An overview of the 14 most common allergens

What are allergens?

Allergens are naturally occurring or artificially produced substances that the immune system recognises as foreign and attacks. In the case of food allergies in particular, allergens are those components in food that are normally tolerated without any problems by healthy people. In people with allergies, however, these substances can trigger allergic reactions.

What are food allergies?

In the case of a food allergy, the immune system of the person affected reacts to a substance that is in itself harmless – such as a component of food (allergen) – with an excessive immune response. In this process, the body produces so-called IgE antibodies, and symptoms occur very quickly upon renewed contact with the allergen. These range from itching, swelling and a burning sensation in the mouth to more severe reactions such as shortness of breath, asthma or even anaphylactic shock.

It is important to distinguish between food allergies and food intolerances (also known as pseudo-allergies). In the case of an intolerance, there is no immune response from the body, but the body is unable to break down or absorb certain components of food, such as histamine or fructose. Food intolerances, such as lactose intolerance, are significantly more common than true food allergies.

Furthermore, people with allergies may suffer from cross-reactivity, whereby the immune system reacts not only to a specific allergen but also to similar substances. An example of this is an excessive immune response to both certain types of pollen and allergens in plant-based foods.

What are the 14 most common food allergens?

There are 14 major food allergens that must be labelled within the EU – this applies to packaged foods as well as loose goods and dishes served in restaurants, for example.

What is gluten?

Gluten, often referred to as wheat gluten, is a mixture of proteins found in cereals such as wheat, rye, oats, barley and spelt. It is also found in numerous processed products such as flour, baked goods, meat and sausage products, sweets and many ready meals. Gluten can cause health problems in some people. Experts distinguish between the following:

• Coeliac disease (gluten intolerance): This is an autoimmune disorder, not an allergy. It leads to changes in the small intestine and requires a lifelong, strictly gluten-free diet.
• Non-coeliac sensitivity to gluten or wheat: In this case, symptoms – particularly in the gastrointestinal tract – occur without any changes to the small intestine.
• Immediate-type wheat allergy: In this case, those affected have an allergic reaction to the gluten in wheat or other wheat components.

What are the symptoms of a wheat allergy?

A wheat allergy can cause various symptoms:

• Skin reactions: The most common symptoms affect the skin, often manifesting as redness, itching and hives (urticaria).
• Respiratory difficulties: Those affected may suffer from breathing difficulties and asthma.
• Mouth and throat: Swelling in the mouth and throat may occur.
• Cardiovascular system: A sensation of warmth or heat may occur, sometimes leading to anaphylactic shock, a severe and potentially life-threatening reaction.

What treatment is available for a wheat allergy?

Once a clear diagnosis has been made, the treatment for a wheat allergy involves avoiding wheat and similar cereals, such as spelt, green spelt and kamut. This also includes all products containing these cereals. People at high risk of severe anaphylactic reactions should also always carry an emergency kit with them.

2. Allergen B: Shellfish

Which shellfish can trigger allergic reactions?

Crustaceans that can trigger allergic reactions include, in particular, crayfish, lobsters, spiny lobsters, prawns, shrimps and crabs.

What are the symptoms of an allergic reaction?

The symptoms of an allergy to crustaceans can vary widely.

These include, amongst others:

• Gastrointestinal problems
• Swelling of the mucous membranes

In the worst-case scenario, this can lead to life-threatening anaphylactic reactions.

What treatment is available for a shellfish allergy?

The most effective treatment for a shellfish allergy is to consistently avoid the foods in question. Individual symptoms can be treated symptomatically with drops, sprays, creams, ointments and, if necessary, antihistamines or cortisone. In the event of severe anaphylactic reactions, emergency management must be initiated (emergency kit).

3. Allergen C: Eggs

Why do eggs frequently trigger a food allergy?

Eggs, a common ingredient in many processed foods such as baked goods, ready meals, breaded foods, pasta, sauces or salads, can cause allergic reactions. An egg allergy involves an allergic reaction to certain protein components in poultry eggs.

What are the symptoms of an allergic reaction?

The symptoms of an egg allergy can vary widely.

Common symptoms include:

• Itching in the mouth and on the skin
• Redness, swelling and hives on the skin
• Respiratory problems
• Gastrointestinal symptoms (rare)

In very rare cases, anaphylactic shock may also occur.

What treatment is available for an egg allergy?

The key treatment strategy for an egg allergy is to avoid eggs and products containing eggs. The strictness of this avoidance depends on the individual’s sensitivity and the severity of the allergy.

4. Allergen D: Fish

What are the main allergens in fish?

