Any time you take any medication (or any substance at all, for that matter) there is the possibility of side effects. Generally, one doesn't go around consuming pills just to check their body's reaction.

When a doctor takes your medical history, you will be asked about previous allergic reactions. A history of allergies suggests the likelihood of adverse reactions to new drugs you might receive in treatment, among other things.

Right now in the North American continent, we need KI like a fish needs a bicycle.....