Can Allergies Be Prevented? What the Evidence Says
If you have a family history of allergy, or you’re expecting a baby, it’s natural to wonder whether there’s anything you can do to reduce the risk. There’s a lot of advice out there — some of it helpful, much of it not well supported by evidence. Here’s a clear-eyed look at what the research actually shows.
Pregnancy and diet
A common instinct is to avoid peanuts, eggs, dairy, and other allergy-causing foods during pregnancy, just in case. The evidence, however, doesn’t support this. Restricting common allergens from a pregnant mother’s diet has not been shown to reduce the likelihood of a child developing food allergies — and it has been linked to poor weight gain in babies.
Restricted diets during pregnancy are not recommended. Eating a varied, nutritious diet is better for both mother and baby.
Breastfeeding and diet
The same applies during breastfeeding. Studies have not found that excluding common allergens from a breastfeeding mother’s diet reduces the chance of her child developing food allergies. Restricted diets while breastfeeding are not recommended either.
Introducing solid foods
This is one area where timing genuinely does matter — and where the guidance has shifted significantly in recent years.
Solid foods should be introduced at around six months of age (not before four months), while ideally continuing to breastfeed. The key message is that common allergy-causing foods should be introduced before 12 months of age — not avoided. Research in babies at high risk of allergy has shown that early introduction of these foods actually reduces the chance of developing a food allergy, rather than increasing it.
Waiting until after 12 months to introduce foods like peanut, egg, and fish is no longer recommended. If your child has eczema or a known food allergy and you’re unsure how to approach introduction of allergenic foods, speak with your GP allergist or immunologist before proceeding.
The reason solid foods shouldn’t start before four months relates to development — a baby’s digestive system, and their ability to chew and swallow, simply aren’t ready. Early introduction at this stage has also been associated with higher rates of food allergy and eczema in at-risk infants.
What if my child already has a food allergy?
If you suspect your child has reacted to a food, speak with your doctor before introducing that food again. Don’t attempt a reintroduction at home without guidance.
For children with confirmed cow’s milk or soy allergy, special formula can be prescribed. Food restrictions should always be discussed and supervised by a doctor, and a referral to a dietitian is often helpful to ensure your child’s nutritional needs are still being met.
Soy or goat’s milk formula — a safer choice?
No. Research has not shown that soy milk or goat’s milk formula reduces the risk of food allergy in children compared to standard cow’s milk formula. If your child has a diagnosed allergy to cow’s milk or soy, your doctor can advise on appropriate alternatives.
Should I get rid of my pet?
Not unless someone in the household is already allergic to the pet and experiencing symptoms from it. There is no evidence that removing a pet pre-emptively — before any allergy has developed — reduces the risk of a child developing animal allergy. If a family member is already symptomatic, that’s a different conversation, and we cover that in more detail on our pet allergy page.
Will dust mite avoidance prevent allergy?
Unless someone in the household is already allergic to dust mites, there is no convincing evidence that dust mite reduction measures lower the risk of allergy or asthma developing in the first place. These measures are most useful as a management strategy once an allergy has already been confirmed.
Fish oil supplements
Despite some earlier optimism, there is currently no convincing evidence that taking fish oil supplements during pregnancy significantly reduces the risk of allergy in children.
Probiotics
Probiotics are not currently recommended for allergy prevention. The research is genuinely mixed — some studies have found a modest protective effect against eczema, while others have found no benefit for allergic disease overall. Further research is needed before probiotics can be recommended as a prevention strategy.
Can allergen immunotherapy help prevent allergy from developing?
Allergen immunotherapy (desensitisation) is currently used to treat established environmental allergies — not to prevent them from developing in the first place. However, there is emerging and encouraging evidence that treating children who have allergic rhinitis (hay fever) with immunotherapy may reduce the risk of them developing asthma, or becoming sensitive to additional allergens, later in life. This is an active area of research and one we follow closely.
You can read more about allergen immunotherapy on our AIT page.
The bottom line
Allergy prevention is genuinely complex, and there are no guaranteed strategies. What is clear is that some widely held beliefs — avoiding allergens during pregnancy, delaying introduction of foods, switching to alternative formulas — are not supported by evidence and can sometimes do more harm than good.
If you have concerns about allergy risk in your child or want guidance on the best approach for your family’s situation, our team of immunologists and GP allergists at Austral Allergy is here to help.
We see patients across our Canberra and Adelaide clinics and welcome you to arrange and appointment https://canberraallergy.com.au/
Clinics will soon be coming to Melbourne and the Northern Rivers
https://www.allergy.org.au/images/pc/ASCIA_PC_Allergy_Prevention_FAQ_2024.pdf