Why Baby’s Gas Smells like Rotten Egg or Sulfur? (What can you do)

Sharing is caring!

Stink alert! Does your baby’s gas smell like rotten egg or sulfur? It may not be normal. Read on to learn what causes a baby’s fart to stink and what you can do about it. 

Everything about the baby is adorable. Even their fart is hilarious and brings a smile to your face with them making faces while farting. 

But it is not adorable anymore when their fart smells like rotten egg or sulfur. 

I was under the impression that breastfed baby’s fart does not smell until my little one turned 2 months old. His fart smelled like a rotten egg but no poop. 

hand holding baby's leg towards tummy _why baby's gas smells like rotten egg or sulfur

And then the baby poop smelled like rotten eggs too! It never annoyed me to change my baby’s diaper before, but the rotten egg smell of his fart and poop made me nauseous. So then I decided to investigate. 

The main reason baby’s farts smell like rotten egg or sulfur is that they may be sensitive to breastmilk or formula. Another possible reason could be something that the mother ate could give a strong smell to breastfed baby’s gas. Digestive issues are also responsible for smelly farts. 

Let’s take a look at why your breastfed or formula-fed baby’s gas smells like rotten egg or sulfur. 

Disclosure: This post may contain affiliate links. As an affiliate and amazon associate, I earn commission on qualified purchases at no extra cost to you. Check our affiliate policy here.

Why does my baby Fart so often?

Farting is normal for a baby. But, unlike toddlers and adults, babies tend to swallow more air, whether breastfeeding or bottle-feeding. 

It is considered normal for a baby to pass gas 20 times a day without having any digestive issues. 

Whether your baby’s gas is stinky or not, several reasons can cause gas build-up in their tummy while bottle-feeding or breastfeeding and cause the baby to fart a lot. 

Immature Digestive System

A newborn has immature digestive systems. Their digestive system still has to mature to digest the proteins, fats, and carbohydrates they consume via breastfeeding or bottle feeding. 

While breast milk is comparatively easy for babies to digest than formula, they still develop gas which causes them to fart. 

Formula-fed baby seems to have more gas issues until their digestive system mature. 

When you see your baby squirming and crying while bottle-feeding or breastfeeding, it is likely that they are having pain from gas build-up in their tummy. 

Feeding position and Techniques

How you feed your baby can also impact how much air they are swallowing while bottle-feeding or breastfeeding. 

If your baby is not latching correctly or latching and unlatching while breastfeeding, they are likely to swallow more air. 

Or, if you feed your baby on their back while bottle feeding, it can cause them to swallow more air compared to when provided in a slanted position. 

There are many variables like type of bottle, nipple, feeding position, and how you are holding your baby that can contribute to the baby swallowing more air while feeding. 

You need to figure out the right position and technique, whether you are bottle-feeding or breastfeeding, to reduce the amount of air your baby is swallowing. 

For a bottle-fed baby, try paced-bottle feeding. It is a method of a bottle-feeding baby that allows the baby to control the amount of milk they are getting from the bottle, thereby reducing the chance of swallowing more air from the bottle. 

Excessive Crying 

It is usual for babies to cry to fulfill their demands. It is their way of communicating with us. But excessive crying can cause a problem. When they cry non-stop for a few hours a day (like a colicky baby), it can cause them to swallow excessive air, leading to excessive farting. 


When a baby is constipated and unable to poop, their gas may stink like rotten eggs. 

When they cannot digest food in their intestinal tract, it causes blockage—constipation in babies. 

Food Sensitivity or Allergy

Food sensitivity or allergy can also cause the baby to fart excessively. 

If you are breastfeeding your baby, what you eat matters. It may be something that you have eaten, causing gas and excessive farting in your baby. 

Cow milk protein allergy is common among newborns. If you see your baby excessively farting along with rashes, congestion, constipation, or diarrhea, it could be a sign that your baby is allergic to cow milk protein.

Some babies have difficulty digesting formula, which can lead to gassiness and excessive farting. In addition, allergy to some ingredients in the formula can be a possibility.

For example, babies allergic to lactose in the formula can have excessive gas, which causes them to fart a lot. In addition, lactose-intolerant babies’ poop smell like vinegar.

If that is the case, talk to your pediatrician about changing the formula to lactose-free formula. 

