Bad Breath in Children – Innocent Symptom or Alarm Signal? Get the Expert's Opinion!

Why does a child's breath stink, despite daily, thorough brushing of teeth? When parents search the Internet for information about unpleasant breath from their child, they come across many answers - from reflux and metabolic diseases to the suspicion that the culprit may be... parasites. And what if your little one's breath smells of acetone - is this a cause for concern? Are you wondering how to distinguish between Internet "panic" and real signals that something may be wrong with your child's health?

In this article, IMiD expert, dentist, Dr. Alicja Zawiślak, M.D. explains the most common causes a strange smell from the child's mouth and advises parents what to do when we observe baby bad breath.

Halitosis in children – or strange smell from the mouth always indicates a serious problem?

Before we start looking for the cause of a strange odor from a child's breath, it is worth answering a basic question: what exactly is bad breath? Chronic, unpleasant odor from the mouth, known as halitosis, is an ailment which, as statistical data show, can affect even 25 to 50% population, including children.

When you notice an unpleasant odor from your child's mouth, don't assume the worst — in many cases, bad breath is a temporary problem, related to, for example, the time of day, occasional changes in diet, or a temporary decrease in hygiene.

However, if the strange odor from your child's breath persists for several days or longer, despite diligent care for oral hygiene, do not delay consultation with a doctor. pediatrician and/ or dentist.

Why does a child's breath stink? after waking up, is it normal? 

Physiological halitosis, or the so-called morning bad breath in a child, is a phenomenon that occurs quite commonly in the population - why does a child's breath stink right after waking up?

Parents are more concerned about a strange, persistent and distinct odor from their child's mouth that does not go away despite regular teeth brushing and oral hygiene - what could be the cause of pathological halitosis?

Unpleasant odor from the child's mouth, as a symptom of health problems – what is worth knowing and when to see a doctor?

Pathological halitosis is most often associated with poor oral hygiene or mild health problems, but it can also happen bad breath - for example the smell of acetone from the child's mouth – may signal more serious ailments within the toddler's body. Pathological halitosis is divided into two main types: that which originates in the oral cavity, and that which is related to health problems in other parts of the body.

Why does a child's breath stink?? The cause may be in your mouth!

The most common causes of pathological halitosis in children are related to the oral cavity (they account for up to 80-90% of cases):

• Poor oral hygiene: This is the most common solution to the puzzle titled: "Why does my baby's breath stink?". It happens that despite regular brushing, teeth are not cleaned thoroughly, which is why it is so important to brush them at least twice a day - in the morning and especially in the evening, just before going to bed, not forgetting the interdental spaces (flossing). It is worth remembering that even up to approx. 10th year of lifeand the child still needs parent support and control during daily oral hygiene. 

• Deposits on the tongue: A characteristic layer of deposits may appear on the back of the tongue, which is caused by the accumulation of dead epithelial cells, food residues and microorganisms. This so-called tongue coating is not always noticeable, but it can be a source unpleasant odor from the child's mouth.  
• Tooth and gum diseases: Dental caries, abscesses, gingivitis and periodontitis are disease states that are often accompanied by a strange smell from the child's mouth.
• Reduced saliva production (sialopenia/hyposialia): Various factors, such as: certain medications taken by the child, dehydration or mouth breathing (blocked nose + unpleasant odor from the mouth), can lead to dry mouth (xerostomia, which is a result of sialopenia).

Drying of the mucous membrane promotes the growth of bacteria and the development of an unpleasant odor - the already mentioned bad morning breath is an example of physiological xerostomia.

• Oral infections (e.g. thrush, erosions): strange smell from the child's mouth, may be caused by bacterial, viral or fungal infections of the oral cavity.
• Improperly made fillings or prosthetic restorations: They can be a retention site for bacteria and food residues, contributing to unpleasant odor from the child's mouth.
• Teething: local, temporary inflammation of the gums may accompany the eruption of primary teeth, but also permanent teeth, becoming the cause bad breath in a child.

Blocked nose and bad breath in a child, or maybe weird the smell of acetone: Check what else can cause halitosis 

Less common causes of pathological halitosis in children, not directly related to the oral cavity (accounting for about 10% of cases), include:

• Upper respiratory tract infections: in the course of a cold, sore throat or sinusitis, the child may have Stuffed nose, and at the same time it appears to him unpleasant odor from the mouth. 

