Reddish-brown baby poop is usually caused by something harmless, like a food the baby ate or a medication. But because red in a diaper can also signal blood, it’s worth figuring out which category your baby falls into. The cause almost always becomes clear once you consider your baby’s age, diet, and any recent medications.
Foods That Turn Stool Reddish Brown
Once your baby is eating solids, certain foods are the most common and least worrying explanation. Beets, tomatoes, red berries, red gelatin, and fruit punches can all tint stool a reddish or reddish-brown color. The pigments in these foods aren’t fully broken down during digestion, so they pass through and show up in the diaper looking surprisingly vivid.
If your baby recently tried a new red or deeply pigmented food, that’s likely your answer. The color change usually appears within 12 to 24 hours of eating and clears up once the food works its way out of the system. No treatment is needed.
Antibiotics and Iron Supplements
A common antibiotic prescribed for ear infections and other childhood illnesses can turn stool a striking red or reddish-brown when a baby is also getting iron, whether from a supplement or iron-fortified formula. The antibiotic (or one of its breakdown products) binds to iron in the gut, forming a complex that colors the stool but contains no actual blood. The color can look alarming enough that parents rush to the emergency room, and even some clinicians don’t immediately recognize the connection because this interaction isn’t always listed prominently in drug information.
A quick way to confirm: the red stools typically appear about 48 hours into treatment and resolve within hours of stopping the antibiotic. If your baby is on an antibiotic and an iron-containing product at the same time, mention both to your pediatrician before assuming the worst.
Anal Fissures
Small tears in the skin around the anus are one of the most common reasons babies have actual blood in their stool. These fissures happen when a baby passes a hard or unusually large stool. You’ll typically see bright red blood coating the outside of the stool or streaked on the diaper, not mixed throughout. The amount is usually small.
Fissures are painful, so your baby may strain, cry during bowel movements, or seem reluctant to go. They generally heal on their own once the stool softens. If your baby is on solids, increasing water and fiber-rich foods can help. For younger babies, your pediatrician may suggest adjustments to feeding.
Milk Protein Allergy
Allergic colitis affects roughly 2 to 3 percent of infants and is caused by a reaction to proteins in cow’s milk, whether from formula or passed through breast milk. A baby with this condition may be unusually fussy, gassy, and hard to console. The hallmark sign in the diaper is flecks or streaks of blood mixed with mucus in otherwise normal-looking stool.
The blood is often so small in quantity that it’s invisible to the naked eye and only detected through a lab test. If your pediatrician suspects allergic colitis, the usual approach is removing cow’s milk protein from the baby’s diet (switching to a specialized formula, or eliminating dairy from the breastfeeding parent’s diet) and watching for improvement over a couple of weeks.
Swallowed Blood in Newborns
In the first few days of life, a newborn can swallow maternal blood during delivery or from cracked nipples during breastfeeding. This swallowed blood passes through the digestive tract and shows up as maroon-colored streaks in meconium (the dark, tarry first stools) or as blood-streaked stools shortly after. It can also appear as dark, coffee-ground-like spit-up.
Doctors can distinguish swallowed maternal blood from the baby’s own blood using a simple lab test called the Apt test, which identifies whether the blood contains adult or fetal hemoglobin. If the blood turns out to be maternal, no treatment is needed for the baby. This is a common and temporary finding in the first week or two of life.
Normal Stool Color Changes
Baby stool goes through a rapid color evolution in the early weeks. The very first stools are black and tar-like (meconium), and within two to three days they transition to greenish, then yellowish or mustard-colored stools for breastfed babies, or tan to brownish for formula-fed babies. During these transitions, you may see colors that look brownish-red or rusty, especially as meconium mixes with newer milk-based stool. This in-between color is normal and passes quickly.
As babies grow and start solids, stool color becomes even more variable. Brown, green, orange, and yellow are all within the normal range on any given day, depending on what your baby ate.
When Reddish-Brown Stool Needs Urgent Attention
Most causes of reddish-brown stool are benign, but certain patterns point to something more serious. Stool that looks like currant jelly (dark red, maroon, and gelatinous) can be a sign of a condition called Meckel’s diverticulum or intussusception, both of which need prompt medical evaluation. This type of bleeding is often painless, which can be misleading.
Seek immediate care if your baby has any of the following alongside bloody or reddish-brown stool:
- Fever, rapid heart rate, or pallor, which suggest a systemic illness or significant blood loss
- Lethargy or poor feeding, especially if your baby is harder to wake than usual
- Large volumes of blood or more than five bloody stools in a day
- Abdominal pain or distension, particularly if your baby draws their knees to their chest or screams inconsolably
A single diaper with a reddish-brown tinge in an otherwise happy, feeding baby is rarely an emergency. But if you’re unsure whether what you’re seeing is blood or food, your pediatrician can test a stool sample in the office. The test takes minutes and gives a definitive answer.