June 29, 2018


By the time they turn one, half of Australian babies have had a course of antibiotics.

Penelope Bryant, Murdoch Childrens Research Institute; Cheryl Anne Jones, University of Melbourne; David Burgner, Murdoch Childrens Research Institute, and Nigel Curtis, Murdoch Childrens Research Institute

Half of Australian infants have received at least one course of antibiotics by their first birthday. This is one of the highest rates of antibiotic use in the world.

Although antibiotics are effective and potentially life-saving for bacterial infections in children, they are often prescribed for viral infections, for which they are ineffective.

Unnecessary antibiotics expose individual children to potential side effects, including diarrhoea, vomiting, rashes and allergic reactions.

The overuse of antibiotics also increases the risk of bacterial resistance in the wider community. This is when commonly used antibiotics become ineffective against some bacteria, making it difficult, or even impossible, to treat some infections.

Read more:
Recent death from resistant bug won’t be the last

Researchers are also beginning to realise there may be additional long-term health harms from antibiotic exposure in early life and before birth, including an increased risk of infection, obesity and asthma.

At the moment, most bacteria that cause childhood infections in Australia respond well to antibiotics. But this is likely to change, unless we use antibiotics more carefully.

The role of gut bacteria

We have vast numbers of bacteria in our gut, as well as viruses, fungi and other organisms. This microbial community is collectively known as the microbiome.

Our microbiome is essential for normal health and development and has been linked to an ever-growing list of health outcomes such as mental health, immunity, obesity, heart disease and cancer.

An infant’s first major contact with bacteria and other microbes occurs at birth. Babies born vaginally acquire their initial microbiome from the birth canal and gut. Those delivered by caesarean section are more likely to acquire bugs from their mother’s skin and the hospital.

Antibiotics during pregnancy can alter the mother’s microbiome and therefore the microbial profile her baby acquires.

Antibiotics kill off not only the bacteria causing the infection, but also bacteria of the microbiome, including those that are beneficial. The resulting imbalance of the microbiome is known as dysbiosis.

The baby’s early microbiome, acquired from the mother at delivery, “educates” the infant’s developing immune system in the first weeks and months of life.

Antibiotics in pregnancy can alter the mother’s and therefore the baby’s microbiome, affecting early immune responses. This may increase the risk of infection in childhood.

Read more:
Gut instinct: how the way you’re born and fed affect your immune system

In a recent Danish study, a mother’s exposure to antibiotics in pregnancy was associated with increased risk her child would develop a severe infection (requiring hospital admission) in the first six years of life.

The increase in risk was greatest among children whose mothers were prescribed more antibiotics and who received them closer to delivery.

There was also some evidence the risk was higher in those delivering vaginally.

This suggests antibiotics affect the mother’s microbiome, with downstream effects for the offspring. Other genetic and environmental factors shared between mother and child are also likely to play a role.


Antibiotics are widely used in meat production as a growth promoter. An estimated 80% of all antibiotic use is in animals. Much of their effect is via the livestock’s microbiome, which has a major role in metabolism and energy harvesting.

Antibiotics promote growth in livestock.
Syda Productions/Shutterstock

Antibiotics may also play a similar role in promoting growth in humans. There is some evidence antibiotic exposure in pregnancy is associated with increased birth weight and obesity in early life. But large studies are needed to account for the other important factors that may also contribute.

The association between antibiotics in early childhood and obesity is clearer. Antibiotic exposure within the first year of life is associated with a 10-15% increased risk of obesity, although the importance of the type and timing of antibiotics is less well understood.


Childhood asthma has increased in parallel with antibiotic use, leading researchers to investigate a link.

Observational studies have shown an association between antibiotic use in pregnancy or infancy and later risk of asthma. This supports the concept of antibiotic-induced dysbiosis (imbalance of bacteria) and the effect on the immune system.

Read more:
Healthy guts are swarming with bugs, so what do they do?

A large population-based Swedish study, however, found the link between asthma and antibiotics was largely attributable to a number of other factors, including respiratory infections contributing to asthma and unrecognised symptoms of asthma being inappropriately treated with antibiotics.

But other studies have found these factors don’t completely explain away the link between antibiotic use and asthma. A better understanding of the role of the microbiome in the development of asthma will help clarify the contribution of antibiotics.

The science is unclear about the link between antibiotics and asthma.
D K Grove/Shutterstock

Other links

Antibiotic use in early childhood, and particularly the first 12 months of life, is linked to gastrointestinal diseases such as Crohn’s and coeliac disease. The exact risk is difficult to quantify, but children receiving over seven courses of antibiotics were reported to be at a seven-fold risk of Crohn’s disease.

Other childhood inflammatory diseases, including juvenile idiopathic arthritis have shown a similar association.

However, as with asthma, because these are observational studies, the finding of an association does not prove causation: it’s possible these children were given antibiotics for symptoms of unrecognised gastrointestinal or inflammatory disease, or for an infection.

Finally, antibiotic use in early adulthood is associated with bowel cancer. The risk increases with more courses of antibiotic. Whether childhood antibiotic use is associated with adult bowel cancer risk has yet to be studied.

Read more:
We know _why_ bacteria become resistant to antibiotics, but _how_ does this actually happen?

