddish, and blueberries can turn it dark blue-black. As long as your baby is comfortable and the stool is not white, black (tarry), or bright red with blood, these color changes are harmless.