All medication comes with side effects (also called adverse events) which are defined as effects that the drug may have other than the intended effect. When a drug is first developed one of the most important characteristics to investigate are the number and intensity of side effects that they cause and this can only really be achieved by testing on people - these tests are part of phases 2 & 3 of a standard clinical trial. Sadly these trials do not pick up every side effect as they are limited in size and scope.
- One of the criteria for a trial is that the person testing is not taking any other drug whereas we know in the real world most people with a chronic illness will be taking more than one drug at a time! Drugs interact with each other and new side effects emerge as a result
- Some side effects are rare so they are not reported until thousands of people have taken the drug
It helps everyone if all side effects are reported each time they are experienced. This used to be the job of clinical staff and still is but we can all now join in! In EU the MRHA have set up a website for everyone to enter new side effects and in the US the FDA have a similar website.