6 common causes of mouth ulcers in kids

mouth ulcers

6 common causes of mouth ulcers in kids

mouth ulcers

Mouth ulcers, also known as canker sores or officially known as Aphthous stomatitis, can range from being minimally irritating for your child to downright painful.

A small one here and there that heals quickly on their own may go unnoticed.

The more symptomatic ones and the ones that are visually noticeable and stubborn tend to be the kind of mouth ulcers we deal with in our clinic.  

Yes, ouchie!!

To give you a bit of background; it is estimated that 9% of kids are affected by mouth ulcers.

Mouth ulcers are not as straight forward as you might think. What causes mouth ulcers? Read on to find out…..

Why does my child have mouth ulcers?

There are actually a wide range of potential causes. Anything from direct trauma to the area, infections, nutritional deficiencies, food sensitivities, underlying illnesses, autoimmune disease, and medication-induced.

A thorough investigation of :

  • what the ulcer/s look like
  • how many there tends to be
  • how long they have been around for
  • how long they take to heal
  • what other symptoms your child is experiencing
  • what was going on leading up to the first appearance of them
  • … this information can help pinpoint what might be at the bottom of it all.

Let’s take a look at some of the potential reasons for mouth ulcers.

Direct trauma?

First up, we have to rule out direct trauma to the area. This can include accidental biting of areas inside the mouth, being a bit too aggressive with brushing teeth, grinding teeth at night and catching the gum in between… Maybe your child has ill-fitting braces or they have stuck something sharp or hot in their mouth.

Food allergies or sensitivities?

Foods can also be a factor in both making it more likely to develop a mouth ulcer- things like chocolate, coffee, peanuts, almonds, cereals, and gluten-containing foods. There is also the potential for food allergies contributing to mouth ulcers; in particular, dairy.

Overconsuming acidic foods/ drinks such as tomatoes, pineapple, citrus,


If the child is suffering from a potential virus then there are a few ones that can have mouth ulcers as a symptom. It is more than likely obvious that your child is down with a virus such as HFM (hand, foot and mouth) or chicken pox. But, it may not be as easily distinguishable if they have Epstein-Barr Virus, Cytomegalovirus or Herpetic gingivostomatitis caused by the herpes simplex virus. Mouth ulcers have even been a feature of COVID-19.

Viral infections are self-limiting and generally benefit from topical relief of the ulcers and potential immune support to optimise recovery; depending on the immune strength of the child. Some kids seem to bounce back without much more than a short period of rest and recovery. Others who get knocked off their feet may need the extra TLC.

Nutritional deficiencies?

Deficiencies in certain nutrients can manifest on the skin. The typical ones we are concerned about when a child presents with recurrent mouth ulcers are iron and some of the B vitamins.

Correcting a deficiency needs to take into account potential underlying issues that may be getting in the way of digesting food and absorbing the nutrients.

We do need to consider underlying conditions that are causing the deficiencies. We have the mouth ulcers but we also have some other signs and symptoms.

Underlying health conditions?

Coeliac disease and Inflammatory bowel disease are two not so fantastic conditions we want to find out our child has but these do need to be ruled out when there are signs and symptoms consistent with them. Mouth ulcers are just one potential sign. We do want to see at least three things consistent with these conditions before we want to think about exploring them further. But they can be the first sign of something more serious going on. If there is a family history, it would definitely be worth ruling out. This is when you need to see a doctor as well as us.


Use of medications such as antibiotics have the potential to upset the gut and oral microbiome. The mouth is the first part of the

and many people may not know that the delicate balance of microbes in the mouth can get thrown out opening up gaps for overgrowths of unfavourable or pathogenic bugs.

Nourishing the microbiome back to balance by feeding the good guys and pushing out the bad ones can help put a stop to recurrent mouth ulcers.

Need support?

As you can see, there can be a number of reasons why your child is presenting with mouth ulcers. You can do a bit of detective work yourself. Get in touch with us today to see how we can help support the healing process and reduce the likelihood of reoccurring.

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