Blood And Mucus In Baby's Stool: Causes & What To Do

Finding blood or mucus in your baby’s stool during a diaper change can stop you in your tracks. It is a terrifying moment for any parent, and your mind likely jumps to the worst-case scenario.

The good news is that these changes are often minor and treatable. However, noticing something out of the ordinary is an important observation that can help you catch a potential problem early.

It is always reassuring to find a cause and a solution when it comes to your little one’s health. We will walk you through the common reasons for these changes, what they look like, and when you need to pick up the phone and call the pediatrician.

Stools With Mucus

If you open a diaper and it looks like the poop is covered in slime or jelly, you are likely looking at mucus. This usually appears as shiny, stretchy strings mixed in with the regular stool.

Sometimes the explanation is simple, but other times it points to an underlying issue that needs attention.

If your baby is teething or has a cold, they are likely swallowing large amounts of saliva and nasal drainage. Because digestion moves rapidly in infants, this mucus can pass through the tract undigested and end up in the diaper.

However, breastfeeding dynamics can also play a role. Your baby might be getting too much foremilk and not enough hindmilk.

Foremilk is the thinner milk at the start of a feed, which is higher in lactose. Hindmilk is the fattier, calorie-dense milk that comes later. A lactose overload from too much foremilk can irritate the gut and cause mucus.

To prevent this, ensure your baby fully drains one breast before switching to the other. If they don’t finish, start the next feeding on that same side.

While mucus is common during the newborn stage or teething, consistent mucus can indicate food allergies or infections. If your baby seems fussy, has a fever, or isn’t eating well, save the diaper and contact your pediatrician.

Stools With Blood

Discovering blood in a diaper is alarming. While you may not want to inspect your baby’s poop closely, the color and texture of the blood provide vital clues for your doctor.

Here are the generalized descriptions of what you might see and what they usually mean.

1. Stools With Bright Red Blood

Bright red blood typically indicates active bleeding from the lower digestive tract or rectum.

• Milk protein allergy: This is a common cause. Your baby acts normal, but the immune system reacts to proteins in formula or breast milk, causing inflammation and blood-tinged mucus ⁽¹⁾.
• Anal tear (fissure): If your baby strains to pass large, hard stools, the anal opening can tear slightly. You will often see a bright red streak on the outside of the poop or spots of blood in the diaper.
• Bacterial infection: Diarrhea mixed with red blood can signal a bacterial infection like Salmonella or E. Coli. Your baby will likely act sick, feverish, or lethargic.
• Dietary causes: Sometimes, it isn’t blood at all. If your baby recently ate beets, red gelatin, or foods with red dye, the poop may look alarmingly red.
• Intestinal bleeding: In rarer cases, significant bright red blood comes from abnormalities in the lower intestines, such as polyps or Meckel’s diverticulum.

2. Stools With Blackish Blood

Blood that looks black, tarry, or like coffee grounds (melena) has usually been digested. This means the bleeding occurred higher up in the digestive tract.

• Swallowed maternal blood: If you are breastfeeding and have cracked or bleeding nipples, your baby may swallow your blood. It poses no harm to the baby but looks scary in the diaper as black specks.
• Upper GI bleeding: Rarely, black stool indicates bleeding from the baby’s stomach or upper small intestine due to severe reflux, gastritis, or malformation.

When in doubt, take a picture or save the diaper. Your doctor can run a simple test to confirm if the substance is actually blood.

Reasons Blood Or Mucus Appear

Many causes for blood or mucus are benign, but some require immediate medical intervention. Understanding the potential triggers helps you gauge the urgency of the situation ⁽²⁾.

Here are specific conditions associated with these symptoms:

• Infectious gastroenteritis: Viruses, bacteria, or parasites can inflame the intestines. Alongside blood or mucus, you will typically see vomiting, diarrhea, and fever.
• Anal fissures: These tiny tears in the anal lining are painful. You might see your baby grimace or cry while pooping. Treatment usually involves treating the underlying constipation ⁽³⁾.
• Allergic Colitis: This condition occurs when a baby’s immune system overreacts to proteins, most commonly cow’s milk or soy. It causes ulcerations in the colon lining. If you are breastfeeding, your doctor may ask you to eliminate dairy from your diet.
• Intussusception: This is a medical emergency where one part of the intestine telescopes into another, creating a blockage. It presents with “currant jelly” stools (blood and mucus mixed) and severe, intermittent abdominal pain.