Why does my baby’s gas smell like rotten eggs or Sulfur?  

The amount of air the baby swallows while feeding, bacteria in the baby’s intestine (digestive health), food that the baby consumes (either breastmilk or formula or solid introduction), allergies, or food sensitivity determines how stinky their fart will be. 

Usually, a baby’s fart does not smell bad, but when it smells like rotten eggs or sulfur, you need to determine its possible causes. 

To determine why your baby’s gas smells like rotten egg or sulfur, you need to determine what is expected and not normal for your baby. For example, was their fart stinky from the day they were born, or has their flatulence been smelly recently? 

Keep an eye on how many times a day they fart, and also determine whether their fart stinks every time they fart or if there is any pattern? 

Once you know, it will be easy for you to find out what is expected and not normal for your baby. 

Depending on their diet, let’s look at why their gas is stinky. 

Why Breastfed baby’s gas smells like rotten egg or sulfur and Solutions

women breastfeeding a baby
Image by sam moody from Pixabay

Breastmilk is easy for a baby to digest, so breastfed baby has fewer digestive issues than a formula-fed baby. But when breastfed baby’ gas smells like rotten egg or sulfur, there may be some issue that you need to find out. 

There are 3 main reasons breastfed baby’s gas smells like rotten egg or sulfur.

Something in your diet

Whatever you eat while breastfeeding, your baby gets that too. If you eat certain foods rich in sulfur, your baby gets them too, which may make their gas smell like rotten eggs or sulfur. Some of the sulfur-rich vegetables include

  • Broccoli
  • Beans
  • Cabbage
  • Brussels sprouts
  • Spinach
  • Kale

However, these foods do not cause concern, as once they are digested in your baby’s stomach, the stinky smell from their gas dissipates too. 

But if your diet contains lots of sulfur-rich meat, then it could be why your baby’s gas smells like rotten eggs or sulfur. 

Sulfur-rich meat includes

  • Seafood – Lobster, scallops, mussels, oysters, salmon, sardines, cod, crab
  • Organ meat – Heart, liver, and kidneys
  • Other meat – Beef, Veal, chicken, and pork

Also, eating eggs can cause a baby’s gas to smell like rotten eggs. 

If you want to find out why your baby’s strong fart smell, eliminate the sulfur-rich food from your diet and see if it makes any difference in smell. After a few days, start eating sulfur-rich food again and see if the smell returns. 

Keep in mind that it takes more than a couple of days for foods to clear from your body and then another week to clear from your baby’s body. So, be patient to see a result. 


Infection in a baby’s stomach can also cause their gas to smell like rotten egg or sulfur. 

Infant gastroenteritis is an infection of the stomach and intestines, common among babies and children.

It is caused by bacteria or viruses in the gastrointestinal tract. Non-hygienic practice while handling a baby can cause bacteria or viruses to enter the intestinal tract.

So, when it is very important to wash hands and clean your breast regularly while showering to prevent infant gastroenteritis. 

Infant gastroenteritis symptoms include diarrhea and vomiting and can lead to dehydration. So, if you see any of these symptoms, talk to your pediatrician. 

Related read: Best uses of Expired Formula

Cow’s Milk Protein Allergy

Cow’s milk protein allergy is the most common childhood allergy. It happens when a baby’s immune system reacts to one of the cow’s milk proteins.

It causes digestive issues like abdominal discomfort, pain, and excessive crying and can cause the baby’s gas to smell like rotten eggs. 

If you are consuming dairy products like milk, cheese, yogurt, ice cream, or any food with milk or milk products, casein, or whey when breastfeeding, it may give your baby trouble if they are sensitive to cow’s milk protein. 

But this does not mean you have to severely limit your diet on the hunch that your baby might have a milk protein allergy. 

But if you suspect that dairy is a culprit for your baby’s gas to smell like rotten eggs or sulfur, try eliminating dairy for a week and see what happens.

If your baby’s gas does not smell that strong in a few days, you know that dairy is the problem. 

Why Formula-fed baby’s gas Smells like Rotten egg or Sulfur and Solutions 

women bottle feeding a baby
Photo by Nathan Dumlao on Unsplash

The formula is harder for the baby to digest than breast milk. When a baby is formula-fed, many factors cause the baby to swallow air while feeding, causing excessing farting. 

