Introducing allergens

Quick answer

Offer common allergens like peanut and egg from around 6 months, once your baby has started solids, but not before 4 months. Introduce one at a time, in a small amount and a safe form, and once your baby tolerates it, keep offering it regularly.

Why early, and why keep going

Waiting doesn't prevent food allergy. There's no evidence that holding back foods like peanut and egg beyond about 4 to 6 months helps, and delaying them may make an allergy more likely. Introducing them around 6 months, and then keeping them in your baby's diet regularly, may lower the chance of a food allergy developing.

Talk to your doctor first if…

your baby has severe eczema, or eczema that's hard to control
your baby has an egg allergy, has already had an allergic reaction to a food, or has another diagnosed food allergy

These babies have a higher chance of peanut allergy. Guidelines recommend they're checked by their pediatrician or an allergist, sometimes with allergy testing, before peanut is introduced, and early introduction (often around 4 to 6 months) matters most for them. Don't give the first peanut at home until your doctor has told you how. For most other babies, no allergy testing is needed before you start.

In the UK, the NHS also advises talking to your GP or health visitor first if your baby has any eczema, or if there's a family history of food allergy, eczema, asthma or hay fever.

How to offer a new allergen

Pick a day your baby is well, at home, when you can watch them for a couple of hours afterward.
Start with a small amount, mixed into a food your baby already eats.
Offer one new allergen at a time, and wait a few days before the next one, so you can tell what caused any reaction.
If there's no reaction, keep offering it regularly as part of your baby's usual diet.

The 9 common allergens, and a safe first form

These are the 9 major food allergens in the US. UK labeling lists 14, including other cereals with gluten, celery, mustard and lupin.

Peanut
Smooth peanut butter thinned with water, breast milk or formula, or stirred into another food. Peanut powder mixed into food works too.
Never whole or chopped peanuts, or spoonfuls of thick peanut butter.
Egg
Full guide
Well-cooked egg: hard-boiled and mashed or cut into strips, a fully cooked omelet, or egg baked into food.
No raw or runny egg.No raw or runny egg, unless it has the British Lion stamp (see the egg page).No raw or runny egg.
Milk (dairy)
Plain, full-fat yogurt; pasteurized hard cheese like mild cheddar, grated or in thin slices; cottage cheese or cream cheese; or cow's milk used in cooking.
Not as a drink until 12 months. No chunks of cheese, and no brie, camembert or soft blue cheese.
Wheat
Soft wheat foods: well-cooked pasta, soft toast strips, or wheat infant cereal.
No whole wheat kernels, or bread and crackers with whole seeds or nuts.
Soy
Soft tofu strips or mashed tofu, or plain soy yogurt.
Fish
Full guide
Well-cooked fish, flaked or in strips, checked carefully for small bones. Choose fish that is low in mercury, like salmon.
No raw fish (sushi, poke, ceviche).
Shellfish
Fully cooked shrimp, finely chopped or mashed into another food.
Never raw or lightly cooked.
Tree nuts
Smooth almond or cashew butter, thinned, or finely ground nuts stirred into food.
Never whole or chopped nuts, or spoonfuls of thick nut butter.
Sesame
Tahini thinned or stirred into food, or homemade hummus with no added salt, or finely ground seeds.
No whole seeds sprinkled on top.

Signs of an allergic reaction

Reactions usually start within minutes of eating, but can take up to 2 hours. Some, like cow's milk allergy, can take up to 3 days.

Mild to moderate

Hives or a red, itchy rash, especially around the mouth
Mild puffiness of the face or around the eyes
Vomiting once, tummy pain or diarrhea
Sneezing or a runny nose
Eczema getting worse

If it's only one of these, stop offering the food, stay with your baby and watch them closely for the next couple of hours, and call your pediatrician before you try it again. If it gets worse, or signs show up in more than one part of the body at once, treat it as severe (below). Don't cut out a major food like milk for good on your own: ask your doctor, who may refer you to a dietitian.

Severe (anaphylaxis): call 911999your local emergency number (such as 112 in Europe or 000 in Australia)

Trouble breathing, wheezing, or a cough that won't stop
Lips or mouth that suddenly swell
Swelling of the tongue or throat, a hoarse cry, drooling or trouble swallowing
Turning pale or floppy, or becoming very sleepy or unresponsive
Signs in more than one part of the body at once, such as hives with vomiting

If your baby has been prescribed an epinephrine auto-injector, use it right away, then call for help. If you don't have one, call straight away. If you're alone with your baby, use the auto-injector first if they have one, then call on speaker; don't leave your baby to find a phone. Keep your baby lying down, not standing or walking: on their side if they're vomiting, with head and shoulders a little raised if breathing is hard. Go to the emergency room even if they seem better, because symptoms can come back.

Introducing allergens

Quick answer

Why early, and why keep going

Talk to your doctor first if…

How to offer a new allergen

The 9 common allergens, and a safe first form

Peanut

Egg

Milk (dairy)

Wheat

Soy

Fish

Shellfish

Tree nuts

Sesame

Signs of an allergic reaction

Mild to moderate

Severe (anaphylaxis): call 911999your local emergency number (such as 112 in Europe or 000 in Australia)

Sources