Introducing Allergens Safely & In Order: The Complete Guide for Hong Kong Parents (6m+)
For years, parents were told to delay allergens — peanuts until age three, eggs until one, fish "just to be safe". That guidance has been reversed by two decades of clinical evidence. The question for Hong Kong parents in 2026 is no longer whether to introduce allergens, but how to do it safely and in the right order.
This guide covers the top 9 allergens recognised by the Hong Kong Department of Health (FHS), the right introduction timeline, fish safety facts, the allergen trial method, and seven common myths — all grounded in real evidence. No guesswork.
What Are the Major Allergens?
The Hong Kong Department of Health (FHS) identifies nine major food allergens. All can be introduced from 6 months — one at a time, with 2–4 days between each new one so you can monitor for reactions.
* Dairy as an ingredient in food (yogurt, cheese, cooked milk in recipes) from 6m+. Whole cow's milk as a drink only from 12 months+.
When to Introduce Each Allergen
According to the Hong Kong FHS (updated March 2025) and the Baby-Friendly Hospital Initiative Hong Kong Association (BFHIHKA), allergens should be introduced alongside other complementary foods — from around 6 months, without deliberate delay. Dr. Agnes S.Y. Leung of CUHK states: "In regions where the prevalence of food allergy is not high, including Hong Kong, allergenic solids should be introduced without delay (under 12 months old)."
Begin with iron-rich foods and soft vegetables. You can introduce allergens at the same time — there is no need to wait for a "safe foods only" period first.
Introduce each new allergen in isolation, in the morning or at midday (not at dinner — so you can monitor reactions during waking hours). Wait 2–4 days before trying the next. FHS advises this spacing so that if a reaction occurs, you can identify the exact cause.
This is critical and often overlooked: once a food is tolerated, keep it in the diet regularly. The NHS and BFHIHKA both emphasise that consistency of exposure is what maintains tolerance. Stopping after introduction can allow sensitivity to redevelop.
If your baby has severe eczema, consult a paediatrician or allergist before introducing high-risk allergens like peanut and egg. BFHIHKA / Dr. Leung recommends specialist referral for this group. The goal is still early introduction — but under medical guidance.
Mercury & Fish: What Parents Actually Need to Know
The mercury concern is real — but it applies to a small number of large apex-predator fish. Most commonly eaten fish are completely safe for babies from 6 months, and the FDA/EPA have a clear tiered system to guide families.
The key rule: choose species from the FDA "Best Choice" or "Good Choice" tiers, and avoid the "Choices to Avoid" tier (shark, swordfish, king mackerel, bigeye tuna, tilefish). Fish is recommended by FHS for infants for its DHA and Vitamin D content.
Cook fish completely through until the flesh flakes easily and there is no translucency — never serve undercooked fish to an infant. Remove ALL bones before serving; run your fingers along every piece. For eggs: cook fully until both the white and yolk are completely set — no runny yolk, no soft white.
How to Try Each Allergen Safely
This is the FHS-recommended approach for introducing every new allergen. Follow it every single time, regardless of whether the food is "high risk" — consistency is what catches problems early.
Offer the new allergen at breakfast or lunch, never at dinner. If a reaction occurs, you want your baby awake and you alert — not asleep at 11pm. Introduce on a day when you are home and can observe for 2 hours after.
Start with a tiny amount — a quarter teaspoon of smooth thinned peanut butter mixed into porridge, one flake of cooked fish, a pea-sized piece of well-cooked egg. For peanut specifically: always use smooth peanut butter thinned with water or breast milk — never offer whole nuts (choking hazard).
FHS recommends waiting 2–4 days before introducing the next new allergen. This spacing — not 7 days — gives you enough time to spot a delayed reaction (rash, hives, vomiting) and attribute it clearly to the new food. You can keep offering tolerated foods while waiting.
Mild reactions (skin redness, a small hive, mild runny nose): note the food, contact your doctor, do not reintroduce without guidance — but this is not necessarily a permanent ban. Serious reactions (swelling of lips/face/throat, vomiting, difficulty breathing, pale/blue skin): call 999 immediately.
Never add salt or sugar to baby food under 12 months. Honey specifically carries the risk of infant botulism — a rare but serious bacterial illness — and must never be given to a baby under 12 months old under any circumstances.
When to See a Doctor
- Swelling of lips, face, tongue, or throat
- Difficulty breathing or wheezing
- Sudden vomiting and/or collapse
- Pale, blue, or floppy skin tone
- Loss of consciousness
- Hives or skin redness limited to a small area
- Mild runny nose or watery eyes after eating
- Loose stools 24–48 hours after a new food
- Persistent eczema flare after introduction
- Gagging that is frequent or worsening
Mild reaction does not mean permanent ban. Many mild reactions are transient sensitivities that can be managed with medical guidance. Your paediatrician will advise whether to try again and how. Do not make the decision to permanently avoid a food on your own.
7 Allergen Myths — Busted
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Sources Cited in This Guide
- Hong Kong Department of Health, Family Health Service (FHS) — Infant Feeding 6–12 Months Guide (Updated 03/2025): fhs.gov.hk
- Hong Kong Department of Health, FHS — Food Allergy Professional Newsletter: fhs.gov.hk
- Baby-Friendly Hospital Initiative Hong Kong Association (BFHIHKA) / Dr. Agnes S.Y. Leung, CUHK — Allergen Prevention Guidance (Dec 2023): babyfriendly.org.hk
- American Academy of Pediatrics (AAP) / Dr. Scott Sicherer MD FAAP — Early Introduction of Peanut-Based Foods to Prevent Allergies: healthychildren.org
- NHS UK — Food Allergies in Babies and Young Children (Updated Mar 2026): nhs.uk
- FDA / EPA — Advice About Eating Fish (2024): fda.gov
- MamiDaily HK — Baby Food Allergies: The 11 Major Allergens (2026): mamidaily.com
- LEAP Trial (Learning Early About Peanut Allergy) — 86% peanut allergy reduction with early introduction.
- PETIT Study (Prevention of Egg Allergy with Tiny Amount Intake) — 79% egg allergy reduction from 6-month introduction.
Last reviewed: June 2026. This article is for informational purposes only and does not substitute advice from your doctor, paediatrician, or registered dietitian. Always consult a qualified healthcare professional for individualised medical guidance.
