Children with upset stomachs


IMPORTANT The information provided is of a general nature and should not be used as a substitute for professional advice. If you think you may suffer from an allergic or other disease that requires attention, you should discuss it with your family doctor. The content of the information articles and all illustrations on this website remains the intellectual property of Dr Raymond Mullins and cannot be reproduced without written permission.

It is very common for young children to have bloating and diarrhoea and wind. Common things occur commonly and apart from gastroenteritis/infection, the following conditions can be considered if young children have these symptoms. Importantly, allergy testing is of no use in any of these conditions.

Toddler’s diarrhoea

This is a common condition of early childhood, where loose and smelly bowel motions may be seen, often containing undigested food. Excess intake of liquid or a diet high in fibre but low in fat and protein may be a contributor, as the immature gut may find it hard too digest and absorb too much food or liquid. Children continue to thrive and their nutrition if not affected. Cutting back on peas, corn, beans or foods high  in fibre like Weetbix and sugar and fructose and sorbitol can help and adding some food with fat like cheese or yoghurt can help.


Lactose intolerance

Lactose intolerance is an enzyme deficiency, more commonly present in those with an Asian background. It is present in roughly one in 30 people. Lactose is hard to digest and doesn't get absorbed and therefore ferments and causes bloating and wind retains fluid in the bowel to trigger diarrhoea. Small amounts of dairy products are tolerated but larger amounts triggered symptoms. Lactose free yoghurt and milk like Zymill from the supermarket will be tolerated. Modest amounts of ordinary yoghurt and hard cheese are also generally better tolerated than pure milk because the sugar lactose is bound up. Since food goes through the bowel within a few days, if lactose intolerance is present, sticking to a lactose free diet usually results in significant improvement within a week.


Fructose intolerance

Fructose is a naturally occurring simple sugar found in fruit, vegetables, and honey. Fructose

intolerance can occur in people with irritable bowel syndrome. Excessive fructose in food like apples, pears and juice can cause loose bowel motions in young children, often known as toddlers diarrhoea. By contrast, glucose is generally better tolerated. Small amounts are usually tolerated but larger amounts can trigger bloating, wind and nausea and diarrhoea. Essentially, there is not enough of the enzyme needed to break down the sugar fructose and so the sugar stays in the bowel and ferments and retains fluid inside the bowel triggering diarrhoea.


Fructans are made up of multiple fructose units linked in long chains. Wheat, in particular, has significant levels of fructans. Many vegetables contain fructans as well, such as artichokes, onion, garlic, asparagus, leeks and chicory.


Sorbitol or Sorbose is a sugar alcohol used as an artificial sweetener and found naturally in fruitsand fruit juices. It can also be found in many “diet foods” such as diet soft drinks, sugar-free chewing gum and sugar-free jelly/jam. Sorbitol often creates similar symptoms as fructose – especially when fructose and sorbitol are consumed together.

If fructose intolerance is suspected

Food normally goes in one end and out the other within a few days. If fructose or lactose (in dairy products) intolerance is suspected, then one can restrict foods high in fructose, fructans and sorbitol for a week to 10 days (with or without a or low lactose food diet too). One can then try challenges with high fructose or high lactose food separately for a few days at a time to see whether symptoms are triggered. If they are, then one can play around with diet to try to see whether dietary restrictions need to be very stringent or whether small amounts are tolerated. Importantly, the mechanism is not allergy and therefore allergy testing is not going to help. It is possible to measure the enzymes that digest lactose and fructose by doing an endoscopy and taking a sample of the upper gut, or doing s0-callled breath tests, but trials of dietary manipulation are usually easy to undertake.

High fructose food to avoid

Fruit –prunes, pears, cherries, peaches, apples, plums, pears, grapes, guava, pawpaw, quince persimmon, honeydew, grapes, dates and watermelon, as well as fruit juice made from the same type of food. Some low-calorie food like ice creams, lollies and biscuits or cereals can be sweetened with fructose or sorbitol.

Other – honey, coconut milk and coconut cream, food with added corn syrup.

Sucrose (cane sugar) is broken down during digestion into equal amounts of glucose and fructose, and may be tolerated in small amounts, but larger amounts will release high levels of fructose which can trigger symptoms.

High fructan foods to avoid

Inulin and Fructo-oligo-saccharides (FOS), both sources of fructans, are sometimes added to foods such as yoghurt.

Wheat has significant levels of fructans which may be poorly tolerated.

Many vegetables contain fructans as well, such as artichokes, onion, garlic, asparagus, leeks and chicory.

Low fructose food – generally tolerated

Most vegetables – although sometimes excessive tomatoes, corn, carrot or sweet potato can trigger symptoms.

Fruit – pineapple, strawberry, raspberry, blackberries, avocado, rhubarb and citrus fruit.


Delayed inflammatory reactions to food/non-IgE-mediated allergy

In young babies and occasionally infants, is common conditions such as proctocolitis or food induced enteropathy may occur. These are very uncommon compared to the above enzyme deficiencies. These are delayed inflammatory reactions where white cells come from the blood into the tissues and trigger bowel inflammation with regular exposure to food. Sometimes food passing through breastmilk can trigger the symptoms. The most common triggers are dairy and soy and occasionally other foods. If a young baby is unwell and has blood and mucus and very loose bowel motions, then proctocolitis can be suspected, in which case temporary restriction of dairy and soy can be considered. Symptoms usually disappear by the age of two years and trying small and increasing amounts every six months is appropriate. Coeliac disease is a different type of inflammatory reaction to food can cause diarrhoea, and is triggered by exposure to wheat and gluten containing food.


Sometimes investigation might be needed

If a child has failure to thrive and is not improving with dietary manipulation (which should be only undertaken with medical and dietetic supervision for a short period), and sometimes further investigation might be required.

Last reviewed 27 June 2020