Pseudo allergy

Classification according to ICD-10
T78.9	Undesired side effect, unspecified
ICD-10 online (WHO version 2019)

The pseudoallergy (synonymous pseudoallergic reaction ) describes an intolerance reaction, the clinical symptoms of which are very similar to a classic allergic reaction , but without an immunological reaction being detectable. The most common triggers are drugs and food additives .

Since an allergy, a pseudo-allergy or an intolerance can cause similar symptoms, these terms are undifferentiated in common parlance and are often incorrectly used synonymously. As long as the diagnosis is not confirmed, it would be more correct to use the neutral terms intolerance , hypersensitivity reaction or undesirable side effect .

Pathophysiology

Schematic comparison between allergy and pseudoallergy

In the case of pseudoallergy, the allergy-like symptoms are triggered by non-specific activation of mast cells . When mast cells are activated and degranulate , they release a number of inflammatory mediators (e.g. histamine ). An inflammatory reaction develops, which manifests itself in allergy-like symptoms.

While the mast cells are activated specifically in allergies, namely by the fact that certain allergens can bind to surface-bound antibodies , mast cell activation in pseudoallergies is non-specific, i.e. without the involvement of the surface-bound antibodies.

A differentiation from pseudoallergy is intolerance , which can also cause allergy-like symptoms. Intolerance is a metabolic disorder. The body cannot metabolize certain substances or cannot metabolize them sufficiently, mostly due to an enzyme defect .

Triggering substances

A number of substances are able to activate mast cells unspecifically:

• certain drugs , as an undesirable side effect (see also intolerance (medicine) )
  • radiological contrast media
  • nonsteroidal anti-inflammatory drugs (NSAIDs), such as B. acetylsalicylic acid (ASA), then also known as NSAID intolerance, ASA intolerance syndrome, AERD (Aspirin®-exacerbated respiratory disease), prostaglandin synthesis inhibitor intolerance or analgesic asthma syndrome
  • opiate
  • certain muscle relaxants
  • Pentamidine
  • the dextran used in plasma expanders
• certain substances contained in food (this is also referred to as food intolerance ):
  • Lectins , e.g. B. in strawberries
  • Salicylates , e.g. B. in apples or apricots
  • some preservatives , e.g. B. benzoic acid or sorbic acid
  • some acidulants

Clinical pictures

Pseudoallergies have allergy-like symptoms, such as: B .:

• Swelling, redness and itching of the mucous membranes in the mouth and throat
• Runny nose ( rhinitis )
• Discomfort in the gastrointestinal tract (gastrointestinal symptoms)
• Hives ( urticaria )
• Angioedema
• Circulatory reactions

A characteristic of pseudoallergies is a dose-effect curve, which often cannot be observed in allergies. In this way, small amounts of histamine-releasing substances or foods containing histamine can be tolerated without causing symptoms. As the amount of histamine-releasing substances or histamine ingested increases, the severity of the symptoms increases.

Because the pseudoallergies are non-immunological reactions, i.e. they are not mediated by specific antibodies, they can occur as soon as they come into contact with histamine-releasing substances or foods with high histamine content. A diagnosis of pseudoallergies can therefore not be made by measuring antibodies in blood samples.

As undisputed as a possible connection between all these diseases is, it is also unclear to what extent food ingredients are responsible for the complaints mentioned. The figures for urticaria vary from under 1 to over 50 percent.

Web links

• S. Dölle, J. Grünhagen: Pseudoallergies , instructions and tips for a pseudoallergenic diet. (PDF) European Foundation for Allergy Research (ECARF)
• AWMF register 013/028 (PDF), S3 guideline of the German Society for Allergology and Clinical Immunology (DGAKI) u. a .: Urticaria (as of 04/11)
• AWMF register 061-021 (PDF) S2K guideline of the German Society for Allergology and Clinical Immunology (DGAKI) u. a .: Guideline for allergological diagnosis of hypersensitivity reactions to medicinal products (as of 12/2014)

Individual evidence

1. ^ Pseudoallergy In: Roche Lexicon Medicine , 5th Edition. Urban & Fischer Verlag / Elsevier 2006, ISBN 3-437-15156-8 , Gesundheit.de.Retrieved on June 12, 2016.
2. ↑ Intolerance to food components . ( Memento of the original from June 12, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Federal Ministry of Education and Research; accessed on June 12, 2016. 
3. ↑ Diagnostic procedure if a pseudoallergic reaction to food ingredients is suspected . (PDF) Guideline of the German Society for Allergology and Clinical Immunology (DGAKI), the Medical Association of German Allergologists (ÄDA) and the Society for Pediatric Allergology and Environmental Medicine (GPA); accessed on June 11, 2016.

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !