Allergies, Intolerances and Anaphylaxis

An allergen is a substance that can set off an allergic reaction. In an allergy, the immune system treats an allergen as a threat, even though it is harmless to most people. The body releases chemicals that cause symptoms in the skin, nose, eyes, airways or digestive system.

Allergies can begin in childhood or start later in life. Some fade over time, while others continue. The strength of a reaction can also change between one occasion and the next, which is why a previously mild allergy should still be taken seriously.

• Foods — including milk, eggs, peanuts, tree nuts, fish, shellfish and others.
• Pollen — from grasses, trees and weeds (hay fever).
• House-dust mites — found in bedding, carpets and soft furnishings.
• Mould — including damp indoor mould and outdoor mould spores.
• Animals — usually skin flakes, saliva or urine rather than the fur itself.
• Insect stings — such as wasp and bee stings.
• Medicines — including some antibiotics and anti-inflammatory painkillers.
• Latex — such as some gloves, balloons and rubber products.
• Skin products, cosmetics and hair dye — including fragrances and preservatives.

Almost any substance can cause a reaction in someone, and triggers differ from person to person. What affects one person may have no effect at all on another.

Mild and moderate symptoms can include:

• sneezing, or a blocked or runny nose
• itchy, red or watery eyes
• coughing
• wheezing
• itchy skin
• hives or a raised rash
• swelling
• stomach cramps
• nausea, vomiting or diarrhoea

Symptoms may begin within minutes of contact with an allergen, or they may take several hours to appear.

Redness and rashes can be harder to see on brown or black skin. Changes in skin texture, swelling, itching and how the person says they feel are just as important as any visible colour change.

• An allergy involves the immune system and can sometimes cause anaphylaxis.
• A food intolerance usually causes digestive symptoms such as bloating, wind or stomach discomfort, and does not cause anaphylaxis.
• Coeliac disease is an autoimmune condition triggered by gluten. It is not the same as a food allergy or a simple intolerance, and it needs proper medical assessment.

Please do not remove major foods from your own diet, or a child’s diet, without medical or dietetic advice. Cutting out foods can cause nutritional problems and can also delay or prevent a proper diagnosis, because some tests need the food to still be part of the diet.

Common food triggers include milk, eggs, peanuts, tree nuts, fish, shellfish, wheat, soya and sesame.

Practical steps that many people find useful:

• Check ingredients every time, because recipes and manufacturing can change.
• Avoid a food when the ingredients are uncertain.
• Tell restaurants, cafés, schools, nurseries, carers and workplaces about the allergy.
• Prevent cross-contact through utensils, chopping boards, surfaces and shared cooking equipment.
• Keep prescribed emergency medicines available and in date.
• Ask for professional advice before making significant changes to a diet.

UK food businesses must declare these 14 allergens when they are used as ingredients:

• celery
• cereals containing gluten, including wheat, rye, barley and oats
• crustaceans
• eggs
• fish
• lupin
• milk
• molluscs
• mustard
• tree nuts
• peanuts
• sesame
• soya
• sulphur dioxide and sulphites above the regulated level

Peanuts and tree nuts are separate allergen categories. Someone may react to one and not the other, so both need to be checked.

• Allergens in prepacked food must be emphasised in the ingredients list, for example in bold type.
• “May contain” warnings relate to a possible cross-contact risk during preparation or manufacturing.
• “Free from” is a specific safety claim about that product.
• Vegan labelling does not automatically mean a product is safe for someone with a milk, egg or other food allergy, because it describes the recipe rather than the cross-contact risk.
• Food that is prepared and packaged on the same premises before it is sold must carry a full ingredients list with allergens emphasised.
• Recheck familiar products, because ingredients and manufacturing processes can change without any obvious difference to the packaging.

Tell staff clearly about the allergy, ask whether the meal and the way it is cooked are suitable, and check again when the food arrives.

Takeaway businesses must make allergen information available before a purchase is made and again when the food is delivered. If you are ordering for several people, ask for the separate containers to be clearly identified so the right meal reaches the right person.

No restaurant can be assumed to guarantee complete safety. Only the business itself can confirm whether it is able to meet a particular person’s needs, so it is reasonable to ask directly and to choose somewhere else if you are not confident in the answer.

