Some drugs or medicines have both adverse events and side effects. These two
terms are usually interchanged or used instead of the others. Thus, we may not be aware of
the difference between adverse events and side effects. However, there is ample difference
in the meaning of both terms.
An adverse event is an undocumented therapeutic/pharmacological event that is
either unpredictable or a dangerous reaction to the medication. They cannot be studied
during drug development because they are unique to dose, patient and possible interaction.
The dose-dependent adverse event can be mild, moderate or severe. The patient-specific
susceptibility factors such as drug allergies, intolerance will also cause adverse events.
A side effect is a documented therapeutic effect that occurs when the treatment
goes beyond the desired effect or a problem occurs in addition to the desired therapeutic
effect. Unlike adverse events, side effects are predictable by healthcare professionals. This is
because they can be studied during clinical trials and drug development to identify the
distinctive advantages of the drug versus the risks. Thus, patients are told to be aware of the
side effects that may occur after taking the medication. Fortunately, side effects are able to
resolve on their own after taking several weeks.
Knowing the difference between these two terms is important for healthcare
professionals so that we can consult our patients correctly. For instance, side effects will go
away with time and should not be too concerned about it while adverse events should seek
medical treatment immediately.