Introducing Allergens Safely
Evidence-based guide to introducing common allergens early and safely.
Introducing common allergens to your baby is one of the most important steps in the weaning process. Recent research has transformed our understanding of food allergies, showing that early introduction of allergens between six and twelve months actually reduces the risk of developing allergies. This guide provides evidence-based advice on when and how to introduce allergenic foods safely, helping you protect your baby's health while building a varied, nutritious diet.
The 9 Common Allergens
Nine foods account for approximately ninety percent of all food allergies. These are the foods you need to introduce deliberately and carefully during your baby's first year.
- Peanuts - One of the most common and potentially serious allergies
- Tree Nuts - Including almonds, cashews, walnuts, hazelnuts, pecans, pistachios
- Eggs - Particularly egg white, though whole eggs should be introduced
- Cow's Milk - As a food ingredient, not as a main drink before twelve months
- Wheat and Gluten - Found in bread, pasta, cereals, and many processed foods
- Soy - Found in soy milk, tofu, and many processed foods
- Fish - All types of finned fish
- Shellfish - Including prawns, crab, lobster, mussels
- Sesame - Seeds and tahini paste
How to Introduce Allergens Safely
Following these guidelines will help you introduce allergens safely while monitoring for any reactions.
One at a Time
Introduce only one new allergen every three to five days. This spacing allows you to identify which food caused a reaction if one occurs. If you introduce multiple allergens at once and your baby reacts, you won't know which food was responsible. Keep a simple diary noting which foods you've introduced and when.
Start with Small Amounts
Begin with a very small amount, approximately one-quarter of a teaspoon. If there's no reaction, you can gradually increase the amount over the next few days. By the end of the first week of introducing a new allergen, aim to offer a full portion as part of a meal. This gradual increase allows you to spot any reactions early with minimal exposure.
Timing Matters
Introduce new allergens early in the day, ideally at breakfast or lunch. This gives you the full day to monitor for any reactions. Avoid introducing new allergens at dinner time or before bed, as reactions typically occur within minutes to two hours of eating. Always introduce allergens at home rather than when you're out or traveling, so you can respond quickly if needed.
Preparation is Key
All allergens should be well-cooked when first introduced. Eggs must be cooked until both the white and yolk are solid. Fish and shellfish should be thoroughly cooked. Cooking can reduce the allergenic potential of some foods and makes them safer and easier to digest. Never offer raw or undercooked eggs, meat, or fish to babies.
Safe Forms for Babies
Nuts and seeds must never be given whole to babies or young children due to choking risk. Instead, offer them as smooth nut butters, ground into powder, or crushed and mixed into other foods. Peanut butter should be smooth, not crunchy, and thinned with breast milk, formula, or water to prevent choking. Whole nuts are a choking hazard until at least five years of age.
Practical Serving Ideas
| Allergen | How to Serve | Example |
|---|---|---|
| Peanuts | Smooth peanut butter thinned with milk or water | Mix 1/4 tsp into baby's porridge or yogurt |
| Tree Nuts | Ground into fine powder | Sprinkle ground almonds on porridge |
| Eggs | Well-cooked and mashed | Scrambled egg or mashed hard-boiled egg |
| Cow's Milk | In cooking or mixed with food | Add milk to mashed potatoes or baby cereal |
| Wheat/Gluten | Soft bread or cooked pasta | Toast fingers or well-cooked pasta shapes |
| Soy | Soft tofu or soy yogurt | Mashed silken tofu mixed with vegetables |
| Fish | Flaked, boneless, well-cooked | Salmon or cod mixed with mashed potato |
| Shellfish | Finely chopped, well-cooked | Finely chopped prawns in mild sauce |
| Sesame | Tahini paste or ground seeds | Thin tahini mixed into hummus or yogurt |
Recognizing Allergic Reactions
Most allergic reactions are mild and occur within minutes to two hours of eating the food. However, it's important to know the signs and when to seek help.
Mild to Moderate Reactions
These reactions require medical attention but are not immediately life-threatening. Contact your GP or call NHS 111 if your baby develops a rash or hives anywhere on the body, swelling of the lips, eyes, or face, vomiting or diarrhea shortly after eating, or persistent crying or distress. Take a photo of any rash, as it may have faded by the time you see a doctor. Note exactly what your baby ate and how much.
Severe Reactions (Anaphylaxis)
Anaphylaxis is a severe, potentially life-threatening allergic reaction that requires immediate emergency treatment. Call 999 immediately if your baby has difficulty breathing, wheezing or a persistent cough, swelling of the tongue or throat, becomes pale, floppy, or unconscious, or has blue lips or skin. If you have an adrenaline auto-injector (EpiPen), use it immediately while waiting for the ambulance. Lay baby flat unless they're having trouble breathing, in which case sit them upright.
It's important to distinguish between an allergic reaction and normal baby behavior. Not all rashes or vomiting are allergic reactions. Babies often have minor skin irritations, and vomiting can occur for many reasons. An allergic reaction typically involves multiple symptoms occurring together shortly after eating a specific food.
High-Risk Babies
Some babies have a higher risk of developing food allergies. This includes babies with moderate to severe eczema, existing food allergies, or a sibling with a peanut allergy. If your baby falls into any of these categories, you should still introduce allergens, but you may want to consult your GP or an allergist first, particularly before introducing peanuts and eggs.
Your doctor may recommend introducing these allergens in a supervised clinical setting, or they may simply provide guidance on doing it at home. Don't delay introduction without medical advice, as this could increase allergy risk. Most high-risk babies can still safely introduce allergens at home with appropriate precautions.
Continuing Allergen Exposure
Once you've successfully introduced an allergen, it's crucial to keep offering it regularly. Research shows that regular consumption maintains tolerance. Aim to include each allergen in your baby's diet two to three times per week. If you introduce peanuts successfully but then stop offering them for several months, your baby may lose tolerance and develop an allergy.
This doesn't mean every meal needs to include allergens, but make them a regular part of your baby's varied diet. Rotate through different allergens across the week. For example, offer eggs on Monday and Thursday, fish on Tuesday and Friday, and peanut butter on Wednesday and Saturday. This regular exposure helps maintain the tolerance you've worked to establish.