Everybody loves the smell of a new baby.
There’s probably not a person on the planet who doesn’t love that fresh newborn scent.
Mothers become mesmerised by the smell as they snuggle their noses in their newborns’ faces.
Science tells us the beautiful new baby smell causes a surge of dopamine – a feel-good hormone – in new mothers.
There’s even a pretty, white flower called ‘baby’s breath’ whose name was inspired by the delicate aroma.
But what happens if your baby doesn’t smell so sweet?
What if your baby’s breath smells like rotten eggs?
Common causes for bad breath
Although bad breath in babies is relatively common, it can’t be described as normal. If your baby’s breath smells like rotten eggs, it’s important to find out why.
Some common causes of bad breath are:
- Gastroesophageal reflux
- Poor oral health and hygiene
- Dummy/pacifier use
- Thumb sucking.
Let’s take a closer look at these common causes to help find the culprit and get your baby’s breath smelling sweet again!
Gastroesophageal reflux (reflux)
Gastroesophageal reflux, or reflux, is common in infants. This is due to the anatomy of their immature digestive system.
In adults, there’s a sphincter (a ring-like muscle) at the top of the stomach. This muscle tightens after eating, and prevents food from travelling back up the esophagus (the food pipe).
In infants, the sphincter doesn’t tighten in the same way it does in an adult. As a result, food can travel back up into the esophagus more easily. This is what we call reflux.
This is also made worse because, in babies under 6 months, the diet is 100% liquid.
Babies also spend a lot of time lying on their backs, so food easily passes back up the food pipe before it is properly digested in the stomach.
In relation to reflux, if your baby’s breath smells like rotten eggs it is due to the way food is digested.
When food is broken down in the mouth and digestive system, a compound called hydrogen sulfide is produced. This is a normal part of digestion.
Sometimes, however, it is produced in excessive amounts. This leads to bad smelling breath.
You can read more about this in BellyBelly’s article Reflux in Babies – 10 Common Questions Answered.
It’s unlikely for reflux to be the cause of foul-smelling breath if your baby is exclusively breastfed.
Continue reading to find out what else could be to blame.
Another possible cause of bad breath in a baby can be bacteria.
This can be from a bacterial infection, or from an overgrowth of bacteria in the mouth from other causes.
In the case of a bacterial infection, like tonsilitis, the best course of action is to seek medical attention. Your doctor might prescribe a course of antibiotics to kill the bacteria that are causing your baby’s bad breath.
Other bacteria can form in the mouth from too much sugar in the diet.
If your baby has started on solids, he could be consuming too many sugary foods and drinks. This can contribute to an overgrowth of bacteria in the mouth.
Giving your baby a bottle of formula or other milk at bedtime can also contribute to bacteria in the mouth.
This happens if babies fall asleep while the bottle is still dripping into their mouths.
When babies sleep, there’s less saliva in their mouths. Milk dripping from the bottle coats their teeth and gums and sits there for a long time, increasing the risk of bacterial growth.
It’s ok to give your baby milk at nighttime, but you need to make sure his gums or teeth are properly wiped or cleaned before going to sleep.
This doesn’t apply to breastfed babies as breast milk helps prevent dental cavities.
Poor oral health and hygiene
Poor oral health and hygiene can lead to foul-smelling breath.
Good oral health and hygiene start in infancy. This follows on from earlier advice to limit sugary foods and drinks and not to let your baby fall asleep with a bottle.
You can also ensure good oral hygiene for your baby by doing the following:
- Gently wipe your baby’s gums with a face washer twice a day
- As soon as your baby’s first tooth appears, start cleaning with a soft toothbrush and water twice daily; don’t use toothpaste in children under 18 months
- If your baby uses a dummy, never dip it in anything to sweeten it (i.e. honey, sugar)
- Make sure your child has had a formal oral assessment (by a dentist or maternal health nurse) by the age of 2 years.
Following these steps will help minimise bad breath due to bad oral hygiene habits.
Allergies can often lead to sinusitis. This is when the nasal passages become inflamed and cause a stuffy nose.
When your baby’s nose is blocked, he’ll start to breathe through the mouth. Mouth breathing causes a very dry mouth, which means your baby’s breath smells like rotten eggs.
