Breastfed Baby Gas Smells Like Rotten Eggs: 4 Common Causes

| Reviewed By Sarah Schulze, MSN, APRN, CPNP

Having a baby opens up a whole new world of experiences for parents, including new aromas. The scents of formula, baby shampoo, and newborn feces are all unique and identifiable.

But sometimes you’ll catch a whiff of something out of the ordinary, like rotten eggs. 

Why does my breastfed baby’s gas smell like rotten eggs? A breastfed baby’s gas can smell like rotten eggs due to infections, allergies, or the mother’s diet. All of these underlying causes can be aided or treated with small lifestyle adjustments. Before determining how to resolve the issue, consult with your child’s pediatrician and your doctor. 

Keep reading to learn more about why your baby’s gas may smell like rotten eggs and how to get rid of it. 

Breastfed Baby Gas Smelling Like Rotten Eggs: 4 Causes

There are several reasons why a baby’s gas may smell like rotten eggs. Luckily, most of them are avoidable with planning and preparation. We’ve compiled a list of the most common culprits behind the smell below.

1. Mother’s Diet Is High in Sulfur

A breastfeeding mother’s diet has a significant impact on the quality and content of her breast milk.

When a mother’s diet is high in sulfur-rich foods like vegetables, eggs, meats, and dairy, those sulfur compounds will make their way into the breast milk.

Since a baby’s primary source of nutrition for the first year of life is breast milk, the smell of the baby’s urine, gas, and poop is influenced directly by it. 


If you’re looking to rid your baby’s gas of a strong sulfur smell, try reducing your overall sulfur intake. However, sulfur is abundant in most foods, making it difficult to avoid. 

Beyond that, sulfur plays a vital role in reducing the risk of chronic ailments like cardiovascular and neurodegenerative diseases. So, it’s important for the health and function of our bodies. 

If the smell doesn’t bother you, there is no harm in maintaining a well-balanced diet with a moderate sulfur content. 

2. Lactose Intolerance

Children under the age of one are not supposed to have cow’s milk. Their immature digestive systems cannot handle the amount of protein it contains compared to human milk.

Cow’s milk protein is one of the few compounds that crosses directly over into breast milk, and most traditional infant formulas are also made using cow’s milk protein.

Some infants are more sensitive to exposure to cow’s milk protein and develop an intolerance. This is not the same as an allergy and may be outgrown as the child grows and their digestive tract develops.

Infants with a cow’s milk protein intolerance may experience excessive gassiness, fussiness, or even stools with blood or mucous in them. 


Breastfeeding mothers of infants with cow’s milk protein intolerance can eliminate dairy products from their diet, and babies who receive formula can be switched to an amino acid or soy-based formula.

Reducing the overall consumption of cow’s milk protein will help relieve the smelly gas and other associated symptoms. 

3. Gastroenteritis

Gastroenteritis is the technical term for a common ailment known as the stomach flu. A usual symptom of the stomach flu in infants is diarrhea, and with that comes pungent gas.

While this usually relieves itself within a matter of days, there are ways you can lessen the effects of the infection. 


The largest concern with the stomach flu in infants is dehydration. Keep your child hydrated by any age-appropriate means such as formula, Pedialyte, water, or breast milk.

Doing so will alleviate many of your child’s symptoms, including their stinkiness.

Rotavirus is one of the most dangerous causes of gastroenteritis and serious dehydration and can be avoided through the administration of regularly scheduled vaccines. 

4. Food Allergy

Common food allergies such as soy, dairy, wheat, eggs, and nuts can still develop in exclusively breastfed babies. Trace amounts of these foods can be found in the mother’s breast milk and passed to the breastfeeding child.

If the child has an allergy, their body views those foods as a threat and attacks them. This causes many symptoms, including diarrhea and colic, both of which lead to smellier gas. 


If your child has an allergy, they will show symptoms such as fussiness, diarrhea, constipation, vomiting, or skin rashes following your consumption of particular foods.

To aid in your child’s digestion and reduce symptoms, you’ll need to remove those foods from your diet. However, you should consult your doctor before completely cutting out any food or food group to ensure optimal health. 

