The weaning series Part 2 of 3
When to introduce allergens to your baby: the 3-day rule myth, and what the HSE actually says
If you've read that you need to wait three days between every new food before trying another, you are not alone. You can stop worrying about it.
IN SHORT:
Introducing allergens is simpler than it feels, and most babies do just fine.
- Start around 6 months, as soon as you begin weaning.
- The "3-day rule" is not what the HSE recommends. You can introduce more than one allergen in the same week.
- Give each new allergen about 3 times in the same week, starting with a small amount.
- If your baby has eczema, it's even more important not to delay. They're at higher risk of food allergy.
- Know the signs of a reaction, and speak to your GP if one happens.
Is it too late to introduce allergens at 7 or 8 months?
No, and there's no reason to feel behind. It's a common worry once solids are already well underway and you realise you haven't tried egg or peanut yet.
The HSE recommends introducing common allergens as soon as you start weaning, around 6 months. Waiting longer may increase your baby's risk of developing an allergy.
If your baby is a bit older and hasn't had these foods yet, the right time is now, not later. There's no need to wait for a "better" moment. Starting today is the better moment.
What is the "3-day rule," and do you actually need to follow it?
You might have read that you should wait three days between each new allergen, to be safe. This idea is common online, but it isn't what the HSE recommends. It can also make things feel far more complicated than they need to be.
What the HSE actually says: introduce each new food one at a time, and give it to your baby around 3 times in the same week. You can introduce other allergens in that same week too. You don't need to space them out by days in between.
For example, in one week, you could give your baby a taste of peanut butter, then egg a couple of days later.
Which foods should you introduce, and how much?
The main allergens to introduce during weaning are:
- dairy
- egg
- peanut
- fish and shellfish
- sesame
- tree nuts (such as almond, cashew, hazelnut and walnut)
- wheat
Two that parents often ask about specifically:
- Peanut: a heaped teaspoon of smooth peanut butter (no added sugar or salt), or 3 to 4 finely crushed peanuts.
- Egg: a mashed hard-boiled egg.
Start with a small amount, around a teaspoon, then build up to a normal portion over time if your baby doesn't react.
One important safety point: never give a baby whole nuts or peanuts. They are a choking hazard at this age. Always use a smooth nut butter, or nuts that are very finely ground or crushed, instead.
Does eczema change anything?
Yes. Babies with eczema have a higher risk of food allergy. That makes it even more important not to delay introducing allergens.
There is one extra thing to watch for: try to keep the food off their skin. This matters if they have eczema on their hands or face, since food can irritate the area.
How do you know if it's a reaction, and what do you do?
Most babies try these foods with no problem at all. If a reaction does happen, it's usually one of two types.
An immediate reaction shows up within minutes, up to about 2 hours. It can include a sudden rash or swelling of the lips or face.
A delayed reaction takes longer to appear, from 2 up to 24 hours. It usually shows up as tummy symptoms, such as vomiting or diarrhoea.
If you think your baby has had a mild immediate reaction, speak to your GP before giving them that food again. If you're not sure what you're seeing, or you're worried, your GP or public health nurse can help you figure out the next step.
Note: a reaction to a food you've just introduced is different from a reaction to infant formula. If you think your baby might be reacting to their formula rather than to a food, don't switch formula yourself. Speak to your GP or public health nurse first.
We have separate pieces on the other early feeding basics: when to start weaning, and the best iron-rich first foods.
When should you call 999 or 112?
Call 999 or 112 straight away after any of these signs: difficulty breathing, or swelling of the tongue or throat. Also call if your baby suddenly becomes pale, floppy, or unresponsive. These are signs of a severe allergic reaction and need emergency care.
For anything less urgent, but that still worries you, contact your GP or public health nurse.
Sources of information: