Physical Development

Baby or Toddler Body Odor - When Is It Normal?

Medically reviewed by Dr. Sarah Chen, MD, FAAP · Board-Certified Pediatrician

Content reviewed against published AAP, NIH, NIH guidelines

Editorial policy

Last reviewed:

Your baby's physical development is unique, and concerns about baby or toddler body odor - when is it normal, here is what you need to know.

The short answer

Babies and toddlers can develop body odor from several benign causes: sour milk caught in skin folds, sweating, diaper area odor, strong-smelling foods in the diet, and certain medications or vitamins. True body odor (like adult BO from apocrine glands) should not occur before puberty. If your baby or young toddler has a persistent unusual body odor that is not explained by skin folds, diaper, or diet, it could indicate a metabolic condition, infection, or foreign body (especially in the nose or vaginal area). Unusual persistent odor warrants a doctor visit.

Key takeaways

  • Babies and toddlers can develop body odor from several benign causes: sour milk caught in skin folds, sweating, diaper area odor, strong-smelling foods in the diet, and certain medications or vitamins. True body odor (like adult BO from apocrine glands) should not occur before puberty. If your baby or young toddler has a persistent unusual body odor that is not explained by skin folds, diaper, or diet, it could indicate a metabolic condition, infection, or foreign body (especially in the nose or vaginal area). Unusual persistent odor warrants a doctor visit.
  • Usually normal when: Sour smell from milk in skin folds or spit-up residue - resolved by cleaning
  • Call your doctor if: A newborn with a sweet, unusual smell and poor feeding or lethargy - possible metabolic emergency
  • Varies by age — see the age-by-age breakdown below
“Supervised tummy time is recommended daily from the time the baby comes home from the hospital to help prevent flat head syndrome and to strengthen neck and shoulder muscles.”
— Back to Sleep, Tummy to Play, American Academy of Pediatrics (AAP)

This is one of the most common questions parents ask. Searching for answers means you care.

What Parents Should Know

According to AAP, NIH guidelines, babies and toddlers can develop body odor from several benign causes: sour milk caught in skin folds, sweating, diaper area odor, strong-smelling foods in the diet, and certain medications or vitamins. True body odor (like adult BO from apocrine glands) should not occur before puberty. If your baby or young toddler has a persistent unusual body odor that is not explained by skin folds, diaper, or diet, it could indicate a metabolic condition, infection, or foreign body (especially in the nose or vaginal area). Unusual persistent odor warrants a doctor visit. At 0-6 months, young babies can smell sour from milk pooling in neck folds, behind ears, and in skin creases. Spit-up residue on clothing and skin also creates a sour smell. This is resolved by cleaning skin folds daily and changing clothes when soiled. A sweet or unusual smell from a newborn could indicate a metabolic disorder - maple syrup urine disease, for example, causes a distinctive sweet smell. If your newborn has an unusual smell along with poor feeding or lethargy, seek immediate evaluation. It is generally considered normal when sour smell from milk in skin folds or spit-up residue - resolved by cleaning. However, you should contact your pediatrician promptly if a newborn with a sweet, unusual smell and poor feeding or lethargy - possible metabolic emergency.

Sources: [1], [2], [3]

Normal vs. Concerning

Usually Normal
Worth Discussing
Sour smell from milk in skin folds or spit-up residue - resolved by cleaning
A newborn with a sweet, unusual smell and poor feeding or lethargy - possible metabolic emergency
Foot odor from non-breathable shoes or socks
Foul body odor with fever, skin changes, or your child seeming unwell
Temporary body odor changes after eating strong-smelling foods
Signs of early puberty (body odor, body hair, breast development) in a child under age 7-8
Diaper area smell from a soiled or wet diaper
Persistent unusual body odor that does not resolve with bathing and cleaning

By Age

What to expect by age

0-6 months

Young babies can smell sour from milk pooling in neck folds, behind ears, and in skin creases. Spit-up residue on clothing and skin also creates a sour smell. This is resolved by cleaning skin folds daily and changing clothes when soiled. A sweet or unusual smell from a newborn could indicate a metabolic disorder - maple syrup urine disease, for example, causes a distinctive sweet smell. If your newborn has an unusual smell along with poor feeding or lethargy, seek immediate evaluation.

