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Blood In Baby’s Poop- Is It A Milk Allergy?

You’re panicking, right? You found blood in your baby’s poop and you’re panicking.

Okay, take a deep breath.

Blood in baby’s stool usually isn’t a serious issue, however it is definitely something to be concerned about. You need to figure out the cause and speak with your Pediatrician.

Read: A Guide To The Most Common Breastfeeding Problems

I still, however, recommend being knowledgeable on the subject, especially if you are breastfeeding. Pediatricians aren’t always very informed when it comes to breastfeeding problems.

When my first child was a few weeks old, I noticed a little blood in her diaper. I called the Pediatrician and stupidly said, “There is a little blood in my baby’s diaper”.

I was told that a little blood in newborn stool was normal. That it was brick dust (which is Urate crystals often found in a breastfed baby’s URINE. Not stool. I unfortunately left this important detail out.)

Then it happened again. I was again told that it was normal, even though I was  really starting to panic.

Then, at the age of 6 weeks, I again saw blood in my infant’s stool. And this time it was A LOT.

Finally my doctor realized what i was trying to say so that I could start treating my baby.

She ended up having a milk allergy, but there are other causes of blood in baby poop.

Read more about signs of dairy allergy in babies or see all of the posts that I have written about babies with milk protein allergy.

Causes Of Blood In Baby Poop

Finding blood in baby's poop can be alarming. Learn the causes and treatment of blood in baby stool.

Blood In Baby Stool And Constipation

As everything is new to our babies, so is pooping. It can be uncomfortable for our babies, and sometimes painful, especially if your baby is constipated.

Constipation can cause anal fissures or tears, which can’t always be seen. This is the most common cause of blood in baby poop. The blood will look like a streak on the outside of the baby’s stool.

If your baby is suffering from constipation, a change in diet might be helpful.

Blood In Breastfed Baby Stool

Cracked Nipples

If you are breastfeeding and have cracked, bleeding nipples, the blood in your baby’s diaper is likely blood that your baby has ingested.

While this is harmless to your baby, it is important that you find a way to heal yourself.

See my breastfeeding tips for pain, which will tell you the best methods for breastfeeding nipple pain relief.

Your Baby Has A Food Allergy

While most babies don’t have an issue with the diet of their breastfeeding mother, that’s not always the case. It WAS the case with both of my babies.

The most common food allergy found in babies is an allergy to milk and soy.

If your baby has blood in stool and any of the following symptoms, a food allergy is likely the cause:

  • Excessive spitting up
  • GERD or Acid Reflux
  • Symptoms of colic and/or excessive crying
  • Green stools with blood and mucus in stool
  • Eczema, rashes and/or hives
  • Excessive gassiness
  • Red, itchy eyes
  • Wheezing, congestion, etc

In order to treat a milk allergy, a breastfeeding mom will need to completely eliminate all forms of dairy and soy from her diet. For a formula fed baby, you will need to switch to a hydrolyzed formula or an amino-acid based formula.

You can read more about my experience and how to get started with MSPI.


Occasionally, oversupply can cause irritation to your baby’s system, resulting in blood in baby’s poop.

Oversupply simply means that you are producing too much milk. When you produce too much milk, your baby gets too much watery foremilk and not enough fatty hindmilk.

You may have oversupply if:

  • Baby frequently chokes and unlatches, especially at the beginning of a feed
  • Breast Milk sprays forcefully after baby unlatches
  • Baby spits up often
  • Baby is very gassy
  • You are frequently engorged

In order to treat oversupply and get your milk supply under control, you should give block feeding a try. Block feeding is simply feeding from one side for a specific amount of time (one feed, two feeds, etc).

After Starting Vitamin Or Fluoride Drops

If you recently started giving your baby vitamin or fluoride drops, they could be causing blood in your baby’s stool. Discontinue use to see if it helps.

An Intestinal Infection

If your baby’s blood in stool is accompanied by diarrhea, fever and vomiting, your baby might have an intestinal infection caused by the Rotavirus, Salmonella or E. Coli.

In this case, please make sure to take your baby to your Pediatrician as soon as possible.

Other More Serious Issues Such As Intestinal Disorders, Intussusception Or Colitis

While very rare, there are other serious issues that could be going on with your baby. Please follow up with your child’s doctor in order to rule out any of these more serious conditions.

Blood In Baby’s Stool And Teething

As I was researching in order to write this post, I came across a bunch of different moms asking if teething can cause blood in stool.

I was unable to find any medical information on this topic. However, teething can cause green, mucous stools because of the increase in saliva that your baby is swallowing. This saliva can irritate your baby’s intestines. So is it possible that teething could cause blood in stool?

I’m not a medical expert, but enough irritation (in my inexperienced opinion) could maybe, possibly cause a little bleeding.

When my first child was teething, she would get crazy gassy. So gassy that she would scream and scream at night until she passed it, and then a couple hours later the scenario would repeat again. This happened every single time, without fail, that she was teething.

Yet try to find a doctor or a medical journal that says that excess gas is a symptom of teething. You won’t. Believe me, I tried.

So I’d say anything is possible.

What to do if your baby has blood in his poop

Be prepared to tell your doctor whether the blood is throughout the poop, in one spot or if it looks like a streak.

Also be prepared to tell your doctor the color of the blood:

  • If the blood is bright red or dark maroon, it indicates a problem with your baby’s digestive tract.
  • Diarrhea and red blood indicates a bacterial infection.
  • Hard stool with a slight streak of blood indicates an anal tear.
  • Blood throughout the stool that is not bright red but not dark either indicates a food allergy.
  • Blackish blood is likely digested blood from a breastfeeding mom’s cracked nipples.

Finally, consider saving a sample of your baby’s stool, as your doctor’s office can test it to make sure that it is blood.

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Tuesday 12th of November 2019

Thank you for all this information! My 6 week old baby was recently diagnosed with CMPA, but I’ve never seen any blood visible in her poop. They tested her diapers and the results came back with blood. Is it always a large enough amount that you would see the blood in her diaper? Also, how long does it take to see an improvement in her temperament? I haven’t had dairy in about 8 days but she is still super fussy, gassy, extremely constipated and irritable. Thanks!


Tuesday 26th of November 2019

It definitely doesn't have to be visible! Dairy takes a LONG time to get out of your system, and then out of your baby's. However, I would think that you should see a difference after 8 days. Have you cut hidden dairy as well?