Final answer:
Adverse drug reactions can result from overdose, the formation of toxic metabolites, and allergies, including various types of hypersensitivity reactions.
Step-by-step explanation:
Adverse drug reactions can be caused by several factors, such as:
- Overdose, which refers to ingesting prescription or over-the-counter medicines in doses that are too high or overdoses of illegal drugs.
- Formation of toxic metabolites as the body processes the ingested chemicals, which can lead to medical conditions like metabolic acidosis.
- Allergy, as in the case of hypersensitivity reactions, where the immune system overreacts to a substance that is otherwise harmless to most people. For example, type III hypersensitivity is induced by the accumulation of immune complexes in tissues and small blood vessels.
In the context of drug use and reactions, it is also important to understand concepts such as tolerance, where a drug user requires more of the drug to experience the same effects, and anaphylactic shock, a severe allergic reaction that can be life-threatening, treated with drugs like epinephrine.