Formula Fed Baby’s Gas Smell Like Rotten Eggs

By admin

Passing gas is normal for all babies and part of the digestion process. But while this is perfectly natural, there are times when it may become more of a concern. 

Smelly gas that has a sulfur or rotten egg smell is not only unpleasant, it can result in mothers wondering if their baby is experiencing any digestive issues that may require treatment.

Below, we shall discuss why this happens and if it should be a cause for concern.

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Formula-fed Intolerances

For babies not breastfed, smelly farts aren’t necessarily a cause for worry. Usually, if you find your baby’s wind begins to smell like rotten eggs, it could simply be that he or she is having difficulties digesting the formula.

This can happen for a number of reasons. Sensitivity to the formula or even an intolerance to the lactose can result in smellier wind.

Although it is uncommon for babies to have an intolerance or even an allergy to lactose.

Sensitivity to ingredients within the formula is far more likely a cause. Besides smelly gas, there are other signs to look out for that may indicate intolerance to one of the ingredients. 

Firstly, as babies develop, so do their digestive systems. It is perfectly normal for your baby to experience gas, spitting up, crying or general fussiness after feeding and aren’t anything to worry about in general. 

These issues typically resolve themselves after a few months. However, many parents may feel that changing their baby’s formula will prevent these issues.

Unfortunately, this can actually exacerbate the problem. 

Before changing their formula, first it is important to look out for other signs that can indicate an intolerance. There are several, and these include:

  • Blood/mucus in your baby’s stools
  • Diarrhea
  • Vomiting
  • Continuous crying 
  • Pulling legs up toward the belly, displaying signs of pain

If your baby shows any of these symptoms, always speak to your healthcare provider, especially where diarrhea is concerned, as this can lead to dehydration.

Some symptoms such as continuous crying and pulling their legs up, can also indicate colic. We will discuss this next.


No one knows for certain why some babies get colic. Breastfed babies can also develop it as much as formula-fed ones.

Some doctors believe that colic is caused by a cow’s milk allergy which in turn, causes cramps within the baby’s digestive system resulting in continuous crying and often pulling their legs up to their tummy in an effort to relieve the discomfort.

There are ways to reduce symptoms of colic if you feel this is what your baby has. 


Always make sure after every feed, you burp your baby to ensure there is no trapped wind. Trapped wind can be painful enough for an adult, and it is no different for a baby.

The only difference is they can’t describe their symptoms or tell you where it hurts.

You can also burp them in-between feeding to remove excess wind, allowing them to continue feeding without discomfort.

Make sure there are no air pockets in the bottle. This can also cause a build of wind in your baby if they are swallowing the air with the formula. 

Upright Feeding

Sitting your baby upright can help in reducing the possibility of colic when feeding them. Keeping them as straight as possible can limit the amount of air they may swallow while feeding. 

Also, try to keep them upright after feeding for around 30 minutes to help any remaining air find its way out. 

Different Teats

You can also try different teats. Some mothers may opt for a fast-flow teat, while others find a slow-flow one better.

Trial and error can determine what is best for your baby. 

As a rule of thumb, slow-flow teats with smaller holes are designed for newborns, while medium is for babies who are three-plus months old and fast-flow is for those aged six-plus months.

By six months, however, many babies begin weaning and therefore, the food they eat can cause their wind to take on a range of unusual smells. 

There are also bottles that are specifically designed for babies prone to colic. These have small air vents, tubes or collapsible bags designed to reduce the amount of air your baby may swallow during a bottle feed.

Tummy Massages

Another thing to try for babies who may have trouble passing wind is to give them gentle tummy massages. Rub your hand in a clockwise direction on their bellies to help any stubborn gas pass through their gut.


Another sign of baby gas that smells like sulfur is a possible stomach infection. This will be accompanied by other symptoms too, such as a change in their stools or amount of gas, vomiting, fussiness, and fever. 

If your baby’s temperature is above 100.4 degrees Fahrenheit and they are under three months old, you must always seek guidance from your doctor, who can check your baby’s health and provide advice.

If your baby shows signs of dehydration due to vomiting or diarrhea, suggests giving your infant electrolyte solution rather than water to replace the salts lost during sickness.

These can be bought from most drug stores and always read the instructions on how much to administer.

Cow’s Milk Allergy

Although we have mentioned an allergy is rare in babies, these can occur. There are various symptoms to look out for that indicate an allergy over an intolerance.

A cow’s milk allergy, or CMA, is where a baby develops a reaction to the protein in the milk. 

According to, it’s estimated to affect around 7% of babies under the age of one and most children grow out of it by the age of five. 

There are two main types of CMA:

  • Immediate CMA. This is when symptoms appear within minutes of consuming cow’s milk.
  • Delayed CMA. This is when symptoms do not present themselves for several hours or even days after taking cow’ milk.

The symptoms of such an allergy usually present themselves as:

  • Eczema that does not improve with topical treatments
  • Red itchy rashes or swelling of the lips, face and eyes
  • Digestive problems such as constipation, diarrhea, cramps, colic
  • Runny or blocked nose (when there is no evidence of a cold)

If you do think your baby may have an allergy to the formula, first speak to your doctor, as they can suggest alternatives such as lactose-free formulas.

This will also apply to babies who experience intolerances to cow’s milk.

If your baby shows no signs of improvement after changing to lactose-free versions, always speak to your doctor first rather than continuously change formulas.

As already discussed, it takes time for your baby to adjust and constant changing of their feed can worsen symptoms.


Certain medications prescribed by your doctor for your baby may cause excessive wind.

Always check the side effects on the information leaflet to make sure you know if their reaction is normal and whether to seek medical help, if it becomes persistent.

Your doctor may be able to change the medication to something that won’t aggravate your baby’s stomach or he or she may advise you to reduce the dosage. 

Final Thoughts

As we have shown, if your baby experiences smelly gas that has a rotten egg smell to it, there often is no cause for concern and is perfectly normal.

Every baby is different, and while some produce little odor, some will naturally produce more.

However, as always, trust your instinct. If you feel something is not right, always speak to your doctor or healthcare provider first. They can check your baby for signs of allergies and provide advice on how to manage the symptoms.