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

Medically Reviewed by Dr. Gina Jansheski, MD, FAAP
Learn how to tell if your baby’s stool is normal or something to call the doctor about.

Have you ever noticed blood or mucus in your baby’s stool during a diaper change? Are you worried there could be something seriously wrong?

Often, your worries will be just that — worries. However, there may be times when you will notice something out of the ordinary and can catch a problem early before it becomes a serious issue.

When it comes to your concerns about your baby’s health, it is always reassuring to find a cause and a solution. And if you notice blood or mucus in your baby’s stool, it’s natural to want to figure out why it’s there.

Key Takeaways

  • Mucus in baby’s stool can be due to drooling, teething, breastfeeding, or respiratory infection; usually harmless, but consult a doctor if baby appears ill or not feeding well.
  • Bright red blood in stool could result from milk protein allergy, anal tear, bacterial infection, diet, or intestinal bleeding; blackish blood may indicate blood from breastfeeding mother’s nipples or upper digestive tract bleeding.
  • Serious causes of blood or mucus in stool include infection, anal fissures, digestive tract/colon issues, intussusception, colitis, and breastfeeding with cracked or bleeding nipples.
  • If baby is feeding normally and seems happy, call a doctor; if baby appears ill or not feeding well, visit a doctor or emergency room immediately, and save the diaper or take a photo for reference.

Stools With Mucus

If your baby’s diaper looks like it’s covered in slime, that is probably mucus. Stool that is any color with shiny, stretchy strings in it means mucus is present.

Sometimes there can be a very simple explanation for this, or there can be other underlying issues.

If your baby is exceptionally drooly or has a runny nose, what you found in the stool could have come from undigested mucus from the saliva or nasal passages. Things can move very rapidly through your baby’s digestive tract, especially when they are breastfed.

Another thing to think about if you are breastfeeding your baby is that your baby may be getting too much foremilk and not enough hindmilk.

The foremilk has less fat and more lactose in it. It provides carbs, proteins, and vitamins. Hindmilk is much higher in fat and has more calories. Your baby needs both foremilk and hindmilk to grow.

A lack of hindmilk can cause your baby’s stools to contain mucus. To prevent this, make sure your baby is entirely emptying your breast during a feeding. If this doesn’t happen, begin your next feed on the same breast you finished your last feed with.

It is not uncommon to see mucus in a baby’s stools during the first few weeks of life, then later with drooling and teething. Mucus is also common in breastfed babies’ stools or babies with a respiratory tract infection with lots of nasal discharge. The presence of mucus is usually harmless, but it can sometimes indicate something more, like an infection or food allergy. So if your baby seems ill, is not feeding well, or has other signs along with mucus in the stools, save the diaper, and call your baby’s doctor for advice.

Stools With Blood

It can be alarming to find blood in your baby’s stools. The last thing you want to do is closely examine your baby’s poop, but it can give you some very important hints about what might be going on and help you get to the answer. Here are some very generalized descriptions of the things you might see.

1. Stools With Bright Red Blood

These are some of the reasons your baby’s stools may have bright red blood in them.

  • Milk protein allergy: Your baby’s poop may appear normal but have blood-tinged mucus (1). Your baby will likely look fine.
  • Anal tear: If your baby is straining to poop and passes large, hard stools with slight amounts of red blood, this could be the result of an anal tear. It usually appears as a streak of blood clinging to the outside of the hard poop or as little bright red spots in the diaper.
  • Bacterial infection: If your baby is feeling unwell and has diarrhea mixed with red blood, they may have a bacterial infection.
  • Diet: If you notice more significant amounts of bright red blood in the diaper but your baby looks otherwise well, consider their recent diet. You could be seeing the effects of baby beet juice, red jello, or something with red food coloring (which is not recommended) rather than blood.
  • Intestinal bleeding: Larger amounts of bright red blood may also be from a digestive system abnormality, causing bleeding from the lower part of the intestines.

2. Stools With Blackish Blood

If you notice blood in your baby’s stool that looks almost black, this usually means it is blood from a little higher in the intestinal tract that has been digested.

  • Blood from nipples: You might think it a little strange, but if you are breastfeeding, there could be a simple answer. Cracked or bleeding nipples can cause your baby to digest blood from your body. This will often appear like black seeds or specks inside the poop. And it will typically be seen in the first few weeks after birth when you both are adjusting to breastfeeding life.
  • Other bleeding: There are rare cases where black blood in the stool can result from some bleeding from the upper digestive tract due to an intestinal abnormality or malformation. This type of bleeding usually happens in larger amounts and more frequently.

It’s always best to be safe rather than sorry, so when you come across any of these, or if you are concerned at all, reach out to your baby’s doctor for more insight.

Reasons Blood Or Mucus Appear

There can be many different reasons for blood or mucus in your baby’s stool, and most of them aren’t too serious. However, there are a few causes that pose a higher threat than others and give you the feeling that something is not quite right (2).

