When to Introduce Food Allergens to Your Baby: A Parent's Guide
Your baby's first tastes of solid food are a lovely milestone. For many parents they're also a slightly nerve-racking one, especially when it comes to foods like peanut and egg. If you've heard conflicting advice, you're not alone.
The good news is that the evidence is now clear. Offering these foods early, then keeping them in your baby's diet, is one of the most effective things you can do to lower their risk of food allergy. This guide walks you through when to start, what the first taste looks like, how much to offer and what to do if something doesn't seem right.
In a nutshell
- Start from three-four months, once your baby is ready for solids. Begin with pureed fruit and vegetables, then egg and peanut. This applies to all babies, not only those at higher risk of allergy.
- Once a food suits your baby, keep giving it to them regularly. Aim for around two level teaspoons of smooth peanut butter and at least one egg across each week, divided across about three meals.
- Consistency and quantity matter. Keep these foods in your child's diet regularly and in the recommended amounts, through their first five years.
- Early introduction should take place alongside breastfeeding.
- Ensure that you give the food to your child in a suitable form. For example, never give whole or chopped nuts to a young child, to avoid choking. Instead use smooth nut butter or finely ground nuts, made into an appropriate consistency, for example with breast milk.
Why starting early helps
For years, parents were told to keep babies away from foods like peanut. Our research challenged that advice and found that early introduction protected babies from developing food allergies. Ideally common food allergens, especially egg and peanut should be introduced by four months of age in high risk babies, and at 4-6 months of age in lower risk babies.
It all began with a puzzle. Professor Gideon Lack and his colleagues noticed that peanut allergy was far less common among children in Israel, where babies often eat peanut snacks from an early age, than among British children of a similar background, whose parents usually avoided peanut. Could the timing of that first taste make the difference?
The LEAP study set out to answer that question. It followed 640 babies at high risk of peanut allergy. Those who ate peanut regularly from infancy were 86% less likely to have peanut allergy at age five than those who avoided it. The earlier peanut was introduced in the first year of life, the more effective it was at preventing peanut allergy in all children, but especially in the infants with the most severe eczema. When we followed the same children into their teenage years, the protection had lasted; at 12 years of age, peanut allergy remained less common in those who ate peanut early, even though they'd eaten as much or as little peanut as they liked from age six.
Our EAT study then looked at six common allergens in 1,303 breastfed babies from the general population. Among families who managed to follow the early-introduction plan, food allergy was around two thirds less common. Importantly, this benefit was seen in both babies with and without eczema.
The results are now showing up in whole populations. After the US changed its guidance in 2017, advocating early peanut introduction in all babies, peanut allergy in young children fell by around 43%.
Why does timing matter so much? The leading explanation is that when a baby first meets a food by eating it, their immune system learns to treat it as safe. However when a baby has eczema, those first encounters can happen when foods, which are universally present in the environment, make contact with the baby’s dry, inflamed eczematous skin. Exposure though the skin is more likely to lead the immune system to develop an allergy to the food. Allergies to egg and peanut can also develop when babies are just a few months old, which is why starting food allergen introduction early in life is important. Furthermore, the more severe the eczema is, the earlier this window of opportunity is likely to close.
"By six to eight months of age, a significant proportion of children who will develop peanut allergy have already developed it, and we will have missed the boat for those children." – Professor Gideon Lack
What about the evidence for other allergens?
The evidence is strongest for peanut and egg, which have been studied in several large, well-designed trials. There is also evidence that early introduction of dairy into the baby’s diet can prevent cows milk allergy. For many other allergens, such as tree nuts, sesame, wheat and fish, there are fewer studies looking specifically at whether early introduction prevents allergy. This is partly because, once early introduction was shown to be beneficial, it became increasingly difficult to justify asking families to delay these foods simply to test whether early introduction was also beneficial for other allergens.
The lack of the same level of evidence does not mean these foods should be delayed. Current guidance recommends introducing other common allergens once your baby is ready for solid foods, and continuing to include them regularly once introduced.
Is your baby ready?
Your baby's development is a better guide than the calendar. Look for signs that your baby is ready for solids. Can they attempt a sitting position and they are starting to display an interest in food? If your baby is persistently refusing to swallow and pushing the food out with its tongue, they may not be ready. If they have feeding difficulties, seek advice from your healthcare specialist.
Once your baby is managing simple first foods such as puréed vegetables and fruit, you can bring in egg and peanut, then the other allergens that your family eats.