  Intussusception is traditionally thought of as abdominal pain associated with “currant jelly stool,” in which the stool looks like red currant jelly.

  

  Editor's Note:

  Dr. Gina Jansheski, MD, FAAP
• Necrotizing Enterocolitis (NEC): This is a serious condition mostly affecting premature infants where the intestinal tissue becomes inflamed and dies. It causes bloody stools, a swollen belly, and feeding intolerance.
• Vitamin K deficiency: Newborns receive a Vitamin K shot at birth to help blood clot. Without it, babies can suffer from Vitamin K Deficiency Bleeding (VKDB), which can cause spontaneous bleeding in the stool ⁽⁴⁾.
• Supplements and medications: Iron supplements can turn stool dark green or black, which parents often mistake for old blood. Certain antibiotics can also irritate the stomach or cause mucus.

Is This An Emergency?

Knowing when to act is the most important part of managing your baby’s health.

If you find a small amount of blood or mucus but your baby is smiling, playing, and feeding well, it is likely not an emergency. However, you should still call your pediatrician during office hours to keep them informed and rule out allergies.

You need to seek immediate care if the blood or mucus is accompanied by:

• Refusal to eat or drink.
• Signs of dehydration (no wet diapers for 6+ hours, dry mouth).
• Fever (over 100.4°F or 38°C in babies under 3 months).
• Vomiting (especially if it is green or bloody).
• Inconsolable crying or signs of abdominal pain.
• Large amounts of blood in the diaper.

FAQs

Can Overfeeding A Baby Cause Blood In Stool?

Overfeeding itself rarely causes blood in the stool. However, it can overload the digestive system, leading to forceful spit-ups or rapid digestion. If you see blood, it is more likely due to a secondary issue like a milk protein allergy or a small anal tear from straining.

Can A Virus Cause Bloody Mucus In Stool?

Yes, viral infections like rotavirus can inflame the intestinal lining, leading to bloody mucus. If your baby has diarrhea, vomiting, or a fever alongside these stools, contact your pediatrician to manage hydration and monitor the infection.

Can Lactose Intolerance Cause Blood In Stool?

True lactose intolerance is rare in babies and typically causes gas, bloating, and watery diarrhea, not blood. Blood in the stool is more commonly a sign of Cow’s Milk Protein Allergy (CMPA), which involves the immune system rather than enzyme digestion.

What Can Be Mistaken For Blood In Stool?

Foods like beets, red peppers, tomatoes, and red gelatin can dye the stool red. Additionally, uric acid crystals in a newborn’s diaper can look like orange-red dust, which is often harmless but should be checked if it persists.

How Much Blood In Stool Is Normal?

Technically, no amount of blood in the stool is “normal,” but small amounts from an anal fissure or temporary allergy are common and often not dangerous. You should always report any amount of blood to your doctor to ensure it isn’t a sign of a larger problem.

Can Teething Cause Mucus In Stool?

Yes, teething often causes excess drool. Since babies swallow this saliva, it can irritate the intestines and result in loose, mucus-filled stools. This is usually accompanied by other teething signs like gnawing on hands and irritability.

Why Is My Baby’s Mucus Green?

Green mucus typically indicates that food is moving through the baby’s digestive tract very quickly (rapid transit). It can be caused by a foremilk/hindmilk imbalance, a virus, sensitivity to a new food, or simply the iron in baby formula.

The Bottom Line

Seeing blood or mucus in your baby’s diaper is stressful, but you are not alone. While it is not “normal,” there is usually a straightforward explanation, such as a small tear, a dietary sensitivity, or a mild virus.

Your pediatrician is your best resource here. They can run simple tests to pinpoint the cause and guide you toward the right solution.

Trust your parental instincts. If your baby looks sick, acts differently, or seems to be in pain, seek medical attention immediately. It is always better to get checked out and find nothing than to wait at home and worry.