The most common cause of diarrhoea in children is a viral infection, such as in gastroenteritis (sometimes called ‘gastro’). Like vomiting, diarrhoea can go along with many infections, both bacterial and viral. Less commonly, it might be a sign of a more serious illness such as appendicitis.
Chronic or persistent diarrhoea might follow a bout of gastroenteritis. In this case, the diarrhoea might be caused by lactose intolerance. During a bout of gastro, the lining of the bowel wall is temporarily damaged, so that it can’t absorb complex sugars, including lactose, which is a part of milk. Lactose intolerance causes watery, often sweet-smelling diarrhoea, which might burn your child’s bottom.
Other causes of chronic diarrhoea include Giardia (a parasitic infection), coeliac disease, irritable bowel syndrome in older children, and other less common conditions. Some toddlers with chronic diarrhoea might be drinking too much fruit juice.
In many toddlers, no cause for the diarrhoea is found. This is called toddler’s diarrhoea.
Your child will have large, runny, frequent or watery poos. The colour of the poo might vary from brown to green, and the smell can be really nasty.
Diarrhoea might also be associated with tummy cramps or pain.
The most serious problem associated with diarrhoea is the possibility of it leading to dehydration.
When to see your doctor
It’s always a good idea to see your doctor if your child has diarrhoea, especially if your child is under three months old.
If the diarrhoea is caused by a specific virus, germ or parasite, a test of your child’s poo can reveal which of these is the problem.
The most important thing when treating diarrhoea is to make sure that your child has enough to drink. Give your child only small drinks, but give drinks often. The best fluid to use is an oral rehydration fluid such as Gastrolyte, which can be bought over the counter from the chemist. Make sure that you make up the liquid carefully according to the instructions on the packet.
If you can’t get Gastrolyte, you can use diluted lemonade or fruit juice. Use one part of lemonade or juice to four parts of water. An alternative is to mix one level teaspoon of sugar in 120 ml of water. Full-strength lemonade or fruit juice might make the diarrhoea worse and can be harmful.
If you have a young breastfed baby, continue breastfeeding but offer extra oral rehydration fluid between feeds. If your baby is bottle-fed, give him oral rehydration fluid for the first 24 hours and then reintroduce full-strength milk, but give extra oral rehydration fluids between feeds.
Your child might refuse food to start with. But if your child’s hungry, you can give her food at the same time as oral rehydration. It’s generally best to start with bland foods such as plain biscuits, bread, rice, potato or jelly. Other foods can be added gradually.
Don’t treat your child with antidiarrhoeal agents. There’s no evidence to show that these treatments change or improve symptoms. Also, even if your child has diarrhoea caused by a bacterial infection, antibiotics aren’t normally necessary. In every case, your doctor will advise you about the best treatment option for your child.
If your child is very dehydrated, he might need fluids to be given intravenously (directly into the vein) or through a tube that goes up his nose and into his stomach. In this case, he’ll have to go into hospital.
For diarrhoea associated with lactose intolerance, use a lactose-free milk (unless your child is still breastfed) until the diarrhoea improves. This condition usually sorts itself out within a few weeks as the lining of the bowel wall heals.