  • Infection: The blood or mucus could result from an intestinal infection like Salmonella, Shigella, or E. Coli. In this case, you would see that your baby is ill and not feeding well. Other signs you would see are diarrhea, fever, and vomiting.
  • Anal fissures: Blood could be present in your baby’s stools if there is a tiny tear in the lining of the anus. This area is very delicate in babies and can tear with the passing of a large, hard stool. You may not even notice it until you look very closely at the area between the little folds of the anal opening (3).
  • Digestive tract/colon issues: If the blood seems to be continuous, or if there is a significant amount, there is more likely to be an issue with the digestive tract or colon. Occasionally, during development, something can be a little out of whack when the intestinal tract is forming. The first sign of this could be bleeding. Sometimes there is a family background of the disorder, or the baby has had an associated problem such as long-term, severe constipation, or has a chronic disease (4).
  • Intussusception: This is when one portion of the intestine inverts into another. It usually begins with sudden loud bursts of crying and abdominal pain in repeated episodes lasting 15 to 30 minutes with periods of improvement between them. It is a serious situation that requires immediate medical attention.
    Intussusception is traditionally thought of as abdominal pain associated with “currant jelly stool,” in which the stool looks like red currant jelly.
    Headshot of Dr. Gina Jansheski, MD, FAAP

    Editor's Note:

    Dr. Gina Jansheski, MD, FAAP
  • Colitis: Allergic colitis is when your baby’s immune system overreacts to certain proteins causing inflammation and ulcerations to occur in the lining of the colon. The number one cause of this in infants is cow’s milk protein. It can be from the formula or even from your diet if you are breastfeeding.
  • Breastfeeding: If you are breastfeeding and have a bleeding or cracked nipple, your baby may ingest blood, which appears later in the stools. This is harmless for your baby, even though it is painful for you!
  • Iron supplement: Generally, this is not an issue with very young babies, but it is good to know that taking iron can sometimes cause the poop to be dark green to blackish.

Is This an Emergency?

Blood or mucus in the stools can be alarming, and it is good to what might be causing it.

If you notice blood or mucus in the stools, but your baby is feeding normally and acting happy as usual, it’s a good idea to give your baby’s doctor a call to inform them and see if they want to take further action.

If there is blood or mucus and your baby is not feeding well or looking ill, it is best to get in right away with your baby’s doctor or visit the emergency room for an evaluation.

Don't Panic

It can be scary to know there could be something wrong with your baby, but try to stay calm. If you have to visit the emergency room, reach out to a friend or family member so you don’t have to endure it alone. A little bit of support can go a long way.


Can Overfeeding a Baby Cause Blood In Stool?

Overfeeding itself isn’t likely to cause blood in a baby’s stool. But it can result in digestive problems like spit-ups or mild diarrhea.

If you notice blood, call your doctor immediately, as it could be a sign of an allergy or a minor tear in the anus from passing a hard stool.

Can a Virus Cause Bloody Mucus In Stool?

Absolutely, certain viral infections, like a rotavirus infection, can lead to bloody mucus in your baby’s stool. If you notice this alongside other symptoms like vomiting or a high fever, a pediatrician’s visit is in order.

Can Lactose Intolerance Cause Blood In Stool?

Lactose intolerance often leads to digestive problems, but it typically doesn’t cause blood in the stool. If you notice blood, consult with your pediatrician to rule out conditions like a milk protein allergy.

What Can Be Mistaken for Blood In Stool?

You may mistake some foods, like beets or red jello, or certain medications and supplements for blood in the stool. If you’re ever in doubt, it’s best to save the questionable diaper and bring it to your pediatrician for testing.

How Much Blood In Stool Is Normal?

Any blood in your baby’s stool warrants a call to your healthcare provider. While it can be a common sign of a minor issue, it’s always best to get it checked to rule out anything more serious.

The Bottom Line

Finding blood or mucus in your baby’s stool is a cause for concern. Even though there may be a simple explanation, it is not normal for blood or mucus to appear in the stools, so there could be something going on that isn’t quite right. Your baby’s doctor should be able to diagnose the problem and help you figure out what your next steps should be.

If your baby is not feeding well, has a fever, or seems to be in pain, you should seek medical attention immediately to see whether or not there is a serious problem.

Save The Diaper

Always save a sample diaper to bring in to your medical professional. If you cannot do that, take a photo with your phone. It always helps if your doctor can see what’s going on rather than figure things out based on a description.
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Headshot of Dr. Gina Jansheski, MD, FAAP

Medically Reviewed by

Dr. Gina Jansheski, MD, FAAP

Dr. Gina Jansheski is a board-certified pediatrician with over 20 years of experience treating infants and children of all ages in many different settings. Dr. Jansheski is the mother to three sons, has sponsored a young girl in India for the past 7 years and has also devoted her time to a new charity that she founded, Helping Hands M.D. feeding street animals in Thailand and India.