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How do you introduce allergens to a baby? What the NHS says, and what we did

The NHS website says that when you start introducing solid foods from around 6 months, you introduce the foods that can trigger allergic reactions one at a time, so that you can spot any reaction.[1]

By Tom, a dad of two in Kent. Published 3 October 2026. NHS pages last checked 3 October 2026.

How this page works. Every health fact here comes from the NHS website and links to the page it came from, with that page's review date. The "In our house" box is our own experience. Nothing here is advice. For advice, go to the NHS page, your health visitor, or your GP.

Which foods the NHS lists

The NHS lists these foods as ones that can trigger an allergic reaction:[1]

  • eggs (the NHS says eggs without a red lion stamp should not be eaten raw or lightly cooked)[1]
  • nuts and peanuts (served finely ground or as nut butters)[1]
  • cows' milk[1]
  • foods that contain gluten, including wheat, barley, and rye[1]
  • beans, lentils, and peas[1]
  • seeds, particularly sesame seeds (served finely ground)[1]
  • soya[1]
  • shellfish (not served raw or lightly cooked)[1]
  • fish[1]
  • celery[1]
  • mustard[1]
  • sulphur dioxide, which is sometimes found in dried fruits and fruit juices[1]

One at a time, in small amounts

The NHS says these foods can be introduced from around 6 months, 1 at a time and in small amounts, so you can spot any reaction.[1][2]

It also says that once these foods have been introduced, and if they are tolerated, they should become part of a baby's usual diet to minimise the risk of allergy. It says evidence has shown that delaying the introduction of peanut and hens' eggs beyond 6 to 12 months may increase the risk of developing an allergy to them.[1]

Nuts

  • The NHS says you can give nuts from the time you start weaning, usually around 6 months, as long as they are crushed or ground and added to food.[3]
  • Nut butter, such as peanut butter, can be given from the start of weaning if it is spread onto a food such as toast. The NHS says not to give nut butter on its own, because a child could choke.[3]
  • Whole nuts should not be given to children under 5 years old, because they can choke on them.[3]
  • If there is a history of food allergies or other allergies in your family, the NHS says to talk to your GP or health visitor before introducing any type of nut.[3]

If your baby may be at higher risk

If a baby already has an allergy, such as a diagnosed food allergy or eczema, or there is a family history of food allergies, eczema, asthma, or hay fever, the NHS says you may need to be particularly careful when introducing foods, and to talk to your GP or health visitor first.[1]

What an allergic reaction can look like

The NHS says allergic reactions usually happen within a few minutes of a baby trying a new food, but it may take up to 2 hours for symptoms to appear. In some allergies, such as cows' milk allergy, it can take up to 3 days.[1]

The NHS lists these possible signs:[1]

  • swollen lips or face[1]
  • red, itchy, watery eyes[1]
  • wheezing and coughing[1]
  • a red, itchy rash[1]
  • worsening of eczema symptoms[1]
  • feeling or being sick[1]
  • tummy pain, diarrhoea, or constipation[1]

The NHS says most allergic reactions are mild, but occasionally a severe reaction called anaphylaxis can occur. It says anaphylaxis is a medical emergency and needs urgent treatment.[1]

Cutting out foods

The NHS says not to be tempted to experiment by cutting out a major food, such as milk, because this could lead to a child not getting the nutrients they need. It says to talk to your health visitor or GP, who may refer you to a registered dietitian.[1]

In our house

We followed the NHS guidelines and introduced allergens one at a time. Our children had no reaction to any of them. Once a food had gone well, we offered it more often and in bigger amounts. We were careful with nuts and honey. This is what we did, not a recommendation.

If you are worried

This page is a summary of NHS information plus our own experience. It is not medical advice. If you think your baby may be having an allergic reaction, the NHS has a page on anaphylaxis. You can also speak to your health visitor or GP, or use NHS 111.

Sources

  1. NHS website: Food allergies in babies and young children. Page last reviewed 22 October 2024; next review due 22 October 2027; page last updated by the NHS on 20 March 2026. I checked it on 3 October 2026.
  2. NHS website: Your baby's first solid foods. Page last reviewed 19 February 2026; next review due 19 February 2029; page last updated by the NHS on 10 March 2026. I checked it on 3 October 2026.
  3. NHS website: Foods to avoid giving babies and young children. Page last reviewed 18 February 2026; next review due 18 February 2029; page last updated by the NHS on 29 September 2026. I checked it on 3 October 2026.

Contains public sector information licensed under the Open Government Licence v3.0. This page summarises NHS website content in our own words, and an adaptation may not carry the NHS's formal clinical approval. Tiny Tummies is not affiliated with or endorsed by the NHS.

About the author

I am Tom, a dad of two in Kent. When I wrote this, our children were 3 years 9 months and 16 months old. I am not a clinician, and nothing here is medical advice. I also built Tiny Tummies, a baby feeding tracker. I use AI tools to help draft these pages. Every health fact is checked against the NHS page it links to, and the "In our house" boxes are what my wife and I actually did.