Is sweet-smelling baby poop normal?

Breastfed babies have mild, sometimes slightly sweet-smelling poop - this is completely normal. But if your baby's poop suddenly develops a distinctly sweet or fruity smell (especially paired with other symptoms), this can indicate a serious condition called maple syrup urine disease or diabetic ketoacidosis. The key is change from baseline.

Why would baby poop smell sweet?

Normal sweet smell: breastfed babies have naturally mild-smelling poop sometimes described as sweet or yogurt-like. Concerning sweet smell: certain metabolic conditions (maple syrup urine disease, isovaleric acidemia) produce a sweet or fruity odor. This is rare but serious.

Is sweet poop a sign of diabetes in babies?

Babies don't typically get type 2 diabetes. Type 1 diabetes can develop in infants but is very rare. If a baby enters diabetic ketoacidosis (very advanced diabetes), poop/breath can have a sweet fruity smell. But this is paired with severe symptoms: extreme lethargy, fast breathing, vomiting. Not just poop smell.

What is maple syrup urine disease?

MSUD is a rare genetic metabolic disorder where baby's body can't break down certain amino acids. The result: sweet or maple syrup-smelling poop and urine. It's detected in newborn screening. If your baby has a distinctly sweet smell and you haven't had newborn screening, this is worth asking your pediatrician about.

When should I call my doctor about sweet-smelling poop?

One instance of mildly sweet poop in a breastfed baby: not urgent. Distinctly sweet, fruity smell that's new or unusual, paired with lethargy, poor feeding, or vomiting: call your pediatrician today. New sweet smell in an older baby: mention at next visit. When in doubt, call.

Sweet-Smelling Baby Poop: Normal or a Warning...

Your baby's poop smells... sweet? Not bad - actually sweet. Is this normal? Should you be concerned?

The answer depends on your baby's baseline and whether this smell came with other changes. Let's break this down.

Normal Sweet-Smelling Poop

Breastfed Babies

Breastfed babies have naturally mild-smelling poop, and some parents describe it as slightly sweet - sometimes compared to yogurt, mild cheese, or a mixture of sweet and tangy. This is completely normal.

Why: Breast milk is completely absorbed, and the minimal waste that passes through produces very mild odors. There's very little fermentation happening because there's very little material.

Certain Foods

Once solids start, foods can change poop smell in ways that might seem sweet:

Fruits (especially bananas, peaches, apricots, sweet potatoes)
Sweet potato and squash
Yogurt
Honey (though not before 12 months due to botulism risk)

If your baby ate sweet foods and poop smells slightly sweet, this is normal digestion.

When Sweet Smell Is a Concern

Distinctly Sweet or Fruity Smell

If baby's poop (or urine) develops a distinctly sweet or fruity smell that's different from their normal baseline, this warrants attention. This can indicate a metabolic disorder. The rare conditions that produce this are:

Maple Syrup Urine Disease (MSUD)

What it is: A genetic metabolic disorder where baby's body can't break down certain amino acids (branched-chain amino acids). These build up and produce a sweet or maple syrup smell in poop, urine, and sometimes even sweat.

How common: Very rare - about 1 in 200,000 babies.

When it appears: Usually within the first week of life, though it can develop later. Newborn screening tests catch MSUD.

Other symptoms: Along with the sweet smell, affected babies have poor feeding, lethargy, seizures, and a distinctive musty sweet smell. These symptoms develop if not treated.

What to do: If you didn't receive newborn screening results or they were unclear, and your baby has a distinctly sweet-smelling diaper plus any of these symptoms, call your pediatrician immediately.

Isovaleric Acidemia

What it is: Another rare genetic metabolic disorder producing a distinctive "cheesy" or "sweaty feet" smell, sometimes described as sweet.

How common: Very rare - about 1 in 250,000 babies.

When it appears: Usually in the first few weeks of life.

Other symptoms: Poor feeding, vomiting, lethargy, seizures.

Diabetic Ketoacidosis

What it is: When diabetes is very advanced and untreated, the body breaks down fat too quickly, producing ketones. Poop and breath can smell sweet or fruity.

How common in babies: Extremely rare. Type 1 diabetes in infants is uncommon, and diabetic ketoacidosis only happens if diabetes is undiagnosed and untreated.

Other symptoms: Severe lethargy, fast breathing (baby taking many breaths per minute), vomiting, extreme fussiness.

What to do: If you see these symptoms plus sweet-smelling poop, go to the ER immediately.

The Newborn Screening Factor

In the US, all newborns receive screening for metabolic disorders including MSUD and isovaleric acidemia. This screening catches affected babies early when treatment can prevent serious problems.

If your baby had normal newborn screening and now at 2-3 months has sweet-smelling poop but is otherwise well, this is very unlikely to be a metabolic disorder. But if you're concerned, mention it to your pediatrician at the next visit.

The Decision Tree

Breastfed Baby with Mildly Sweet Poop + Acting Well

Probably normal. Nothing to do.

Baby on Solids with Sweet Poop After Eating Sweet Foods

Probably from the food. Nothing to do.

Distinctly Sweet or Fruity Smell, Different from Baby's Baseline

Worth mentioning at next pediatrician visit. If baby also has poor feeding, lethargy, or vomiting, call the same day.

Sweet Smell + Poor Feeding, Lethargy, Vomiting, or Seizures

Call your pediatrician or go to the ER. These are urgent symptoms regardless of poop smell.

Don't Panic, But Do Pay Attention

Sweet-smelling poop in a breastfed baby who's feeding well and acting normally is almost certainly nothing. But if the smell is distinctly sweet (not just mildly sweet), and it's new, and your baby has newborn screening done, mention it. Your pediatrician can confirm everything is fine or investigate further if needed.

Track the Change

The key to detecting abnormal smell is knowing what normal smells like for YOUR baby. PipPoopie lets you log smell with each diaper, so you have a baseline and can notice when something actually changes instead of second-guessing your memory about what normal is.