2. Benefit-risk assessment

Benefit-risk assessment

The most important task for regulators in assessing new medicines is to evaluate the balance between the benefits and the risks of the medicinal product:

• What are all the good effects, i.e., what are the treatment effects on the disease?

• Are there harmful effects also, i.e., were there any adverse reactions (side effects)?

A certain number of harmful effects can always be expected in a medicine – a medicine can never be completely safe. In a complex system like the human body any medicine interferes with various molecular processes, which will have an effect on different physiological functions and may influence the balance between wanted and unwanted effects.


This means that the adverse reactions from the medicine and how they compare with the effect on the disease should be carefully considered:

  • Are the adverse reactions (also known as adverse drug reactions (ADRs)) acceptable?
  • Do the benefits sufficiently outbalance the risks in treatment?

Benefit-risk balancing cannot easily be put into a formula to calculate. It will depend, amongst other things, on the seriousness of the illness. For example:

  • If the medicine is meant for treatment of mild pain, only a few mild side effects would be accepted.
  • If the medicine is to treat a serious cancer where no treatment is yet available, quite severe side effects may be accepted. This is because the benefits from an increased quality of life or a life-prolonging effect may well outweigh the risks.