Introducing Allergens to Your Baby: When Can They Have Peanut Butter?

If you have older relatives, they may remember being told to keep peanuts and eggs away from babies for as long as possible. That advice has changed. Current UK guidance now supports introducing common food allergens from around six months, as part of normal weaning, rather than holding them back.

The shift came from research suggesting that delaying allergens doesn't prevent allergies — and may even make them more likely. Influential studies, often referred to by names like LEAP (Learning Early About Peanut Allergy) and EAT (Enquiring About Tolerance), explored introducing allergenic foods earlier in infancy. Broadly and qualitatively, this body of work pointed towards early, regular exposure being associated with a lower chance of developing certain food allergies, rather than a higher one — reversing the old "avoid" thinking.

We won't put numbers on those studies here, because the safe, honest summary is directional: early introduction is now encouraged, not feared. The common allergens to include deliberately during weaning are cow's milk (in cooking), eggs, foods containing gluten (like wheat), nuts and peanuts (as smooth butters or ground), seeds, soya, shellfish and fish.

This is feeding support, not medical advice. If your baby is at higher risk of allergy, or you have any concerns, please speak to your GP or health visitor before introducing allergens — more on that below.

The golden rule when introducing any allergen is: one new allergen at a time, and not all at once. This isn't about being cautious for the sake of it — it's about being able to identify the culprit if a reaction does happen.

Here's how it works in practice:

• Introduce one allergen on its own, in a small amount, when your baby is well (not unwell, teething badly or already unsettled).
• Offer it earlier in the day, ideally at home, so you can watch your baby over the following hours rather than introducing it right before bed.
• Wait a few days before introducing the next new allergen. Leaving a gap means that if a reaction appears, you'll know which food caused it rather than guessing between several.
• If all is well, keep that allergen in the diet (more on this below) and move on to the next one.

You don't need to rush through the list, and you don't need to avoid the rest of your baby's meals while you do it — you're simply layering in one new allergen at a time against the backdrop of their usual foods.

The right format matters as much as the timing — partly for allergy introduction and partly for choking safety. Remember: whole nuts are a choking hazard and must not be given under five years. The allergen is introduced through safe, smooth or well-cooked forms instead.

Allergen	Safe format for a baby
Peanut	Smooth peanut butter thinned with your baby's usual milk or water into a loose paste, or a little ground/powdered peanut stirred into food. Never whole or chopped nuts, and never thick, sticky spoonfuls of stiff peanut butter.
Egg	Well-cooked egg — cooked until both white and yolk are solid (for example, hard-boiled and mashed, or thoroughly cooked into food). Avoid raw or runny egg.
Cow's milk	Used in cooking and in dairy foods like yoghurt and cheese from six months. Cow's milk shouldn't be the main drink until 12 months.
Other nuts	Smooth nut butters (thinned) or finely ground nuts — never whole or chopped.
Fish and shellfish	Thoroughly cooked, with all bones and shell removed.

The thinning point for peanut butter is worth stressing: a thick smear of stiff peanut butter is both a choking risk and hard for a baby to manage. Loosening it into a thin paste with milk or water solves both problems. The same food-safety rules from the rest of weaning still apply — no honey before 12 months, no added salt or sugar, always upright and supervised. Because whole nuts are a choking hazard, our guide to choking vs gagging is worth reading alongside this one.

For most babies, allergens can be introduced confidently at home from around six months. But some babies are at higher risk of food allergy, and for them the advice is different: talk to your GP or health visitor before you begin.

A baby may be higher risk if they have:

• Moderate or severe eczema, particularly if it started early or is hard to control
• An existing diagnosed food allergy (for example, a known egg allergy when you're about to introduce peanut)

Higher risk doesn't mean you should avoid allergens — that's the old thinking, and it isn't the answer. In fact, early introduction may be especially important for these babies. But it should happen with professional guidance, so that the timing, the setting and any precautions are right for your individual child. Your GP can advise, and in some cases may involve an allergy specialist.

If you're at all unsure whether your baby falls into a higher-risk group, treat that uncertainty as a reason to ask. A quick conversation with your GP or health visitor before you start is exactly what this guidance is for.

Most reactions, when they happen, are mild. Knowing the signs means you can respond calmly and appropriately. Mild reaction signs can include:

• Redness, hives or an itchy rash — often around the mouth or where food touched the skin
• Mild swelling of the lips or face
• An itchy or tingly mouth
• A runny or blocked nose, sneezing, or watery eyes
• Tummy upset — vomiting or loose stools

Mild reactions should be discussed with your GP, who can advise on next steps and whether that food should be paused. But you also need to know the signs of a severe allergic reaction (anaphylaxis), which is a medical emergency.

Call 999 immediately if your baby has any of these signs:

• Swelling of the tongue, throat, lips or mouth
• Difficulty breathing — noisy breathing, wheezing, a persistent cough, or struggling to breathe
• Becoming pale, floppy, unresponsive or losing consciousness

Say clearly on the phone that you think your baby is having an anaphylactic reaction. Anaphylaxis is rare, but it is why introducing allergens one at a time, earlier in the day, at home, while your baby is well, matters so much — it puts you in the best position to notice and act. This blog cannot diagnose or treat an allergy; its job is to help you recognise when to seek help fast.

Here's the step that's easy to forget: introducing an allergen once isn't the finish line. Once your baby has tolerated an allergen, the current advice is to keep it in their diet regularly — roughly a few times a week — rather than trying it once and then dropping it for months.

The thinking is that regular, ongoing exposure helps maintain tolerance. Reintroducing a food after a long gap isn't quite the same as never stopping in the first place. So once peanut, egg and the others are safely part of your baby's diet, weave them back in as normal foods — a little peanut butter on toast fingers, egg in cooking, yoghurt as a regular option.

This is genuinely reassuring: it means allergen introduction folds into ordinary family eating rather than being a scary one-off test. Our Starting Solids course (£67) includes a practical plan for working through the allergens calmly, and our when to start weaning guide helps you make sure your baby is genuinely ready before you begin.

This is feeding support, not medical advice. For higher-risk babies, any reaction, or if you're ever unsure, please speak to your GP or health visitor — and call 999 for the anaphylaxis signs above.

Introducing allergens can feel like the most nerve-racking part of weaning, but the modern approach is clear and manageable. UK guidance now supports early introduction from around six months, because delaying allergens doesn't prevent allergies and may make them more likely.

Introduce one allergen at a time, in safe formats — thinned smooth peanut butter, well-cooked egg, never whole nuts. If your baby has moderate-to-severe eczema or an existing food allergy, speak to your GP first. Watch for reactions, know the 999 anaphylaxis red flags — swollen tongue or lips, breathing difficulty, floppy or unresponsive — and once an allergen is tolerated, keep it in the diet regularly.

Done this way, allergen introduction becomes a confident, ordinary part of feeding your baby rather than a source of dread.