If you had a baby ten years ago and you are having another one now, the allergen advice you were given the first time is probably the opposite of the advice you will get today. That reversal is real, it is well documented, and it is why so many parents feel unsure about when to offer peanut butter for the first time.
One note before anything else: this is general information for parents, not medical advice. Every clinical statement here is summarized from the American Academy of Pediatrics, and every source is linked at the end. We design reusable feeding and tracking charts for families, so we write from that vantage point rather than a clinical one. Your pediatrician knows your baby's history, and the allergen conversation is one worth having with them directly.
When should you introduce allergens to your baby?
For most babies, common allergens can be offered from around six months, once your baby is already handling other solid foods. The AAP is direct about the old advice, stating that there is no evidence that waiting to introduce baby-safe (soft) foods, such as eggs, dairy, soy, peanut products or fish, beyond 4 to 6 months of age prevents food allergy.
The practical sequence most families follow is to start solids with a few simple low-allergy foods, confirm that eating is going well, and then begin working allergens in. That usually means your baby has already had infant cereal, a vegetable or two, and some fruit before the first allergen appears.
Readiness for solids in general comes first. If you are not yet sure your baby is there, the developmental signs are covered in signs your baby is ready for solids. Allergens are a step that comes after that, not instead of it.
Which foods count as common allergens?
Nine foods account for the large majority of childhood food allergies. Most babies will meet all of them within a couple of months of starting solids.
| Allergen | A common first form |
|---|---|
| Peanut | Smooth peanut butter thinned into puree, yogurt or cereal |
| Egg | About one third of a well-cooked egg, mashed |
| Dairy | Plain whole-milk yogurt |
| Tree nuts | Cashew or almond butter, thinned the same way as peanut |
| Sesame | Tahini, thinned into puree |
| Wheat | Iron-fortified wheat infant cereal |
| Soy | Soft tofu, mashed |
| Fish | Well-cooked, flaked, bones checked twice |
| Shellfish | Well-cooked and finely chopped |
Cow's milk as a drink is a separate question from dairy as a food. Yogurt and cheese are ordinary first foods, while whole cow's milk as a beverage generally waits until after the first birthday.
Why did the advice change?
The reversal came from research showing that avoidance was not protecting children, and in some cases appeared to be doing the opposite. The pivotal work was the Learning Early About Peanut Allergy trial, which looked at infants at high risk of peanut allergy and found that regular early peanut consumption substantially reduced how many went on to develop it.
The AAP describes the shift plainly in its clinical report coverage, noting that peanut can be added for most babies as early as around 6 months, after other solid foods are tolerated. That is a full reversal of the guidance issued in 2000, which told high-risk families to avoid peanut until age three.
This matters practically because plenty of well-meaning advice still circulating in family groups is the old version. If a relative tells you to hold off on peanut until your baby is two, that advice was current once, and it is not current now.
How do you introduce an allergen safely?
Offer one allergen at a time, in a small amount, at a time of day when you will be awake and watching for the next few hours. Most families use late morning for exactly that reason.
Here is the sequence that current guidance supports.
- Pick a day when your baby is well. Skip it if they are sick, teething badly, or already having a rough day, because a fussy afternoon is harder to read.
- Offer a small taste, not a full serving. The AAP suggests portions on the order of two teaspoons of peanut or other nut butter, or roughly one third of a well-cooked egg.
- Wait and watch. Stay with your baby and keep them in view for the next couple of hours.
- If it goes well, keep that food in the rotation rather than treating it as done. Regular ongoing exposure is the part that matters, not the single first taste.
- Give it a day or more before adding the next new allergen, so that if something does happen you know which food to point at.
The AAP guidance on spacing new foods is to introduce one single-ingredient new food from any food group every 3 to 5 days and watch for reactions. Some families move faster once several allergens have gone smoothly. That is a reasonable thing to raise with your pediatrician rather than decide from a blog post.
How should peanut be served to a baby?
Never whole, and never as a thick spoonful of straight peanut butter. Whole peanuts are a choking hazard for children under four, and thick nut butter can be as well.
The AAP describes safe infant forms directly: mixing and thinning out a small amount of peanut butter in cereal, pureed fruit or yogurt, and notes that dissolving peanut butter in breast milk or formula and spooning it is another good option. Peanut puffs designed for infants are a third route many families use.
The same thinning principle applies to cashew butter, almond butter and tahini. Texture is the whole issue, so thin them until they stir in easily rather than sitting on the spoon in a lump.
Does the order you introduce them in matter?
No particular order is required, and no evidence points to one sequence being better than another. What matters is that all nine eventually get covered and then stay in the rotation afterward.
A practical order still helps, though, and most families end up working outward from whatever is easiest to serve at a texture a baby can manage.
- Dairy, as plain whole-milk yogurt, because it needs no preparation at all.
- Wheat, as the iron-fortified infant cereal you are probably already using.
- Egg, well cooked and mashed.
- Peanut, thinned as described above.
- Soy, as soft tofu, mashed.
- Sesame, as tahini stirred into a puree your baby already accepts.
- Tree nuts, as thinned cashew or almond butter.
- Fish, then shellfish, both well cooked and checked carefully for bones.
Pairing a new allergen with a food your baby already likes is a small trick that saves a lot of guessing. If sesame goes into a sweet potato puree that has been a reliable hit for two weeks, a refusal tells you something about the sesame rather than about the whole bowl.
Days off are worth using for this, not because a reaction is any more likely on a Saturday, but because the entire point is having unhurried hours to pay attention.
What does a reaction look like?
Most reactions in babies are mild and show up within minutes to a couple of hours. The AAP names rash, vomiting and diarrhea as the signs to watch for, and the instruction is to stop offering that food and check with your pediatrician.
A single skipped nap or one loose diaper is not usually an allergy signal on its own, which is exactly why writing down what you offered and when is so useful. It turns a vague worry into something you can actually answer.
What if your baby has severe eczema or an egg allergy?
This is the case where the guidance is different, and it is the one situation where you should not simply follow a general article.
Babies with severe persistent eczema or an existing immediate reaction to a food are considered higher risk. Current guidance points to peanut introduction earlier, in the four to six month window, but paired with medical involvement: the AAP notes that testing for peanut allergy and introduction under the supervision of a health care provider is a consideration for these infants.
If that describes your baby, the next step is a conversation with your pediatrician, not a first taste at your kitchen table. That is the whole recommendation, and it is worth following exactly.
How do you keep track of which allergens you have covered?
Once you are a few weeks in, the tracking problem gets real. You are holding the food, the date, whether anything happened, and which of the nine allergens are still outstanding, usually while quite tired.
A chart on the refrigerator beats an app for most families, because the person doing the feeding is already standing in the kitchen with both hands busy. Our Baby Food Introduction poster is built for this specific job: it is a laminated dry-erase allergen and food tracking chart, so you mark the date next to each allergen and wipe it clean for the next baby.
If you want the wider first-year picture alongside it, the 101 Foods Before 1 poster tracks variety across the whole year, and the Baby Feeding Poster Set (4 Pack) bundles both with a mealtime routine chart and a sign language chart for hunger and fullness cues. The rest of the range sits in baby feeding.
Once allergens are underway, the natural next step is variety, which is what the 100 Foods Before One challenge is built around. If you are still deciding how to serve food in the first place, the comparison in baby led weaning vs spoon feeding covers that choice, and either approach works with everything above.
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