Side effects are all effects that occur as a reaction to the administration of a drug. These can be divided into desired and undesired side effects. These are based on observations and reactions of the body to a preparation that deviate from its expected and hoped-for main effect. Byeffects of medicinal products and medical devices are subject to the legal duty of disclosure and must be labeled accordingly. The insufficient effectiveness of a medical preparation does not fall under side effects.
In connection with secondary effects, the interaction with other drugs and substances must also be considered. Side effects are differentiated into those that are typical for the drug and depend on the dosage administered, and those that are unpredictable and independent of the dosage. Both groups can then be further classified into mild to severe byeffects. The percentage frequency of occurrence of certain side effects must also be declared. A distinction is made in five gradations:
- Very rare: The side effect is an isolated case or occurs in less than 0.01% of cases.
- Rare: The incidence is 0.01 to 0.1% of the total cases.
- Occasional: adverse reactions occur in up to 10 of 1,000 patients supplied.
- Common: The frequency of reaction in users is 1-10%.
- Very common: the probability of this secondary effect occurring is more than 10%.
It is the duty of pharmaceutical manufacturers to list in the package insert all known complications of a preparation that may occur during treatment. The producer must be liable for all byeffects not listed in the product information.