Pollen, house-dust mites, mould and animals are common triggers. Practical steps include:

• checking pollen forecasts
• keeping windows closed when pollen levels are high
• showering and changing clothes after being outdoors
• using a damp cloth for dusting rather than a dry one
• vacuuming regularly
• avoiding known triggers where that is reasonably possible
• asking a pharmacist about suitable antihistamines, eye drops or nasal treatments

Some antihistamines can cause drowsiness. Follow the patient information leaflet and the pharmacist’s advice, and take particular care before driving or using machinery.

Contact dermatitis is a skin reaction to something that has touched the skin. Common causes include cosmetics, fragrances, metals such as nickel, latex and hair dye. The skin may become itchy, dry, sore, cracked or blistered.

If you think a product is causing a reaction, stop using it, keep the packaging or ingredient information, and ask a pharmacist or GP for advice.

Call 999 if there is swelling of the mouth or throat, or any difficulty breathing.

Home allergy tests and do-it-yourself skin-testing methods are not recommended. Ask a healthcare professional instead.

• a written allergy-management plan agreed with the healthcare team
• informing all relevant staff, not only one person
• keeping prescribed medicines accessible rather than locked away
• checking expiry dates regularly
• making sure responsible adults know exactly what to do
• planning ahead for trips, clubs, parties and school meals
• teaching children age-appropriate ways to explain their allergy and ask for help

A child should not be expected to manage a serious allergy alone. Adults around them share that responsibility.

Contact a GP if you think you or your child may have an allergy. Assessment may include:

• a detailed history of symptoms and possible triggers
• a food-and-symptom diary
• skin-prick testing
• blood testing
• a medically supervised food challenge
• referral to an allergy clinic or a dietitian

Commercially sold home allergy or intolerance tests may be unreliable and should not replace NHS or other medically supervised assessment.

• avoiding confirmed triggers where possible
• antihistamines
• nasal sprays, eye drops or prescribed creams
• a written allergy-management plan
• adrenaline auto-injectors for people at risk of severe reactions
• carrying two prescribed auto-injectors if that is the advice given
• checking expiry dates and replacing devices in good time
• knowing how to use the specific device that has been prescribed
• making family, friends, carers, schools and workplaces aware
• wearing medical identification if that feels helpful
• immunotherapy or desensitisation, only under specialist medical supervision

Do not start, stop or change any medication without professional guidance.

It helps to know the difference between a known allergy that has been confirmed, a suspected allergy that has not yet been assessed, and a side effect, which is an unwanted effect of a medicine that does not involve an allergic reaction.

Tell doctors, dentists and pharmacists about any previous reaction to a medicine, and what happened, so it can be recorded.

Do not stop essential prescribed medicine suddenly. If a medicine appears to be causing a reaction, seek prompt professional guidance — and call 999 for severe symptoms such as swelling of the throat or difficulty breathing.

• take enough prescribed medication for the whole trip, with some to spare
• keep emergency medicine accessible in hand luggage rather than in checked luggage
• carry a copy of the management plan or the prescription
• check airline and accommodation arrangements before travelling
• learn how to explain the allergy in the language of the destination
• check travel-insurance terms, including cover for existing conditions
• check food ingredients rather than relying only on how a dish looks

Explaining an allergy can be harder for someone who has dyslexia, anxiety, a disability or communication difficulties. These practical steps can help:

• keep a written list of confirmed allergies
• use an allergy card or a note saved on a phone
• take someone trusted to appointments
• ask for information in writing
• request reasonable communication support
• keep photographs of medicine labels and management plans where that is appropriate

If you would like help writing to a GP surgery, school, food business or other service about allergy-related needs or concerns, our Free Letter and Complaint Support page explains how we may be able to help with the wording.

Emergency — call 999 for suspected anaphylaxis, or for serious breathing or swelling symptoms.

Urgent advice — use NHS 111 when urgent medical help is needed but the situation is not immediately life-threatening.

Routine advice — speak to a pharmacist or GP about suspected allergies, persistent symptoms, testing, treatment or concerns about a medicine.

Health services are arranged differently across the United Kingdom. Use the link for the nation you live in:

These are official or well-established UK sources. Details can change, so please check the information on the organisation’s own website.