When is blood in a baby's stool concerning, and what causes it?

Most bloody stools are not immediately life threatening.

However, it is still important for caregivers to consult with a doctor anytime blood is in a baby’s stool. A doctor can diagnose the cause and recommend the appropriate treatment.

Caregivers should go to the emergency room if a baby:

• has bloody diarrhea
• has bloody stools and a fever or other signs of illness
• was premature and has blood in their stool
• has bloody stools and a swollen stomach
• does not want to eat
• seems lethargic or very sick

The following chart details what different poop colors may mean in babies, including red or bloody stool. Blood in the stool may appear as red streaks or dark flecks. It may also cause the entire stool to appear dark red or even black.

If a baby’s stool appears red or dark in color, it does not always mean the baby is passing blood.

Diet or medication

Certain foods, such as tomatoes, beets, or food colorings, may cause red streaks or chunks in a baby’s stool. So, caregivers should pay close attention to recent foods the baby has eaten.

Some medications may also cause dark or red stools. Caregivers should consider whether the baby has had any medications that could affect their stool.

A doctor can also help determine if food or medication is the cause of the discoloration. No treatments are necessary in this case.

There are several possible causes if the stool appears streaked with red or dark colors due to blood. The most common causes include:

Constipation

Some babies have very hard or large bowel movements or go long periods without a bowel movement. Babies with constipation may strain to poop.

This can cause stools with streaks or flecks of blood on the outside as the poop leaving the body causes tiny tears in the anus. Doctors call this an anal fissure.

Most anal fissures heal on their own. However, because they cause an open wound in an area exposed to lots of bacteria, they can become infected in rare cases.

A doctor may recommend ointment or cream to ease the pain. A baby may also need diet changes to reduce the risk of constipation.

Learn some home remedies for baby constipation here.

Blood in breast milk

Sometimes, breast milk contains blood. This often occurs because the person breastfeeding has cracked or injured nipples.

When this happens, the baby may swallow some blood during a feed. This can cause faint streaks of blood in the baby’s stool or make an entire stool look reddish in color.

It is not dangerous for a baby to swallow blood during breastfeeding. However, if the person breastfeeding has HIV or AIDS, they should speak with a doctor about the risks associated with breastfeeding and blood in breast milk.

If blood is present in breast milk, it is important for people to treat any injury to the nipple, since chronic nipple damage can disrupt breastfeeding and cause infections.

The person breastfeeding may consider working with a lactation consultant to adjust the latch and heal the affected area.

Food allergies and sensitivities

Babies with food sensitivities or allergies — most often to cow’s milk — may have small streaks or flecks of blood in their stool. This may subside within the first two months of life.

If caregivers frequently notice blood-tinged stools, they should consult with a doctor.

Babies with allergies or sensitivities can react to breast milk or formula. A doctor may suggest various tests to identify an allergy. They may also suggest changes to the breastfeeding person’s diet or the type of formula.

Diarrhea

Bloody diarrhea may signal a bacterial infection, such as salmonella or E. coli.

While these conditions often clear on their own, they can cause dangerous dehydration in babies. Therefore, it is important for caregivers to speak with a doctor if a baby is experiencing diarrhea.

Other symptoms of an infection include fevers, irritability, and feeding difficulties.

Even if they are not showing other symptoms, babies experiencing bloody diarrhea require medical care.

Upper GI bleeding

Dark blood in the stool or black stools may signify that the upper part of the baby’s gastrointestinal tract, such as their stomach, esophagus, throat, or even their nose, is bleeding.

Sometimes, this happens after a traumatic injury, such as choking. In other cases, upper GI bleeding occurs because of a severe infection or illness.

Upper GI bleeding is a medical emergency, and the baby should receive care immediately.

Necrotizing enterocolitis

Certain serious illnesses can cause blood in the stool. Some babies may get diarrhea with blood and other symptoms when they have one of these conditions.

One of the most dangerous conditions is necrotizing enterocolitis. This condition causes damage to the intestinal lining, leading to gastrointestinal symptoms. This damage can lead to gut bacteria invading the bloodstream, causing infection.

It is more common among preterm infants and babies with other health conditions. Many cases occur before newborns leave the hospital. Caregivers may notice that the baby’s stomach appears swollen or that they do not want to eat.

Necrotizing enterocolitis can be fatal. Therefore, a doctor needs to evaluate any infants that pass a bloody stool or have other risk factors.

Not all bloody stools need treatment. Mild constipation and anal fissures often go away on their own.

However, as babies are more vulnerable to certain infections, a doctor will probably seek to diagnose the cause and treat it.

The right treatment depends on the cause. It may include:

• Pain treatment for anal fissures: A doctor may recommend sitz baths or creams.
• Surgery: A blockage in the intestines that causes bleeding could require surgery.
• Antibiotics: A doctor may prescribe antibiotics for certain infections or, rarely, to treat an infected fissure.
• Fluids: A doctor may recommend intravenous (IV) fluids or electrolyte drinks for a baby whose diarrhea causes dehydration.
• Diet changes: Eating more fiber may help with constipation in older babies. Younger babies may need to switch formulas or drink more breast milk. Sometimes, the person breastfeeding has to change their diet.

Blood in a baby’s stool may indicate a temporary issue, such as constipation. However, it can also signal a life threatening medical condition, such as necrotizing enterocolitis.

It can be difficult for caregivers to diagnose the cause at home, so it is crucial to get a professional diagnosis.

Most issues that cause a bloody stool are highly treatable. Even when there is a serious underlying problem, prompt medical care increases the odds of a good outcome and may also save the baby’s life.