Antibiotics have their place

Antibiotics are one of the most important medical innovations and save lives when used appropriately. But inappropriate use leads to potentially untreatable resistant infections and long-term health problems in children and adults.

The ConversationA recent assessment predicted that without restrictions, global antibiotic use will increase three-fold by 2030. Unless we all work together to reduce antibiotic overuse, we could be assigning our children to a future of chronic ill health. Too much too young underappreciated long-term adverse effects of early antibiotic exposure

Penelope Bryant, Consultant in Paediatric Infectious Diseases and General Paediatrics, Murdoch Childrens Research Institute; Cheryl Anne Jones, Professor of Paediatrics, University of Melbourne; David Burgner, Clinician and Scientist, Murdoch Childrens Research Institute, and Nigel Curtis, Professor of Paediatric Infectious Diseases, Murdoch Childrens Research Institute

This article was originally published on The Conversation. Read the original article.

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  • I was lucky and didnt need any antibiotics for my young one


  • I was told my teeth are discoloured from the antibiotics given to me when I was 18 months old. Hard to think this but reading this maybe it is true, so why did my adult teeth have the same problem.


  • In some ways I am glad I am an older mum – GP’s in my day hardly ever prescribed anti-biotics if they didn’t have to do so and I doubt any of my children got them before they went to school.


  • Our GP only prescribes antibiotics if he is sure they are needed. I had quite a few doses due to constant bouts of chronic tonsillitis. I often got ear infections at the same time and my ear would discharge yellow “gunk”. I had my tonsils out when I was 6 y.o. I have a niece who became delirious during a bout of tonsillitis, one of many times she had it. She had her tonsils removed when she was 5 y.o. just after she started school. My brother got tonsillitis every time he got a new tooth – including wisdom teeth. He was very sick when he had his removed as an adult and was almost re-admitted to hospital a few days later as his throat was so sore he gagged when he tried to swallow.A cousin of mine her constant tonsillitis infection poisoned her bloodstream and she came close to passing away. All those definitely needed antibiotics, especially if bouts were close together.


  • I trust my doctor with the information he gives me concerning antibiotics.


  • It’s so important to have a good GP, particularly for new parents who are learning to trust their instincts. I was one of those parents! If I thought something may be in the chest I would always take our Punks to check, just to be safe. Not every week, but maybe 3 times in their first year? My GP was always patient with me, and always only prescribes as a last resort, which didn’t happen in their first year anyway. But she still also always asks about my emotional health to make sure I am getting the support I need. She’s tops!


  • Really insightful. I’m lucky to have a family gp I trust to know what’s best for my bub


  • Thank you for the article, it was very informative and insightful. I find that there are quite a few doctors these days who are very quick to give you antibiotics. Like a couple of years back I was I’ll and the doctors prescribed me two roundabout of antibiotics and I didn’t get any better. It wasn’t until I went to a different practice they fully assessed me and found out I had pneumonia. But I try to only take antibiotics when I really need them.


  • Thanks for this good article, my son was very sick for a year, in and out of hospital and on large doses of antibiotics, the result ended up being leaky gut syndrome from all the antibiotics. I’m grateful he survived but at age 24 now, he still manages the results of the damage to his gut.
    As an adult, I’ve had the same thing happen to me from several doses of pneumonia and the large doses of antibiotics given to me which were necessary.
    In our cases it was necessary but the results to the gut are quite devastating. Always question if its absolutely necessary to need antibiotics, you can build up a resistance to them. Probiotics are a huge blessing , especially getting the right advice in using them right, mixing the strains you use each time or they’re ineffective. Probiotics plus a good GP and nutritionist who work with functional medicine as well as a good knowledge of complimentary medicine got us back to good health.


  • Doctors should no better than to prescribe antibiotics for a virus. Bottom line for any medication is only use it if you really need it.


  • I really do not understand how doctors are prescribing antibiotics for viruses? Antibiotics are needed when one has a bacterial infection or virus and sickness is severe. And I would expect doctors to know when to use them and when not.


  • I guess the bottom line is don’t use if you don’t have to.


  • Gosh, I’m pretty sure my grandson had a couple of courses of antibiotics by the time he was 1, thanks to starting childcare when he was only 5 months old


  • I’m so glad my son is almost 5 and never needed antibiotics. Most doctors prescribe them if you ask for them no matter whether you need them or not.


  • Dr’s need to be more accountable for what they prescribe.


  • I can honestly say between my four kids only one of them has required antibiotics. However as an adult I almost always walk away with a script for them seems very unnecessary.


  • We have very rarely used antibiotics.

    • It is always considered a last option by our GP.


  • Of my 3 girls, only 1 had to have antibiotics before she turned 1. But she had been unwell for weeks and in and out of hospital.

    Nothing since.

    I will even hold off on panadol unless it becomes really necessary. I wasnt aware of all the other risks though. For me it was about not building a tolerance.


  • My daughter got her first antibiotics when she was 3 years old. I’m glad there was no need earlier. And I never took antibiotics while pregnant. Antibiotics are often prescribed too easily. We should be aware of the bad effects they can have.


  • So basically, use caution but don’t panic.


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