Allergies can also cause extra mucous in the sinuses.
When your baby has a stuffy nose and lies on his back, the mucous falls down to the back of the throat; this is called post-nasal drip.
The mucous can increase the number of unhealthy bacteria in the mouth, which can also cause bad breath.
Allergies or intolerances to certain foods can also be the culprits for causing bad breath.
Lactose intolerance is the inability to digest the sugars in milk and other dairy products.
When people who are lactose intolerant consume dairy, hydrogen sulfide is produced in excess amounts.
This is the same compound responsible for smelly breath related to reflux, and both give off the distinctive odour of rotten eggs.
If your baby is exclusively breastfed, it might be something you’re eating that is affecting your baby. Before eliminating anything from your diet, seek professional advice from a registered dietician.
Bacteria from your baby’s mouth is transferred to his dummy (pacifier) and vice versa.
It is important to sterilise your baby’s dummy regularly, to reduce the chance of any harmful bacteria entering your baby’s mouth.
You can do this by placing the dummy in boiling water for 5 minutes. Make sure all parts of the dummy have completely cooled down before you give it back to your baby.
Dummies can cause lots of problems in relation to oral hygiene and development; for that reason, they aren’t recommended for long-term use.
A dummy is a huge emotional comfort for many babies. This is completely understandable, as sucking helps your baby to relax.
If your baby’s breath smells like rotten eggs and you think it’s related to dummy use, and if your baby is more than 1 year old, it’s time to think about ditching the dummy.
If your baby is having trouble giving up the dummy, you can read some helpful tips in BellyBelly’s article Ditching the Dummy – Tips and Ideas for Stopping.
Thumb sucking is an extremely common habit in babies and children. Some studies suggest that up to 80% of children will go through a period of thumb sucking before they are 4 years of age.
Although it’s generally not considered to be a problem in children under the age of 4, thumb sucking can be a contributor to bad breath.
Sucking or chewing continuously on any object can lead to dry mouth. As mentioned earlier, dry mouth can lead to an excess of bacteria in the mouth, which is a culprit for bad breath.
As experts agree, most of the time no intervention is needed in your child’s thumb sucking. Most children will completely stop sucking their thumbs by 2-5 years of age.
If you’re concerned about how often your child is sucking his thumb, or you’ve ruled out other causes for bad breath and think thumb sucking is to blame, speak to your child’s pediatrician about tactics to help him stop the habit.
Less common reason a baby’s breath smells like rotten eggs
Most of the time, when a baby’s breath smells like rotten eggs it is due to a common cause that can be treated easily.
Sometimes, though, it can be the result of a less common or even serious matter.
A foreign object
Sometimes babies can accidentally get a foreign object (like a piece of food or a tiny toy) stuck in the nose.
This nasal blockage can cause a baby’s breath to smell bad.
If you think your baby might have something stuck up his nose, seek medical help to remove the object.
The bad breath caused by diabetes is often described as sweet or fruity, rather than smelling of rotten eggs. The reason for the odour is the presence of ketones, which are released into the body due to inadequate insulin production.
Other possible symptoms of diabetes are:
- Extreme thirst
- Frequent urination
- Sudden weight loss.
Diabetes can cause long-term effects on many systems of the body.
If you have any suspicion that your child has diabetes, it’s very important to seek immediate medical assistance.
Chronic kidney disease
As well as having bad breath, children with chronic kidney disease often display the following symptoms:
- Chronic urinary tract infections
- Poor appetite
- Stunted growth.
Chronic kidney disease results in life-long damage to the kidneys or a permanent reduction in kidney function.
If you have any suspicion your child has chronic kidney disease, it’s very important to seek immediate medical assistance.
Throughout this article, we’ve discussed lots of different possible causes for bad breath in a baby.
If your baby’s breath smells like rotten eggs, or even if it’s a less offensive odour, the best course of action is to talk to your baby’s doctor.
It might be something as simple as your baby having a blocked nose, but it’s best to rule out anything serious.
All bad breath has a cause. Once the cause can be found, the problem can be fixed and you can go back to enjoying your beautiful, sweet-smelling baby.