What is a side effect?

• A. An unwanted physical or mental effect caused by a drug
• B. The primary therapeutic effect
• C. A placebo effect
• D. A beneficial long-term effect

Answer: (A)

A side effect is an unwanted physical or mental effect caused by a drug. It isn’t what the medicine is aimed to do, but rather a secondary result of how the drug acts in the body. Side effects arise because drugs can interact with multiple receptors and processes, so even helpful medications can cause mild but undesired changes in how you feel or function.

This definition fits best because it emphasizes the unwanted nature and the drug-related cause. The primary therapeutic effect is the intended benefit of the medicine, not a side effect. A placebo effect is a psychological response to thinking you’re taking medicine, not a direct drug-related side effect. A beneficial long-term effect describes a positive outcome over time, which isn’t the same as an unwanted side effect.