Side effects of veterinary medicines
What is a side effect?
A side effect, also called an adverse event or adverse reaction, is an unwanted and harmful reaction to a medicine.
Information about known side effects and their frequency can be found in the product leaflet accompanying the medicinal product. This information is also described in the authorised Summary of Product Characteristics (SPC) for the medicinal product. SPC’s can be found either on the Danish Medicines Agency’s website or through the European Medicines Agency’s website.
When it comes to veterinary medicinal products, in addition to adverse events in animals, we also consider any adverse event happening to the human who is handling and administering the medicine (known as ‘user safety’).
It is very important to know, that it is not necessary to be certain that the medicine caused the side effect in order to report it – a suspicion is enough. A thorough evaluation of the causal association is always performed before reports can lead to further action.
What is lack of efficacy?
Lack of efficacy of a medicine means that the medicine did not have the expected effect compared to what is described in the product information, even though the instructions regarding storage, handling and administration of the medicine has been followed.
The product information describes what the veterinary medicinal product has been authorised to treat or prevent, and at what time following treatment the effect can be expected. It also includes information on how to store and administer the medicine to the animal.
The balance of benefits and risks
In order to authorise a new medicine for animals it is crucial that the risks related to treatment do not outweigh the benefits of the medicine.
Therefore, in order for this benefit-risk balance to remain positive, it is important to know which side effects can be expected and how often they occur, but also if the product is not as effective as intended. Both factors – side effects and lack of efficacy – may change the benefit-risk balance.