But when their fart smells like rotten eggs or sulfur, there may be sensitivity to formula ingredients involved. 

If you are feeding your baby cow-milk-based formula, ingredients like lactose, casein, and whey formula can make it harder for the baby’s underdeveloped digestive tract to digest. This may result in their gas smelling like rotten eggs or sulfur. 

Other ingredients in the baby formula that might also be harder for the baby to digest include wheat protein, grain protein, sugars, and flavors. 

If you think your formula-fed newborn’s fart smells like rotten eggs, talk to your pediatrician about changing their formula. Some doctors recommend changing the formula to see gassiness and smell reduced. 

With formula-fed babies, consider changing their feeding position or feeding techniques, bottle, or nipple before you change their formula. Sometimes, swallowing too much air while feeding causes excessive gassiness and farting.

If nothing seems to work and their gas still smells like rotten egg or sulfur, try changing their cow-milk-based formula to lactose-free formula to see if it reduces the smell. 

The baby or Toddler has Smelly Gas but no Poop

The newborn should have a bowel movement once a day for the first month of their life. But for breastfed babies- as they grow older (6 weeks), they can go without pooping for a week or two because their body can digest all the components of breast milk without the need to eliminate any of it. 

But that is not true for bottle-fed babies. When bottle-fed babies go without pooing for 3-4 days, they are constipated.

They may be passing frequent gas, but no poop is a common sign of constipation. 

Constipation in babies indicates that they have a poop build-up in their intestines. When they can not pass the poop, it causes bacteria and a foul smell build up. This result in painful and foul-smelling gas. 

Talk to your pediatrician if your baby or toddler has smelly gas but no poop. 

How to Help Baby to Relieve Gas

The main culprit for digestive issues in babies is air swallowing while feeding. If you can help your baby limit their air consumption while feeding, gassiness will decrease significantly and ultimately fart. 

Here are a few common things you can do to limit air swallowing while feeding.

Feeding positions for gassy baby

Keep baby in a little upright position while feeding. Holding the baby in an upright or semi-upright position allows the baby to control the flow of the milk, thereby reducing the amount of air they are consuming.

Also, when babies’ heads are higher than their bellies, milk will go bottom of their stomachs, and air bubble comes to the top. So, when you burp your baby, that air will easily come out. 

You can also hold the baby in an upright or semi-upright position and try paced bottle feeding method. In this bottle-feeding method, babies can control the amount of milk they are taking, thereby reducing the amount of air they are taking in. 

Oversupply of breastmilk or overactive letdown

If you have an oversupply of breastmilk or have an overactive letdown while breastfeeding, it can cause the baby to swallow more air. In case of an oversupply of breastmilk, you may want to pump your breastmilk to make it manageable for your baby.

With an overactive letdown, you may want to unlatch your baby and collect the letdown in a towel and when the letdown subsides, put your baby back to the breast. 

In both of these cases, you can try laid-back breastfeeding, where gravity helps you reduce the flow of the milk.

The side-lying position also works effectively when you have an oversupply of breast milk, as the baby will be able to dribble extra milk out of their mouth

Burp, Burp, and Burp

Burping frequently while feeding helps release trapped air bubbles from the baby’s stomach. For a baby with excessive gas, burp your baby every few mls of milk or burp them halfway through a bottle and at the end of the bottle. 

Belly massage

Giving your baby a massage regularly can also help relieve trapped gas from the baby’s stomach.

Move your fingers through your belly’s baby like you are writing ‘I LOVE YOU’ in their tummy, as shown in this video, which helps the baby relieve gas from their tummy.

Also, gentle bicycle exercise on the baby’s leg when they are lying also helps relieve excessive gas.  

Check the bottle nipple.

If you are using a fast-flow nipple, then it can cause your baby to swallow air. So, try a slow flow nipple, and when the baby is a little older and able to handle the flow of the milk, you can switch to a fast flow nipple. 

Check out this detailed article on how to relieve gas pain in babies


When a baby’s gas smells like rotten egg or sulfur, the main culprits are what they have been eating. Whether breastfed or formula-fed, there is something in their food that they can not digest and causes their gas to stink like rotten egg or sulfur.

So, keep a diary of what you or your baby have been eating to find out what causes the baby’s gas to stink like rotten eggs or sulfur. 

Similar Posts