Antonyms for the term "mellowing out" include "intensifying," "energizing," "agitating," "exasperating," "irritating," and "frustrating." These words refer to actions or effects that are entirely different from the idea of "mellowing out," which suggests a state of relaxation, calmness, or peacefulness. "Intensifying" refers to the act of making something stronger, "energizing" means intrinsically encouraging activity or enthusiasm, and "agitating" suggests the opposite of being calm, which is to arouse or incite strong feelings. Using these words as antonyms for "mellowing out" drives home the point that the concept is the opposite of distress or heightened emotion.