Sunday, March 25, 2012

Why kids always have colds and snotty noses.

My cousin wrote to me recently saying that she was worried that her 17 month old son gets so many coughs and colds. So, I thought I'd write a blog busting some of the myths surrounding children and infection.

The first thing to say is that children get ill...lots. Mostly coughs, colds and snotty noses, with the occasionally vomiting and/or diarrhoea bug thrown in for variety. As upsetting as it is, this is all part of their immune systems maturing and learning to cope on their own. When they are born, they borrow an immune system from their mother. They have lots of antibodies (things that fight infection) swimming round their bodies. Antibodies can recognise specific illnesses if they have been exposed to them before (which is how vaccinations work). Because the mother's immune system is mature, i.e. has seen lots of bugs, the baby has help fighting off illnesses. If they are breast fed, this affect is increased because there are antibodies in breast milk.

As the baby gets older, the maternal antibodies wear off and the baby starts to make them for themselves. However, this doesn't happen overnight so young children are more vulnerable than adults to infections. Each time they get an illness or a bug, their immune system increases its ability to recognise things as bugs. However, there are so many bugs around that just as they are getting over one, another comes along and they have to start over again. (Sometimes it feels as if a child has been ill with the same bug for weeks and weeks, but probably it is several different bugs in a row.)

Children are 'allowed' to have (as a rule of thumb) 10 coughs and colds a year before a doctor would even consider doing tests to see if there were any other problems. (And even then the doctors wouldn't really get excited unless they had 'significant' illnesses, for example, needing to be admitted to hospital.) Given that most of these 10 coughs and colds occur in the winter months, it can feel like your child has a snotty nose all winter.

Children who are exposed to more bugs (go to nursery or have older siblings in nursery or school) will get ill more often. Washing hands is a very good way of preventing illnesses as a lot of bugs are spread by touch. 

The (nearly) last thing to point out is that colds are viral infections. Most infections are caused by bugs that are either viruses or bacteria (fungi can also cause infections.) Antibiotics only work on bacteria, they don't do anything to viruses. (It is possible to get antiviral medicines, but generally they are used for very severe infections.) The vast majority of coughs, colds and tonsillitis are causes by viruses. Antibiotics won't help at all. So mostly children don't need antibiotics when they have coughs, colds and tonsillitis. (If they have 'bactierial tonsilitis' they will benefit from antibiotics.)

Finally, children who have asthma may be more affected by coughs and colds because it can trigger the asthma. If you are worried about your child's breathing when they have a cold, you should go and see your doctor. 

Quite a lot of information in one blog but I hope it has given you some insight into why children always have snotty noses.

Check out for more information on breathing problems and fever.


  1. I think your piece drastically under explains the role of maternal antibodies via breastmilk - "borrowing an immune system", is rather misleading, no BM, hardly any SIgA and the immune system is left exposed and vulnerable.

    1. The 'borrowing' an immune system refers to when the child is born. All children are born with maternal antibodies which normally helps them fight infection (although sometimes can lead to illness in the child.) These are mostly IgG. I only mentioned as an aside that this affect is enhanced by breastfeeding.

  2. Also, persistent running noses can be significant in terms of allergy - so a child with a year-round rhinitis and post-nasal drip with or without asthma symptoms, eczema and seasonal symptoms should be considered a part of a differential diagnosis, especially where there is a history of allergy in the parents, or pets etc?