Breastfed Baby Poop Smells Like Rotten Eggs

Breastfed baby poop may smell like rotten eggs for many reasons. It could be the result of high-sulfur consumption, the presence of lactose, or other common food allergens in the mother’s diet.

The best remedy for this issue is to remove or reduce the intake of said foods. This should be done under the supervision of a doctor or pediatrician.

Another reason breastfed baby poop may smell is due to infections or illnesses in which diarrhea is a symptom. Diarrhea is often far more pungent than regular bowel movements. These smelly poops can tell parents a lot about their child’s health. 

Parents holding their smelly baby girl in need of a diaper change.

Is It Normal for Breastfed Babies To Have Smelly Gas?

Yes! It’s normal for breastfed babies to have smelly gas. The type of smell that a baby toot emits can be indicative of food sensitivities, a result of their immature digestive systems, or a measure of how well they’re tolerating their mom’s diet.

Then again, a baby fart may have no smell at all. In any case, if you have concerns about the smelliness of your child’s gas, it is always beneficial to ask their pediatrician. 

Positions To Relieve Gas in Babies

If your little one is struggling to pass gas on their own, there are things you can do to assist. There are different positions that can be beneficial to relieve gas in babies.

  • Tummy Time: It’s more than just a fun time for your baby. Pressure on the abdomen can aid in digestion by breaking up air bubbles. In addition, your child’s wiggling and stretching can encourage the movement of gas through the body. 
  • Cycling: Laying on the back is one of the best positions for gassy babies. To complement this position, the cycling of the legs to and from the chest encourages the gas to travel through the intestines at an efficient rate. 
  • Knees to Chest: Similar to the tummy-time method, pressure from the legs onto the abdomen can aid in digestion by breaking up air bubbles. In addition, the pressure encourages the passing of gas through the intestines. Meanwhile, the curvature of the rectum allows gas to escape more efficiently. 
  • Baby Wearing: Not only does baby-wearing keep your little one close and secure, but it also puts them in an upright position with mild pressure on their abdomen, all of which facilitates gas working its way through. 

Breastfed Baby Smelly Gas, No Poop

It’s common for a baby to pass gas without pooping. When a baby feeds, they may take in a lot of additional air. That air has to find a means of escape either through burping or passing gas.

While gas can mean that a bowel movement is on the way, it can also be the result of a particularly rushed feeding. An overly gassy baby may be taking in excessive amounts of air during feedings.

Have your baby’s latch checked for issues that may cause excess air intake, or for bottle-fed infants, be sure you are using vented bottles and a nipple flow speed appropriate for their age

When To Be Concerned About Your Baby’s Gas

If your baby’s gas is accompanied by any of the following symptoms, you should consult their pediatrician immediately: 

  • Periods of inconsolable crying lasting 3 hours or more multiple days a week.
  • Poor weight gain or significant weight loss.
  • Frequent vomiting. 
  • Fever of 100.4 or higher.
  • Blood in the diaper.
  • Bloated or hard stomach that does not retreat after passing gas or burping.

Related Questions: 

Why Is My Baby Not Burping?

It may be concerning to parents when their baby doesn’t burp after a feeding, but rest assured, this isn’t necessarily a bad thing.

Some babies simply don’t take in too much air while eating. Other times a baby may be too sleepy or in an ineffective position to let the burp out. 

Either way, as long as your baby seems content after a feeding session, they should be okay.

Look for signs of distress and discomfort such as a hard belly, fussiness, or pulling their legs to their belly. These can be indicative of trapped gas. 

What Color Should Newborn Poop Be?

The first few soiled diapers that a newborn has should contain a substance called meconium. This will be a black, sticky, tar-like substance.

After the first few days, you should start to see mustard-yellow, green, or brown poop that’s gritty in texture.

Wrapping It Up

Breastfed baby gas can smell like rotten eggs for many reasons. The sulfur-like smell occurs when the mother’s diet is high in sulfur or when a food allergy is present.

It can also happen as a result of the baby’s immature digestive system or can be indicative of issues within the digestive tract.

If you’re concerned about the reasoning behind your baby’s smelly gas, it’s best to consult your child’s pediatrician.