Strong Urine Smell In Babies: Causes, Symptoms And Treatment

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Urine is a clear or pale yellow, with a mild smell in most babies. However, there can be instances when you notice strong-smelling urine in babies. If your baby is well-hydrated and urine is pale, occasional strong-smelling urine is not a cause for concern. Sometimes, a strong urine odor can be due to inadequate feeding. However, it is advised to seek pediatric evaluation if your baby has persistent foul-smelling urine.

Read this post to learn about the causes, symptoms, treatment, and prevention of strong-smelling urine in babies.

Risk Factors And Causes Of Smelly Urine

The smell of a baby’s urine may change due to various factors ranging from diet to illnesses. Babies may have smelly urine due to the following reasons (1).

  • Not getting enough milk and dehydration may cause dark and strong-smelling urine due to increased concentration of urine.
  • Urinary tract infections may cause foul-smelling urine in babies. You may also look for other UTI symptoms, such as fever, since all babies with foul-smelling urine may not have UTI.

    Fever could also cause strong-smelling urine in babies

    Image: Shutterstock

  • Maternal diet may influence the smell of urine in breastfed babies. Although scientific evidence is lacking, certain foods, such as onion, asparagus, and garlic, in a mother’s diet may cause an unusual smell in the baby’s urine.
  • Maternal medications, such as antibiotics, may also cause a strong urine odor in breastfed babies.
  • Diabetes (increased blood glucose) or maple syrup urine disease may cause a sweet urine odor.
  • Liver failure may also cause smelly urine in babies. This is usually associated with jaundice (yellow skin).
Point to consider
Vitamin B6 supplements may cause clear or pale yellow urine with mild smell (1).

Dr. Sharon Wiener, a Texas-based board-certified pediatrician, says, “If your baby’s urine smells like vinegar, it is generally due to mild dehydration from not taking in fluids (breast milk) overnight. But it can also be due to something mom has eaten; for example, asparagus. If the odor is persistent and does not resolve quickly, it is always better to present it to your pediatrician to ensure it is not a urinary tract infection.”

Sometimes urine may smell different as babies grow older. Not changing nappies for a long time may also cause smelly urine. Some babies could have foul-smelling urine without any other issues. You may consult a pediatrician if you are concerned.

Symptoms And Signs That May Occur With Smelly Urine

Lethargy can indicate smelly urine

Image: Shutterstock

You may notice the following signs and symptoms of possible underlying conditions in babies with persistent smelly urine (2).

  • Foamy or cloudy urine
  • Dark urine such as bloody, tea-colored, or pink-tinged
  • Dribbling of urine
  • Oliguria or no urine
  • Fever
  • Edema
  • Symptoms of dehydration, such as sunken eyes and dry mouth
  • Weakness
  • Irritability
  • Crying
  • Lethargy

These signs may arise due to conditions that are also the reason behind smelly urine. Seek pediatric care if your baby has any of the above-listed symptoms with a strong urine smell.

Be watchful
Constipation in children may cause foul-smelling urine. The condition does not allow the bladder to empty completely. As a result, the leftover urine starts smelling (4).

Treatment For Smelly Urine

Occasional cases of smelly urine may not require any treatment. Babies with persistent strong- or foul-smelling urine should be evaluated and treated. The treatment options may vary depending on the underlying cause.

  • Rehydration therapy with intravenous (IV) or oral fluids for dehydration
  • Frequent bottle or breastfeeding suggested for maintaining hydration

    Breastfeeding can help maintain hydration

    Image: Shutterstock

  • Removal of bladder stones
  • Control of diabetes and other metabolic disorders
  • Maternal diet modifications
  • Changing maternal or infant’s medications that may cause abnormal color and smell of urine

Prevention Of Smelly Urine In Babies

Meeting the baby’s fluid requirements through feeding and fluids can dilute urine and reduce the intensity of its smell. Babies will have at least five wet diapers per day with pale or straw yellow urine if they are hydrated well. Diapers should be changed on time to prevent them from stinking. Treating and controlling underlying conditions also help to prevent foul urine odor.

Frequently Asked Questions

1. Why does a baby’s urine smell like ammonia?

Urine is composed of waste products, such as urea, dissolved in water. Urea may disintegrate into ammonia in some conditions. When it is diluted, you may not feel the smell. However, concentrated urine may have a strong odor of ammonia. The following conditions may cause ammonia odor in the urine.

An occasional ammonia smell in a baby’s urine is normal. However, if it persists, pediatricians may order tests to look for kidney or bladder issues.

2. Is smelly urine a sign of teething?

There is no direct link between teething and urine odor. You may look for signs and symptoms of other conditions that may cause strong-smelling urine in babies.

3. Why does a baby’s urine smell like poop?

If your baby’s urine smells like poop, first check for soiled diapers. Feces-smelling urine without signs of bowel movement can be due to a urinary fistula, an abnormal opening connecting the bladder to the intestines. It may cause leakage of feces into the urine, resulting in the poop smell of urine (3). Consult a doctor since it may increase the risk of urinary tract infections and require surgical correction.

4. What does my baby’s sweet-smelling urine indicate?

Dr. Wiener observes, “The most common cause in babies is the metabolic disorder, maple sugar urine disease. This is generally picked up on a baby’s neonatal screens at birth and two weeks. The disorder may cause significant issues if not caught early. Occasionally, a urinary tract infection can also cause sweet-smelling urine, although a foul odor is more typical. Glucose in the urine, indicating diabetes, a very rare condition in babies, can also cause sweet-smelling urine.”

Inadequate hydration is the usual cause of strong-smelling urine in babies. Changing diapers after long intervals can also give a foul smell to the urine. Increasing breastfeeding frequency or rehydration therapy for oral babies may resolve the problem without complications. However, some underlying conditions such as urinary tract infections, jaundice, diabetes, or maternal medications may cause a foul smell in urine. Check with a pediatrician if the condition doesn’t subside in a few days or if other symptoms such as fever, blood in urine, lethargy, or irritability are involved.

Infographic: Other Causes And Diagnostic Tests For Baby’s Smelly Urine

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causes and diagnostic tests for babys smelly urine [infographic]
Illustration: MomJunction Design Team

Key Pointers

  • Strong urine smell in babies could be due to varied reasons such as maternal medications or diet, or lack of milk.
  • No need to worry as there are treatments depending on the cause.
  • Consult a pediatrician if you notice a persistent foul smell.


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
1. Smelly Urine; National Health Service
2. Urine Odor; Healthgrades
3. Urine Odor; MedlinePlus; US National Library of Medicine
3. Why Does My Child Have Stinky Pee? Nationwide Children’s Hospital
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