For years, parents were told to delay allergenic foods. The advice has flipped. Current guidance suggests that introducing common allergens early and regularly — rather than avoiding them — may actually help reduce the risk of developing food allergies. Here's how to do it safely, and why keeping track matters so much.
When should I introduce allergens?
Most guidance now recommends introducing common allergenic foods from around 6 months, once your baby has started solids and tolerated a few first foods — not delaying them until later in life. Early, repeated exposure is the key idea.
If your baby has severe eczema, an existing food allergy, or a strong family history of allergies, talk to your pediatrician or an allergist before you begin. In some cases they may recommend introducing certain allergens earlier, or under medical guidance.
What are the common allergens?
Most food-allergic reactions in children are caused by a short list of foods. These are the ones worth introducing deliberately and tracking as you go:
Whole nuts are a choking hazard for babies and young children — always offer nuts as a smooth butter thinned with water, milk, or puree, never whole.
How to introduce an allergen, step by step
- Pick a calm day. Introduce a new allergen at home, earlier in the day — not right before bed — so you can watch your baby for a few hours afterward.
- Offer one allergen at a time. Start with a small amount of a single allergen. Don't introduce two new allergens on the same day — you want to know exactly what caused any reaction.
- Watch, then build up. If there's no reaction, gradually offer a bit more, and keep that food in your baby's diet regularly (a few times a week). Regular exposure is what helps maintain tolerance.
- Track it. Note the date, the food, and how your baby responded. If a reaction ever happens, this record is genuinely useful for you and your doctor.
If you introduce peanut and egg on the same afternoon and your baby reacts, you won't know which one to avoid. Spacing allergens out — and keeping a simple log — turns a scary guessing game into clear, actionable information.
What does a reaction look like?
Most reactions are mild, but it's important to know what to watch for. Mild signs can include:
- A few hives or a red, blotchy rash, often around the mouth
- Mild swelling of the lips
- An itchy mouth, some vomiting, or loose stool
If you notice mild symptoms, stop offering that food and contact your pediatrician for advice before trying it again.
Seek emergency help immediately (call your local emergency number) if your baby shows any signs of a severe allergic reaction (anaphylaxis): difficulty breathing, wheezing, swelling of the tongue or throat, sudden pale or floppy appearance, or widespread swelling. If your child has been prescribed an adrenaline auto-injector, use it and call for emergency help.
Keeping allergen introduction stress-free
The anxiety around allergens is real — but a system makes it manageable. When you can see at a glance which allergens your baby has safely tried, which are still to come, and when each was last offered, the whole process feels less like a minefield and more like a checklist you're steadily working through.
Keep reading: Starting solids: a complete guide · Iron-rich foods for babies
This article is for general information and isn't medical advice. Allergen introduction can carry risk for some babies — if your child has severe eczema, an existing allergy, or a family history of food allergies, speak to your pediatrician or an allergist before introducing allergenic foods. In an emergency, call your local emergency number.