The allergens in fish are mainly so-called parvalbumins. These are proteins that cannot be destroyed even by cooking.

Which types of fish most commonly trigger allergies?

Herring, sardines, cod, hake, pollock, swordfish, tuna, mackerel, salmon, trout, char, carp, redfish, halibut, sole, pangasius and eel can trigger a fish allergy.

What are the symptoms of a fish allergy?

The following symptoms may occur with a fish allergy:

• Tingling, burning and swelling in the mouth and throat
• Gastrointestinal symptoms such as abdominal pain, vomiting or diarrhoea
• Skin symptoms such as itching, redness or hives
• Respiratory symptoms, e.g. allergic rhinitis, asthma

In the worst-case scenario, anaphylactic shock may also occur.

What treatment is available for a fish allergy?

The key measure is to avoid eating the types of fish to which you are allergic. People at risk of anaphylactic shock should always keep an emergency kit to hand.

Allergen E: Peanuts

What triggers a peanut allergy?

Peanut allergies are triggered by proteins in peanuts, which can cause allergic reactions even when roasted or cooked.

Why is a peanut allergy so dangerous?

Peanut allergies are particularly likely to result in severe allergic reactions such as anaphylactic shock.

What cross-allergies can occur?

Cross-allergies can occur, particularly with birch pollen and grass pollen.

What are the symptoms of a peanut allergy?

Possible symptoms include:

• Tingling, burning and swelling in the mouth and throat
• Stomach ache
• Vomiting
• Diarrhoea
• Allergic rhinitis
• Asthmatic symptoms
• Skin symptoms such as redness, itching and hives
• Eczema flare-ups

Severe allergic reactions can lead to anaphylactic shock, with breathing difficulties and circulatory failure.

What treatment is available for a peanut allergy?

The main strategy is to avoid peanuts. It is also important to be aware of hidden sources in baked goods, sausages, spice mixes, and semi-prepared and ready-made products. People at high risk of anaphylactic shock should always carry an emergency kit with them. There are also approaches to desensitisation.

6 Allergen F: Soya beans

What is the trigger?

The trigger for a soya allergy is soya protein.

The following foods, amongst others, can trigger a soya allergy:

• Soya drinks
• Tofu
• Soya flakes
• Soya flour
• Soya products such as soya pudding or soya yoghurt

What are the symptoms of a soya allergy?

Possible symptoms include:

• Tingling, a burning sensation and swelling in the mouth and throat
• Gastrointestinal symptoms such as abdominal pain, vomiting or diarrhoea
• Skin reactions such as redness or itching
• Allergic rhinitis, coughing or asthmatic symptoms

In some cases, severe allergic reactions may also occur, leading to anaphylactic shock.

What treatment is used?

The only possible measure is to avoid the trigger. People at high risk of anaphylactic shock need an emergency kit.

7 Allergen G: Milk

What are the triggers?

In the case of a milk allergy, the body reacts to certain proteins contained in milk. Milk allergies mainly affect babies and children under the age of 5 and often resolve themselves before the child starts school.

What are the symptoms of a milk allergy?

The symptoms of a milk allergy can vary greatly and include, amongst others:

• Tingling, burning and swelling in the mouth and throat
• Gastrointestinal symptoms such as stomach ache, vomiting, constipation or diarrhoea
• Skin symptoms such as itching, redness or hives
• Respiratory symptoms such as allergic rhinitis, coughing or a runny nose
• Growth retardation in infants is also possible

In rare cases, anaphylactic shock may also occur.

What treatment is used?

The most important measure is to avoid milk and dairy products. Infants and children must switch to special formula, as they require milk as an important source of calcium, protein and vitamin B. People at high risk of anaphylactic shock need an emergency kit.

8 Allergen H: Nuts

What counts as a nut?

Nuts include walnuts, hazelnuts, pecans, macadamia nuts, almonds, pistachios, cashews and Brazil nuts.

What are the triggers?

The triggers for a nut allergy are certain proteins found in the nuts.

What are the symptoms of a nut allergy?

Possible symptoms of a nut allergy include:

• Skin reactions such as itching, a rash and swelling of the face, ears, mouth, tongue, hands or feet.
• Respiratory symptoms such as coughing, a tight feeling in the throat and shortness of breath
• Nausea, vomiting and diarrhoea.
• Dizziness and loss of consciousness

Nuts are also among the most common triggers of anaphylactic shock.

What treatment is available for a nut allergy?

The most important measure is to strictly avoid nuts and all products containing them, including nut oils and nut butters. People at high risk of anaphylactic shock must always carry an emergency kit with them.

