- What's happening
- Introducing common allergens early and keeping them in the diet builds and maintains tolerance.
- What helps
- One at a time, earlier in the day, age-appropriate forms, regular rotation.
- When to get help
- Hives, swelling, repeated vomiting, breathing changes — 999 for anaphylaxis.
- One tiny next step
- Pick one allergen to introduce this week — write the day on the calendar.
What's going on?
Current UK and international guidance is clear: from around 6 months, common allergenic foods should be introduced early — not avoided. Delaying introduction past 12 months increases, rather than decreases, the chance of an allergy developing.
The 'big 8' allergens are: peanut, tree nuts, cooked egg, dairy, wheat, soya, fish/shellfish, and sesame. They should be introduced in age-appropriate forms — never whole nuts or large lumps — and one at a time so a reaction can be linked to the food that caused it.
Most babies have no reaction to allergen introduction. When reactions happen, they are usually mild (rash, mild GI upset). Serious reactions are much less common, but you should know what to look for and what to do.
Common signs and symptoms
Very common
- No reaction — most babies tolerate allergens.
- A mild rash around the mouth (often from food touching, not actual allergy).
- Mild GI upset (a looser stool, a bit of vomit).
Less common
- Hives across the body.
- Swelling of lips, face or eyes.
- Repeated vomiting shortly after a feed.
Symptoms within minutes to an hour are 'immediate' reactions (IgE). Symptoms over hours to days are 'delayed' (non-IgE). Both are real.
Is this normal?
Most babies will not react to most allergens.
A small reaction does not always mean a serious allergy — but it does mean you should pause and speak to a GP before continuing that food.
Once a food is tolerated, keep offering it regularly (at least weekly). Stopping after one good experience can undo the tolerance.
Practical things that help
Offer a small amount earlier in the day
You can watch for any reaction over the next few hours while everyone is awake.
Introduce one new allergen at a time
If a reaction happens, you know what caused it.
Use age-appropriate forms
Smooth peanut butter mixed into yoghurt; fully cooked egg; flaked fish carefully checked for bones. Never whole nuts under 5.
Keep tolerated allergens in regular rotation
Regular exposure maintains tolerance. Once is not enough.
Discuss a plan with your GP first if there is a family history of severe allergy or your baby has significant eczema
Higher-risk babies may benefit from allergy team input before introduction.
What can accidentally make it harder?
Avoiding allergens 'just in case'
Avoidance increases, rather than decreases, allergy risk.
Trying multiple new allergens at once
If something reacts, you can't tell which food caused it.
Trying once and stopping
Tolerance fades without regular exposure.
These are gentle observations, not blame. None of us avoid all of them all of the time.
What should I say?
- “Little bit today. Little bit again next week.”
- “We keep it in, even if it's only a tiny amount.”
Red flags and when to seek help
Worth an assessment
- Hives or mild swelling after a specific food — pause and speak to your GP before trying again.
- Eczema that flares with feeds.
Urgent — same day
- Repeated vomiting after a food.
- Persistent rash after a feed.
Emergency — call 999
- Difficulty breathing, swelling of the lips/face/tongue, collapse — call 999.
- Any sign of anaphylaxis — call 999 immediately.
GPs can refer to a paediatric allergy team. Babies with significant eczema or a family history of severe allergy may benefit from this referral before introducing allergens.
If your child is seriously unwell or in danger, get help now.
Common myths
- Delaying allergens does not protect against allergy — it does the opposite.
- A red ring around the mouth from food touching is not the same as a food allergy.
One tiny next step
Pick one allergen to introduce this week — write the day on the calendar.
Note what you triedTalk this through
Ask Little Humans about allergens