Medication allergies

Allergies are caused by defensive reactions of the body. This occurs when foreign, usually harmless substances are identified as harmful or dangerous and fought against by immune reactions. The development of an allergy takes place in several steps. The first contact usually leads to sensitisation. The second contact leads to an allergic reaction in which certain defence substances of the body (antibodies: e.g. IgE) are involved. Even contact with minute amounts of this foreign substance can be sufficient to trigger an allergic reaction. An allergic reaction can be of varying severity. The range of symptoms is correspondingly wide and ranges from itching, a stuffy nose and rashes to circulatory and respiratory arrest. A distinction is also made between immediate and late reactions. Hereditary factors as well as environmental influences play an important role in the development of allergies.

Substances that trigger allergies are called allergens.

Frequent allergens

  • Foodstuffs (e.g. peanuts, soya)
  • Medicinal products (e.g. antibiotics, vaccines)
  • Inhalation allergens (e.g. flower pollen)
  • Insect poisons (e.g. from bees)

In some cases, an immune reaction can also be caused by contact with substances that resemble an allergen in structure and protein structure. This special form of intolerance reaction is also known as a “cross-reaction”. You should therefore inform your doctor or pharmacist if you know that you suffer from an allergy or drug intolerance.


Pseudo-allergy/intolerance is an intolerance reaction in which the symptoms can be very similar to those of an allergy. The pseudo-allergy, however, occurs without a previous sensitization phase and without the involvement of the immune system. In the case of intolerance, the intolerance reaction is dose-dependent.

Enzyme defects can also lead to intolerance reactions. For example, a deficiency of a certain enzyme (lactase), which is responsible for the breakdown of lactose, can lead to hypersensitivity reactions if lactose-containing drugs or foods are taken or consumed.

What should I bear in mind if I have an intolerance to medicines? 

  • In the event of known intolerance to certain drugs or drug ingredients, please inform your doctor or pharmacist. Even if you come into contact with similar substances, an intolerance reaction (cross reaction) may occur.
  • Before using or applying medicinal products, it is essential to read the package leaflet.
  • Section 2 of the package leaflet contains a detailed description of the circumstances under which a medicine should not be taken.
  • All active ingredients and other excipients of a medicinal product are listed in the package leaflet in section 6 ("Contents of the pack and other information"). The outer packaging does not necessarily show the complete list of all ingredients. Since drug packaging can be very small, it would not be possible to include the complete list of all ingredients on the outer packaging.

Further inquiry note