9 Allergen L: Celery

What triggers a celery allergy?

The trigger for a celery allergy is certain proteins found in celery.

Where is celery found?

Celery is not only eaten as a vegetable, but is also found in many spices and spice mixes for soups, stocks, tomato juice, sauces and bouillons. Celery may also be present in bacon, salads and crisps, as well as in celery seed oil.

What are the symptoms of a celery allergy?

The following symptoms may occur:

• Skin reactions such as itching, hives or a rash
• Gastrointestinal symptoms such as abdominal pain, nausea or diarrhoea
• Respiratory problems such as a runny nose or asthma

What treatment is used?

The most important measure for a celery allergy is to consistently avoid the allergen.

10 Allergen M: Mustard

What triggers a mustard allergy?

The trigger for a mustard allergy is certain proteins found in mustard. Mustard can be present in many foods.

These include:

• Pickled vegetables such as gherkins
• Curry mixes
• Salad dressings
• Spice mixes

What cross-allergies are possible?

Cross-allergies may occur with Chinese cabbage, rapeseed or beetroot.

What are the symptoms of a mustard allergy?

The symptoms of a mustard allergy may include, amongst others:

• Gastrointestinal symptoms such as abdominal pain, diarrhoea or nausea
• Skin reactions such as itching, hives or eczema
• Respiratory symptoms such as coughing or shortness of breath

These can range up to anaphylactic shock.

What treatment is used?

The most important measure for a food allergy is to consistently avoid the allergen. People at high risk of anaphylactic shock need an emergency kit.

11 Allergen N: Sesame

What is the trigger?

The triggers are certain proteins found in sesame.

In which foods is sesame commonly found?

Sesame is a very common spice and is often found in bread, crispbread and other baked goods, hummus, falafel, salads, marinades and even desserts.

What symptoms occur with a sesame allergy?

The following symptoms may occur:

• Skin reactions such as itching, redness or hives.
• Gastrointestinal symptoms such as vomiting or nausea
• Respiratory symptoms such as coughing or shortness of breath
• Circulatory reactions

In the case of particularly severe allergic reactions, anaphylactic shock may also occur.

What treatment is available for a sesame allergy?

Here too, avoiding the allergen is the most important measure. People at high risk of anaphylactic shock need an emergency kit.

Allergen O: Sulphur dioxide and sulphites

What are these two allergens?

Sulphur dioxide and sulphites are additives and preservatives that are added to many foods.

Where are they found?

Sulphur dioxide and sulphites are found, for example, in dried fruit, dried vegetables, mushrooms, potato products, wine, beer, bread, muesli, meat, soups, sauces, candied fruit and sauerkraut.

What symptoms occur in the event of such an allergy?

Asthmatic reactions are the most common; in rare cases, anaphylactic shock may also occur.

What treatment is used?

The most important measure for a sulphur dioxide or sulphite allergy is to consistently avoid the allergen. People at high risk of anaphylactic shock need an emergency kit.

13 Allergen P: Lupins

What are lupins and in which foods do they occur?

Lupins are plants belonging to the legume family. They are mainly used as an ingredient in bread, pastries, pasta, pizza, gluten-free products and meat substitutes, as well as in liquid seasonings.

What symptoms occur with a lupin allergy?

Skin reactions, breathing difficulties, cramps and even anaphylactic shock have been reported to date.

What treatment is used?

The most important measure for a lupin allergy is to strictly avoid the allergen. People at high risk of anaphylactic shock need an emergency kit.

14 Allergen R: Molluscs

What is the trigger?

The triggers, or the main allergens in molluscs, are substances known as tropomyosins. These are proteins that are not destroyed by heat, meaning that even cooked mollusc meat can trigger allergic reactions.

Which animals are classified as molluscs?

Molluscs include:

• Snails
• Mussels
• Squid

What are the symptoms of a mollusc allergy?

The following symptoms may occur:

• Skin reactions such as redness and itching
• Gastrointestinal symptoms such as abdominal pain, vomiting or diarrhoea
• Respiratory problems such as a runny nose or asthma-like symptoms

In some cases, anaphylactic shock may also occur.

What treatment is available for a mollusc allergy?

Here too, the most important measure is to avoid the allergen. People at high risk of anaphylactic shock need an emergency kit.

Food allergies in everyday life: what do you need to watch out for?

• The most important measure for a food allergy is avoidance, i.e. staying away from the relevant allergen.
• Experts recommend that avoidance be supported by personalised dietary advice.
• People at risk of a severe anaphylactic reaction must carry an emergency kit with them. This is very important in the event of an accidental dietary slip-up.