6-12 months

As solids are introduced, babies may develop different body odors from their diet. Garlic, onion, and spices in food can cause temporary changes in sweat and urine smell. Strong-smelling feet can develop from shoes or socks that do not breathe. A fishy or foul smell from the diaper area could indicate a urinary tract infection. Clean skin folds regularly and ensure the diaper area is kept dry. If the smell persists after cleaning, it warrants investigation.

12-24 months

Toddlers are active and may sweat more, but they should not have true body odor. If your toddler has a persistent bad smell from one nostril, they very likely have something stuck in their nose (a common toddler phenomenon) - this causes a one-sided foul-smelling discharge. A persistent vaginal odor in toddler girls can also indicate a foreign body. Foul breath that is not from food may indicate a sinus infection, dental issue, or nasal foreign body.

2-3 years

True axillary (armpit) body odor before age 8 is unusual and could indicate premature adrenarche (early activation of adrenal glands). If your toddler has genuine adult-like body odor from the armpits, mention it to your pediatrician. They may check for signs of early puberty. Other causes of unusual odor in this age group include: fungal skin infections, certain medications, and rarely, metabolic conditions. Most odor complaints at this age have a simple, benign explanation.

What to Tell Your Pediatrician

  • Describe when you first noticed baby or toddler body odor - when is it normal and how it has changed over time.
  • Note your baby's current age and which age-specific patterns you are seeing.
  • Mention if persistent unusual body odor that does not resolve with bathing and cleaning.
  • Mention if adult-like armpit body odor in a child under 8.
  • Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
  • Bring a list of any questions or observations you want to discuss at the appointment.

What Should You Do?

When to take action

Probably normal when...
  • Sour smell from milk in skin folds or spit-up residue - resolved by cleaning
  • Foot odor from non-breathable shoes or socks
  • Temporary body odor changes after eating strong-smelling foods
  • Diaper area smell from a soiled or wet diaper
Mention at your next visit when...
  • Persistent unusual body odor that does not resolve with bathing and cleaning
  • Adult-like armpit body odor in a child under 8
  • Foul smell from one nostril (likely nasal foreign body)
  • Persistent foul odor from the vaginal or genital area
Act now when...
  • A newborn with a sweet, unusual smell and poor feeding or lethargy - possible metabolic emergency
  • Foul body odor with fever, skin changes, or your child seeming unwell
  • Signs of early puberty (body odor, body hair, breast development) in a child under age 7-8

What You Can Do at Home

  • Keep track of when you notice baby or toddler body odor - when is it normal — noting the time of day, duration, and any triggers can help your pediatrician.
  • Remember that sour smell from milk in skin folds or spit-up residue - resolved by cleaning — this is generally within the range of normal.
  • At 0-6 months, focus on observation rather than intervention unless your pediatrician advises otherwise.
  • Provide plenty of supervised floor time and tummy time to support your baby's physical development.
  • While monitoring at home, seek immediate care if a newborn with a sweet, unusual smell and poor feeding or lethargy - possible metabolic emergency.

Baby Sweating a Lot - Excessive Sweating

Sweating in babies is common, especially on the head, because babies have a high density of sweat glands on their scalp and their temperature regulation is still developing. Sweating during feeding, sleeping, and crying is usually normal. However, excessive sweating during feeds (especially if the baby also breathes fast or tires easily while eating) can occasionally indicate a heart condition. If your baby sweats heavily with feeds AND has poor weight gain or breathing difficulties, mention it to your pediatrician.

Baby Rash in Skin Folds - Neck, Armpits, and Creases

Rashes in baby's skin folds (neck, armpits, groin, behind ears, elbow and knee creases) are extremely common because these warm, moist areas trap moisture from drool, spit-up, sweat, and milk. The medical term is intertrigo. Most fold rashes respond to keeping the area clean and dry. If the rash is bright red, has satellite spots, or has a yeasty smell, it may have developed a yeast (candida) infection and need antifungal treatment. Keeping folds dry is both the treatment and prevention.

