An allergy is an excessive reaction by the immune system to a particular substance.


An allergy is an excessive reaction by the immune system to a particular substance. These allergens, which vary widely in nature, are harmless to people who don't suffer from allergies. They can, however, cause redness, itching and sometimes life-threatening respiratory and cardiovascular complications. This reaction can be largely prevented by identifying and avoiding the allergens.


  • Mucous membranes
  • Airways
  • Skin
  • Gastro-intestinal tract
  • General symptoms
  • Sometimes accompanied by psychological symptoms
  • Life-threatening general reactions
    • Respiratory arrest
    • Massive drop in blood pressure which can cause a circulatory collapse (anaphylactic shock)
    • Loss of consciousness
  • Time of occurrence
    • Seasonal (e.g. when the pollen count is high)
    • Throughout the year (e.g. after touching animals)

Causes and treatment


Excessive reaction by the immune system to specific substances in the world around us that are harmless to non-allergy sufferers (more or less the opposite of immune deficiency).

Promoting factors
  • Genetic susceptibility
  • Babies who aren't breastfed or who are breasfed for a short time only (<4 months)
  • Allergies are on the rise; possible reasons:
    • Increase in air pollutants
    • More contact with genetically modified substances
    • Stricter hygiene measures (this limits immune system training); children living in the city tend to have more allergies than children in the country
Allergens (list is not exhaustive)
  • Inhaled allergens
    • Breathed in
    • Among the most common causes of allergies
    • Grass and flower pollen, dust, mould fungi, etc.
  • Contact allergens
    • Skin contact triggers reaction
    • Nickel, leather, latex, cosmetics, laundry detergents, adhesives, plants or animals
  • Food allergens
    • Allergic reaction triggered in the gastrointestinal tract during the digestive process
    • Typical foods: eggs, nuts, chocolate, soya, fish, cow's milk
    • Medication
  • Injected allergens
    • Allergen enters the body after a sting
    • Poison from an insect or other animal
    • Medication

Further treatment by your doctor / in hospital

Possible tests
  • Physical examination (focus on skin, airways)
  • Blood test
  • Oxygen saturation
  • Allergy test (to identify the substances that trigger a reaction)
Possible therapies
  • Suppression of the allergic reaction (adrenaline, antihistamines)
  • Treatment of the general symptoms
  • What is known as hyposensitisation or desensitisation
    • Organism is made more resistant (e.g. allergy to bee venom)

What can I do myself?

  • Babies <4 months
    • Full breastfeeding
    • If mother's milk is not enough: give them “hypoallergenic” infant food
  • Babies >4 months
    • Start introducing solids
    • Avoid typical food allergens (cow’s milk, eggs, nuts, chocolate, soya and fish)
  • Generally: identify allergens
    • Classify symptoms by location, time and situation
    • If necessary, eat the suspected trigger food on its own and compare the reaction
  • Persons at risk: always carry an emergency kit prescribed by the doctor (rescue inhaler for asthma)
  • Alternative methods can make a contribution to treatment
Avoid contact with the allergens (exposure prevention)
  • Pollen
    • Follow current reports in the media
    • Plan sports and other activities accordingly
    • During the pollen season, regularly wash your hair at night and don't take off your street clothes in the bedroom
    • Air rooms only briefly
  • House dust mites
    • Don’t have carpets/curtains in the home
    • Special covers for feather beds and mattresses
    • Don't use humidifiers (mites enjoy high humidity)
    • Air rooms regularly and keep the temperature cool (below 20°C)
  • Mould fungi
    • Cool and dry room temperature
    • Plants grown in soil often carry fungi that trigger a reaction in people who are allergic to mould fungi
    • Cheese with edible mould (Brie, Gorgonzola) doesn't have to be avoided
  • Animals or their particles (e.g. hair)
    • Don’t keep pets that are known to trigger an allergy
    • If contact can't be avoided, take medication as a preventive measure
  • Contact allergens
    • Avoid bringing the skin or mucous membranes into contact with the allergen
    • Typical contact allergens: nickel, leather, perfume, adhesives, latex
  • Food allergens
    • Check food ingredients against the label

When to see a doctor?

  • Severe allergic reactions
  • For allergy tests
    • Identify the substances that trigger a reaction
    • Often make it possible to deliberately avoid allergens
  • For hyposensitisation or desensitisation

Further information

For children's diseases: Swiss Lung Association (Lungenliga Schweiz)

aha! Swiss Allergy Centre (aha! Allergiezentrum Schweiz) CSS has joined forces with the aha! Swiss Allergy Centre to offer an anaphylaxis course for adults, young people, and parents of affected children.


allergy, allergic reaction

Exclusion of liability

CSS offers no guarantee for the accuracy and completeness of the information. The information published is no substitute for professional advice from a doctor or pharmacist.