Babies who may benefit from advice
If you are concerned about your baby reacting to foods, for example they have already developed a food allergy, have severe eczema (that would need daily steroid creams to control), or their elder sibling has a food allergy, they may benefit from reassurance before their first taste of egg or peanut. These babies are more likely to have already developed a food allergy, so a careful plan helps make their first introduction safe.
The aim is never to delay food introduction. Babies with eczema often have the most to gain from early introduction, so the sooner a plan is in place, the better. Good eczema care matters too. Our guide to baby eczema and food allergy explains more, as does our guide to the signs a baby may be at higher risk.
If your baby has already reacted to a food, or has a diagnosed allergy to it, don't offer that food again without medical advice.
Your baby’s first allergen day
Most babies eat egg, peanut and other allergens without any problem, and a little preparation will help you feel calm and confident. Firstly, make sure your baby is already consuming pureed fruit or vegetables
- Pick a good day. Choose a morning when your baby is well and you can stay at home without other commitments. This gives you time to introduce the food calmly and observe your baby afterwards. If they're unwell, any new symptoms are harder to read
- Introduce one new allergen at a time. That way if your baby does react, you'll know which food caused it. You can introduce a new allergen every day. Contrary to popular belief, you do not need to wait 3 days between introducing new foods
- Start with a small taste. Mix a little of the food into something your baby already enjoys. The table below gives ideas for each allergen. If all is well, offer the food again, increasing the amount. Then make it a regular part of their meals.
- Stay close. Keep your baby upright or supported and stay with them while they eat.
- Keep an eye on your baby afterwards. Most allergic reactions happen within minutes, but they can occasionally take up to two hours. Make sure you have time to stay with your baby and watch for any symptoms after introducing the food.
- Offer the food in an age-appropriate way. Whole nuts, pieces of nuts and thick nut butter can pose a choking risk. Finely grind whole nuts, or if using a nut butter to introduce an allergen, thin it well with water, breast milk, formula or purée.
Keeping it going
Introduce common food allergens early. Then keep an appropriate portion in the diet regularly. Aim for about two level teaspoons of smooth peanut butter and at least one egg a week, spread over around three meals, and continue to give this through the first five years. In the LEAP trial, regular peanut consumption from infancy cut peanut allergy at age five by 86% in infants at high risk, and follow-up found that protection was maintained into adolescence.
This is the part that makes the difference, and it's also the part parents find hardest. In our EAT study, parents introduced six foods into their babies’ diets. Only around 40% of families managed the full plan, because giving several allergens several times a week to a very young baby isn't easy. So try to keep the foods in your baby’s diet as part of your routine, aiming for regular exposure as much as possible. Missing an occasional dose is not a reason to give up.
Another important aspect is the amount of the food to give. A useful guide is around two grams of allergen protein per week for each food, as the protective effect appears to weaken as intake falls. In practice, that means:
- Peanut: around two level teaspoons of smooth peanut butter across the week
- Egg: at least one egg across the week
Spread each amount over about three meals rather than offering it all at once. Keep these foods in your child's diet regularly, at least through their first five years.
A few things that help busy families:
- Stir allergens into foods your baby already loves. Breast milk, porridge, yoghurt and fruit purée all work well.
- Make a batch and freeze it. Cook a batch of egg-based fingers or peanut porridge, then freeze it in small portions.
- Plan allergens into your week. Linking them to particular days, such as "peanut Mondays", makes them easier to remember.
You can carry on breastfeeding throughout. In the EAT study, early introduction didn't shorten how long mothers breastfed.
The main allergens, one by one
Start with egg and peanut, which have the strongest evidence behind them. Then introduce other allergens one at a time as part of the foods your family eats. Start with a small amount as their ‘first taste’. Build up to a regular amount, aiming for at least 1 teaspoon of an allergen per sitting, incorporated weekly into their diet. Mix the food with something they are familiar with and enjoy, such as expressed breast milk, until the texture is smooth and easy to swallow.
If cow's milk seems to cause symptoms hours or days later, our guide to cow's milk protein allergy explains what to look for.
Once your baby has tried each food on its own and it suits them, allergens can simply become part of everyday meals. Start by introducing the common foods over one whole month, until a feeding pattern is well established. Then sequentially introduce other tree nuts: cashew, walnut, almond, macadamia, pine nut, brazil nut, hazelnut. Cashew and pistachio nuts provide mutual protection, as do walnut and pecan. Therefore introducing cashew and walnut can provide protection against cashew, pistachio, walnut and pecan allergies.
If your baby refuses
Turning away from an unfamiliar food or texture is a normal part of learning to eat. It doesn't mean your baby is allergic. However if they display a recurrent aversion to a food, then suspect the possibility of an allergy.
Introducing new foods should be a positive experience. If your baby isn't keen, take a break for a few days, then try again in a different form. You can make allergenic foods easier to accept by mixing them into foods your baby already enjoys, such as smooth nut butter in breast milk, porridge or yoghurt, whole cooked egg blended with water or breast milk into a custard-like texture, or peanut puffs softened with breast milk or purée.
Spotting an allergic reaction
Most reactions in babies are mild, but it's important to know which signs need urgent help.
Signs of a mild to moderate reaction usually appear within minutes and up to two hours after eating. They include hives, swelling of the lips, face or eyes, vomiting, and tummy pain. If you see these, stop offering the food and contact your GP or NHS 111.
Some signs of a serious reaction (anaphylaxis) include:
- a swollen tongue
- a persistent cough or hoarse cry
- difficult or noisy breathing
- a baby becoming blue, pale, floppy or unusually unresponsive
If you notice any of these, call 999 immediately and say you think your baby is having anaphylaxis.
Other reactions take hours or days to appear. Look out for repeated vomiting, worsening reflux, persistent changes in their poo, refusing food or worsening eczema. Speak to your GP if these continue or come back when your baby eats a particular food. Don't avoid major foods for long periods without advice.
Don't offer a food you suspect your child has reacted to again, and discuss this with a healthcare professional. If your child already has a diagnosed food allergy, our guide to food oral immunotherapy may help.
How the evidence differs from current NHS guidance
The NHS currently advises most families to start solids, including allergens, at around six months.
Based on the evidence from the most current research, allergens should be introduced as early as three-four months old, for all babies who are developmentally ready. UK allergy and dietary specialist guidance, from the British Society of Allergy and Clinical Immunology (BSACI) and British Dietetic Association (BDA), is aligned with this. They recommend the earlier introduction of egg and peanut from four months for babies at higher risk. Other countries have moved in a similar direction. European guidance suggests four to six months of age for introducing egg and peanut, and the US updated its peanut guidance in 2021 to recommend that peanut, egg, and other major allergenic foods were introduced to ALL infants, whether or not they were at a high risk of developing food allergies, around 4-6 months of age.
In June 2026, Professor Lack and 14 leading allergy clinicians, researchers and patient advocates called for NHS guidance to be updated in an open letter published in The Sunday Times.
"The question is no longer whether early introduction works, but whether we are doing enough to implement what we already know." – Professor Gideon Lack
You can read more about the evidence on our allergy prevention page.
What doesn't help
- Avoiding allergens during pregnancy or breastfeeding hasn't been shown to prevent food allergy in your baby.
- Special formulas marketed as "low allergy" aren't recommended purely for allergy prevention.
- Probiotics don't yet have enough evidence behind them to recommend specifically for preventing food allergy.
What does help is early introduction, maintained regularly, and keeping your baby's eczema well controlled. Follow NHS advice on vitamin D, which depends on how your baby is fed.
Frequently asked questions
Is three-four months too early to give my baby peanut or egg?
Not if your baby is developmentally ready for solids. We recommend introducing egg and peanut from three-four months once your baby shows the signs of readiness, and has started to have pureed fruit or vegetables. NHS advice for most babies is currently to start solids at around six months. If your baby has severe eczema, another food allergy, or a brother or sister with a food allergy, you may wish to get individual advice first.
How much peanut or egg does my baby need?
Once your baby has tolerated the food, aim for around two level teaspoons of smooth peanut butter and at least one egg across the week. Spread these portions over about three meals, and keep them going regularly through your child's first five years.
My baby has eczema. Should I wait?
No. Babies with eczema often have the most to gain from early introduction. If the eczema is severe, speak to a specialist or your GP first, so the first taste can be planned safely and without unnecessary delay. The earlier your baby starts having food allergens in their diet, the more likely they are to be protected against food allergies
What if my baby has a reaction?
Most reactions are mild. Stop offering the food and contact your GP or NHS 111. If you see signs of anaphylaxis, such as difficulty breathing or your baby becoming floppy, call 999 straight away.
Concerned your child is affected by allergies?