Baby Strong Smelling Urine - Causes and When to Worry

Strong-smelling urine in babies is usually caused by concentrated urine from mild dehydration, certain foods in the diet, or ammonia buildup in a diaper that has been on for a while. Breast milk-fed babies typically have nearly odorless urine, while formula-fed babies may have slightly more noticeable urine odor. If your baby's urine suddenly develops a strong, unusual, or foul smell alongside other symptoms like fever, fussiness, or changes in urination patterns, it could indicate a urinary tract infection (UTI) and should be evaluated.

Milestone

Month-by-Month Development

Detailed monthly development guides from birth through 24 months.

Guide

When to Call the Doctor

General guide on when to call the pediatrician, visit urgent care, or go to the ER.

Frequently asked questions

Is baby or toddler body odor - when is it normal normal?
Babies and toddlers can develop body odor from several benign causes: sour milk caught in skin folds, sweating, diaper area odor, strong-smelling foods in the diet, and certain medications or vitamins. True body odor (like adult BO from apocrine glands) should not occur before puberty. If your baby or young toddler has a persistent unusual body odor that is not explained by skin folds, diaper, or diet, it could indicate a metabolic condition, infection, or foreign body (especially in the nose or vaginal area). Unusual persistent odor warrants a doctor visit.
When should I call the doctor about baby or toddler body odor - when is it normal?
A newborn with a sweet, unusual smell and poor feeding or lethargy - possible metabolic emergency Foul body odor with fever, skin changes, or your child seeming unwell Signs of early puberty (body odor, body hair, breast development) in a child under age 7-8
When is baby or toddler body odor - when is it normal normal?
Sour smell from milk in skin folds or spit-up residue - resolved by cleaning Foot odor from non-breathable shoes or socks Temporary body odor changes after eating strong-smelling foods
What causes baby or toddler body odor - when is it normal?
Babies and toddlers can develop body odor from several benign causes: sour milk caught in skin folds, sweating, diaper area odor, strong-smelling foods in the diet, and certain medications or vitamins. True body odor (like adult BO from apocrine glands) should not occur before puberty. If your baby or young toddler has a persistent unusual body odor that is not explained by skin folds, diaper, or diet, it could indicate a metabolic condition, infection, or foreign body (especially in the nose or vaginal area). Unusual persistent odor warrants a doctor visit. Common explanations include: Sour smell from milk in skin folds or spit-up residue - resolved by cleaning. Foot odor from non-breathable shoes or socks.
What should I mention to my pediatrician about baby or toddler body odor - when is it normal?
You should mention baby or toddler body odor - when is it normal at your next visit if: Persistent unusual body odor that does not resolve with bathing and cleaning. Adult-like armpit body odor in a child under 8. Foul smell from one nostril (likely nasal foreign body).
Is baby or toddler body odor - when is it normal normal at 0-6 months?
Young babies can smell sour from milk pooling in neck folds, behind ears, and in skin creases. Spit-up residue on clothing and skin also creates a sour smell. This is resolved by cleaning skin folds daily and changing clothes when soiled. A sweet or unusual smell from a newborn could indicate a metabolic disorder - maple syrup urine disease, for example, causes a distinctive sweet smell. If your newborn has an unusual smell along with poor feeding or lethargy, seek immediate evaluation.
Is baby or toddler body odor - when is it normal normal at 6-12 months?
As solids are introduced, babies may develop different body odors from their diet. Garlic, onion, and spices in food can cause temporary changes in sweat and urine smell. Strong-smelling feet can develop from shoes or socks that do not breathe. A fishy or foul smell from the diaper area could indicate a urinary tract infection. Clean skin folds regularly and ensure the diaper area is kept dry. If the smell persists after cleaning, it warrants investigation.
Should I go to the ER for baby or toddler body odor - when is it normal?
Seek emergency care if a newborn with a sweet, unusual smell and poor feeding or lethargy - possible metabolic emergency, or if foul body odor with fever, skin changes, or your child seeming unwell. When in doubt, call your pediatrician's after-hours line for guidance.
Does baby or toddler body odor - when is it normal go away on its own?
In many cases, baby or toddler body odor - when is it normal resolves on its own, especially when sour smell from milk in skin folds or spit-up residue - resolved by cleaning. By 2-3 years, true axillary (armpit) body odor before age 8 is unusual and could indicate premature adrenarche (early activation of adrenal glands). If your toddler has genuine adult-like body odor from the armpits, mention it to your pediatrician. They may check for signs of early puberty. Other causes of unusual odor in this age group include: fungal skin infections, certain medications, and rarely, metabolic conditions. Most odor complaints at this age have a simple, benign explanation.
AAPNIHNIH

