Question

fix the two words that are used incorrectly.

sometimes a completely harmless substance can have an averse affect
on a patient simply because he or she is worried about experiencing a
negative reaction.

Explanation:

1. "Averse" describes a feeling of opposition, but we need "adverse" here, which means harmful or unfavorable, to describe a negative effect.
2. "Affect" is typically a verb meaning to influence. Here, we need the noun "effect," which refers to a result or consequence of something.

Answer:

1. Change "averse" to "adverse"
2. Change "affect" to "effect"

Revised sentence: Sometimes a completely harmless substance can have an adverse effect on a patient simply because he or she is worried about experiencing a negative reaction.