• Constant mouth breathing, or the so-called "always open mouth" in a child: may have various causes – from enlarged or inflamed tonsils, through chronic rhinitis (already mentioned, Stuffed nose), up to anatomical defects and/or muscle tone disorders.
• Foreign body in the nasal cavity: Young children sometimes put objects up their noses - if the object is not removed and an infection occurs, it can cause a strange smell from the child's mouth.
• Gastroesophageal reflux disease (GERD) and other gastrointestinal diseases: Although gastrointestinal diseases are rarely the direct cause of halitosis in children, in some cases, especially with severe reflux, stomach odor may penetrate into the mouth.
• Metabolic diseases: Some metabolic diseases such as diabetes (where it can occur) the smell of acetone from the child's mouth), liver or kidney failure, may cause characteristic bad breath in a child, related to the presence of specific metabolites in the exhaled air.

In the case of fish breath disease (trimethylaminuria) this smell resembles fish: Fish odor syndrome is a metabolic disorder in which the body is unable to properly break down trimethylamine (TMA). 

• Diet: After eating garlic, onions or spicy spices, a short-term, bad breath from a child's mouth. In a child's daily diet, it is worth avoiding snacks that easily stick to the surface of the teeth - such as crisps, jelly candies or chewy candies - because they promote the growth of bacteria in the oral cavity.

Bad breath in children and parasites — fact or myth?

Although the topic of parasites often comes up in conversations with parents, in light of current scientific research, unpleasant odor from the mouth in children it is rarely directly related to a parasitic infection. However, if the child has unpleasant breath and other disturbing symptoms, such as: abdominal pain, appetite disorders, problems with defecation or chronic fatigue, it is advisable to consult a doctor who will examine the child, assess the general state of health and, if necessary (eg if parasitic infection is suspected), will order additional diagnostics.

Although parasites are not a typical cause of halitosis, they can affect the overall condition of the body, which is why it is always worth approaching the matter comprehensively, consulting any concerns with a doctor.

What to do if you notice a strange odor coming from your child's breath?

You already know why your child's breath smells and what the potential causes of halitosis may be, so if despite proper oral hygiene, persistent bad breath appears - the smell of acetone, rot, fermented fruit - do not delay the consultation with pediatrician and/ or dentist. Based on the interview and examination conducted in the office, the doctor will be able to assess the most probable cause of halitosis and, if necessary, will recommend additional diagnostics and/or consultation with another specialist, e.g. a gastroenterologist or endocrinologist.

Quick diagnosis of the cause unpleasant odor from the child's mouth and taking the right actions is of great importance for his health and everyday well-being.

Bibliography (all accesses to internet sources as of April 09.04.2025, XNUMX): 

1. Magdalena Nowak, Wiesław Hędzelek, Halitosis — etiology, diagnosis and treatment — literature review, DENTAL FORUM /2/2018/XLVI, pp. 213-219: https://dentalforum.ump.edu.pl/uploads/2018/2/213_2_46_2018.pdf
2. Łukasz Sroczyk, Beata Kawala, Halitosis – a review of the literature, Dent. Med. Probl. 2011, 48, 2, 255–260: https://www.dbc.wroc.pl/Content/9827/PDF/x15-sroczyk.pdf
3. Natalia Szeląg, Halitosis, DENTAL ASSISTANCE, 4/2016 pp. 22-25: https://smigiel.net/wp-content/uploads/2017/03/halitoza.pdf
4. Anna Pieniążek, Mariusz Pietrzak, Halitosis – etiology, diagnostic methods and treatment, Journal of Health Study and Medicine 2/2017, pp. 101-122: https://jhsm.san.edu.pl/wp-content/uploads/2020/01/JHSM_6_6.pdf
5. Maria Chomyszyn-Gajewska, Agata Skrzypek, Halitosis – diagnosis and treatment, Przegląd Lekarski 2013 /70/2, pp. 65-68: https://ruj.uj.edu.pl/server/api/core/bitstreams/45dabed9-8dca-4da6-8804-988b9cb60cb4/content 
6. Agata Dudzik, Agnieszka Cabała, Maria Chomyszyn-Gajewska, Halitosis – a short history of fighting the problem, Przegląd Lekarski 2018 /75/02, https://ruj.uj.edu.pl/server/api/core/bitstreams/358348ea-8fb8-4c00-b575-33d0e98d8cdf/content
7. Dmitry Tretyakov, Andrzej Skorek, Halitosis as an interdisciplinary problem, Pol Otorhino Rev 2019: 8 (4): 9-14: https://psjd.icm.edu.pl/psjd/element/bwmeta1.element.ceon.element-cf5126f2-1efb-3702-9464-df184c921789/c/pdf-01.3001.0013.5601.pdf