Food allergy

Food allergies are less common than some people think. There are often other reasons for the symptoms. With a careful diagnosis, doctors can find out whether there is an allergy, and then treat it in a targeted way. This will enable patients to not have to avoid particular foods unnecessarily. They can often continue to eat those foods.

At a glance

  • With food allergies, the immune system reacts to proteins that are actually harmless as if they were foreign bodies.
  • Even small amounts of a food are enough to trigger the allergy.
  • The symptoms vary widely and may also affect organs.
  • The mucus often swells up in the mouth and throat.
  • Itching, rashes with reddening, and hives are also common symptoms.
  • Around 4 percent of the population suffer from a food allergy.

Note: The information in this article cannot and should not replace a medical consultation and must not be used for self-diagnosis or treatment.

Food allergy: a boy sitting at a table in front of a bowl of peanuts.

What is meant by a food allergy?

Nausea, an ill feeling, or a rash: people with a food allergy always experience the same symptoms. They occur after eating even tiny quantities of the food concerned.

However, food allergies are less common than many believe. There are often other reasons for the symptoms. So a careful diagnosis is important. The doctor can then determine whether there actually is an allergy and, if so, treat it appropriately. If it turns out that no allergy exists, the foods can often continued to be eaten.

What is an allergy?

The video below explains what can trigger an allergy and what symptoms can occur.

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What are the symptoms of a food allergy?

Someone who has a food allergy often reacts when consuming small amounts of a food. There is a wide range of symptoms. Organs may also be affected.

Possible symptoms include:

  • swelling of the mucus in the mouth and throat
  • itching
  • rashes and reddening
  • hives
  • nausea
  • stomach or gastrointestinal problems, for example diarrhea
  • breathing problems

The allergic reaction usually begins within half an hour, but at most a few hours after consuming the food.

A food allergy can also cause an anaphylactic reaction: drop in blood pressure, loss of consciousness, rash, urticaria, itching and swellings in the face are possible symptoms. If swelling occurs in the airways it can cause breathlessness.

With fruit and vegetable allergies, the symptoms tend to be milder, such as rashes. It is more often nuts and shellfish that cause more severe allergic reactions.

Important: Other conditions or intolerances can also trigger symptoms typical of a food allergy. There is a great risk of getting them mixed up. For example, additives and flavorings in foods, such as glutamate, can cause similar symptoms, for example. Stomach problems can also be caused by infections or irritable bowel syndrome. So someone with a possible food allergy should always see their doctor to clarify the situation.

What can cause a food allergy?

With food allergies, the immune system reacts to proteins that are actually harmless as if they are foreign bodies.

Some people have a genetic tendency to have allergic reactions. However, the precise causes of a food allergy are not clear.

Food allergies are typically triggered by nuts, pulses (legumes), cow’s milk, hen’s eggs, soya, wheat, stone fruit, pome fruit, vegetables such as celery or carrots, meat, fish and seafood.

Typical triggers include: 

  • peanuts, walnuts, hazelnuts
  • pulses (legumes)
  • cow’s milk, hen’s eggs, soya, wheat
  • stone fruit and pome fruit
  • vegetables such as celery and carrots
  • fish and seafood
  • meat

Important: Children most commonly suffer allergic reactions to nuts, cow’s milk, soya, wheat, and hen’s eggs. Adults tend more to react to nuts, soya, celery, or seafood. Most sufferers have between one and 3 food allergies.

How common are food allergies?

Around 4 percent of the population in Germany have a food allergy. They can begin at any age. How it progresses varies greatly, depending on the trigger and the age of the person.

In Deutschland haben rund 4 % der Bevölkerung eine Nahrungsmittelallergie.

It is difficult to say how long a food allergy will last and how it will evolve. Children who are allergic to milk protein, wheat or soya have a good chance that their problems will disappear after a few years. This is because the body learns to cope with the substances triggering the allergy.

Someone who first reacts to foods such as fish or seafood when they are of adult age usually finds that the allergy is long-term. Nut allergies also often last longer or for life. Around half of children with a food allergy later develop an allergic asthma or an allergic rhinitis.

The probability that an allergy will be permanent rises along with the severity of the complaints. Significant reactions in allergy tests also point to a lasting allergy.

How is a food allergy diagnosed?

Skin and blood tests, for example, can verify whether someone has a food allergy. Doctors use the tests to see whether the immune system reacts excessively, i.e. allergically, to particular substances.

In a skin test, the skin is gently pricked. A solution with a particular food protein is then applied to that area. If the skin itches or turns red, or if hives appear, an allergy is possible. With blood tests the doctor checks whether the body forms antibodies against a food.

However, these types of tests are usually not enough to identify a food allergy definitively. So a provocation test is also often carried out: with this, the sufferers eat the suspicious food under medical observation.

How can food allergies be treated?

With a food allergy, the main thing is to avoid the trigger food. In the short term, severe symptoms can also be treated with drugs. As a rule, drugs are not used on an ongoing basis with food allergies.

The most severe form of allergic reaction is called anaphylaxis. With this, the entire body reacts and at least two organs are affected simultaneously – for example the skin and the airways or the gastrointestinal tract and the cardiovascular system. Should this type of anaphylactic reaction occur, a special emergency kit is used. Severe symptoms can be treated with the drugs in the kit. They also help prevent any deterioration.

It is also possible to save information about severe allergies in the emergency data record on the electronic medical data card.

For more detailed information, for example on how a food allergy is treated, go to

What else should I know?

There is more information on food allergies at (in German).

  • Biedermann T, Heppt W, Renz H, Röcken M (Ed). Allergologie. Berlin2016. Aufgerufen am 01.06.2020.
  • de Silva D, Geromi M, Panesar SS, Muraro A, Werfel T, Hoffmann-Sommergruber K et al. Acute and long-term management of food allergy: systematic review. Allergy 2014; 69(2): 159-167. Aufgerufen am 01.06.2020.
  • Kurowski K, Boxer RW. Food allergies: detection and management. Am Fam Physician 2008; 77(12): 1678-1686. Aufgerufen am 01.06.2020.
  • Worm, M., Reese, I., Ballmer-Weber, B. et al. Leitlinie zum Management IgE-vermittelter Nahrungsmittelallergien. Allergo J 24, 38–77 (2015).

In cooperation with the Institute for Quality and Efficiency in Health Care (Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen – IQWiG).

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