References

  1. [1]American Academy of Pediatrics. Puberty: Precocious Puberty. HealthyChildren.org. AAP
  2. [2]National Library of Medicine. Body Odor. MedlinePlus. NIH
  3. [3]National Library of Medicine. Metabolic Disorders - Newborn Screening. NIH

Doctor Visit Checklist

Bring this checklist to your next pediatrician visit to discuss Baby or Toddler Body Odor - When Is It Normal?.

Things to mention

  • Describe when you first noticed baby or toddler body odor - when is it normal and how it has changed over time.
  • Note your baby's current age and which age-specific patterns you are seeing.
  • Mention if persistent unusual body odor that does not resolve with bathing and cleaning.
  • Mention if adult-like armpit body odor in a child under 8.
  • Let your doctor know if you have noticed any related concerns, such as changes in feeding, sleep, or movement patterns.
  • Bring a list of any questions or observations you want to discuss at the appointment.

Observations to share

  • Persistent unusual body odor that does not resolve with bathing and cleaning
  • Adult-like armpit body odor in a child under 8
  • Foul smell from one nostril (likely nasal foreign body)

Urgent signs to report immediately

  • A newborn with a sweet, unusual smell and poor feeding or lethargy - possible metabolic emergency
  • Foul body odor with fever, skin changes, or your child seeming unwell
  • Signs of early puberty (body odor, body hair, breast development) in a child under age 7-8

My notes

From ismybabyalright.com — free, evidence-based baby health guides

All content follows our editorial policy and is reviewed against published clinical guidelines.

2,705 evidence-based guides6 authoritative medical sources5 medical advisory board members

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Bottom line

Most cases of baby or toddler body odor - when is it normal are normal. Talk to your pediatrician if a newborn with a sweet, unusual smell and poor feeding or lethargy - possible metabolic emergency.

Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.

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Baby Sweating a Lot - Excessive Sweating

Sweating in babies is common, especially on the head, because babies have a high density of sweat glands on their scalp and their temperature regulation is still developing. Sweating during feeding, sleeping, and crying is usually normal. However, excessive sweating during feeds (especially if the baby also breathes fast or tires easily while eating) can occasionally indicate a heart condition. If your baby sweats heavily with feeds AND has poor weight gain or breathing difficulties, mention it to your pediatrician.

Baby Rash in Skin Folds - Neck, Armpits, and Creases

Rashes in baby's skin folds (neck, armpits, groin, behind ears, elbow and knee creases) are extremely common because these warm, moist areas trap moisture from drool, spit-up, sweat, and milk. The medical term is intertrigo. Most fold rashes respond to keeping the area clean and dry. If the rash is bright red, has satellite spots, or has a yeasty smell, it may have developed a yeast (candida) infection and need antifungal treatment. Keeping folds dry is both the treatment and prevention.

Baby Strong Smelling Urine - Causes and When to Worry

Strong-smelling urine in babies is usually caused by concentrated urine from mild dehydration, certain foods in the diet, or ammonia buildup in a diaper that has been on for a while. Breast milk-fed babies typically have nearly odorless urine, while formula-fed babies may have slightly more noticeable urine odor. If your baby's urine suddenly develops a strong, unusual, or foul smell alongside other symptoms like fever, fussiness, or changes in urination patterns, it could indicate a urinary tract infection (UTI) and should be evaluated.

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