Black Lines In Baby Poop (Causes, Symptoms & Solutions)

Babies poop frequently, so it’s not uncommon for food not to be fully processed given that their digestive tract is still maturing and certain foods like bananas may be more difficult for them to process, resulting in black strings or worm-like pieces in their poop from the undigested food.

As a parent, especially a new parent, all the questions and jitters that pop up when you see black lines in your child’s poopy diaper can be unsettling. 

Is my baby sick? Is this bad? Did I feed them something dangerous? Do we need to go to the doctor? And many more.

Are black lines in baby poop something to worry about?

No. The black lines in a baby’s poop are common, and nothing to worry about since almost all children will have it at some point in their early months, but it’s most likely to happen in the first few weeks of birth.

The primary cause of this is the undigested food, in this case, the milk, because the little ones have only started feeding through their digestive tract after birth, and their stomach lining and intestines are still getting used to processing nutrients that are not fed directly to them via the umbilical cord.

These black lines normally go away from the baby’s poop on their own after a few short weeks.

Major causes the black lines in a baby’s poop

Several common sources that are not a cause of concern for black lines in a baby’s poop include:

Undigested food

A common cause of black lines in a baby’s poop is the fiber from bananas and other fiber-rich foods. Though they are not harmful, it would be best to reduce consumption so their little system doesn’t have to work harder.

Once they are old enough for finger foods, bananas make a great option, so just cut back but don’t cut out their daily intake.


Black lines in a baby’s poop can be caused by mucus and are nothing to worry about if the baby is still very young. These are mucus that needs to be passed through that is leftover from when the baby was still in the womb.

Unlike nasal mucus, this is black because it is mixed with the toxins expelled during normal bowel movements.

Strings, hairs, and other swallowed objects

If the baby is of crawling age, there’s a possibility of the black lines in their poop being swallowed objects of some kind, and the body doesn’t digest them, and they come out through the other end.

Remember, children put just about anything they can get their hands on in their mouths. If it’s a string or hair, only pull it gently or leave it if it hasn’t been pushed through the digestive tract as you don’t want to be causing any pressure in there.


Meconium is the substance that lines the baby’s stomach during pregnancy and is usually released over the first few days to weeks after birth.

It helps to protect the baby’s sensitive intestines while they are forming, and seeing it pass in the little one’s stool only means that their tiny bodies are adjusting to the outside world.

When to worry about the black lines in your baby’s poop

The list of when to worry about black lines in your baby’s poop is very short, but we shall cover it just to put the overactive parent’s minds to rest.

The two big factors to consider if you are dealing with black lines in your baby’s poop are:

  1. Excessive quantities of string or hair – While bits and pieces here and there of strings and hair are grosser than concerning, a lot of it is a different matter since not even an adult’s digestive system can process hair. If that’s the case, give it about a day to pass through and pay close attention to the baby’s bowel movement. If it appears slow, painful, or even stops entirely, then you should seek professional help. 
  2. If the black lines in the poop are accompanied by other symptomsA food allergy may cause some change in your baby’s poop but is usually accompanied by fever, running nose, and sometimes some traces of blood in the poop as well and this may cause inflammation and a stronger diaper rash may appear. If you think your baby is dealing with an allergy or food intolerance and displaying severe allergic symptoms such as trouble breathing, bring them to the hospital immediately.


What do worms in baby poop look like?

You can spot worms in your baby’s poop, and you might also see them in your baby’s bottom. They look like pieces of white thread, and they usually come out at night while your child is sleeping.

The symptoms can be extreme itching and irritability around the anus, particularly at night, wetting the bed, and waking up frequently.

You can buy mebendazole from the pharmacy in tablets or liquid form and treat everyone in your household even if they don’t have symptoms.

How do babies get black worms?

Ascariasis is the most common human infection globally. The Ascaris eggs are found in soil, and human feces, and they get into the body when someone eats or drinks something contaminated with the eggs.

Most babies with the worms got it by putting dirty hands in their mouths or eating fruits and vegetables that weren’t peeled, washed, or cooked.

Take away

After introducing solid food to babies’ diets, there will be noticeable changes in their poop which can be a little worrying, particularly if you’ve become accustomed to the pure yellow, almost sweet-smelling poop of your breastfed baby.

These changes may be in the form of black lines in a baby’s poop, which can be concerning at first, but now that we know it isn’t a big problem, we can relax and enjoy the amazing and precious little antics they learn and how they grow so quickly.

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Hello, I am Emelda from Nairobi, Kenya. They simply call me mama Lilly. A fun of long road trips and a very good cook, along with my mommy duties to a super active girl. She inspires and challenges me in equal measure, and that is how I get to share with you our journey of triumph as we grow and tag you along.

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