The antonyms for the word "unproblematic" are numerous and expansive. Some of the most commonly utilized antonyms include problematic, complicated, difficult, challenging, complex, thorny, troublesome, and onerous. Other antonyms that can be used in place of unproblematic include vexing, aggravating, irksome, and arduous. Essentially, any word that signifies difficulty or challenge can serve as an antonym for unproblematic. When describing a situation or experience, choosing the appropriate antonym can help to accurately convey the level of challenge, difficulty, or complexity involved. Whether describing a task, relationship, or situation, utilizing the appropriate antonym for unproblematic can help to provide detail and context.