Which of the following symptoms is NOT typically associated with mononucleosis?

Diarrhea is not typically associated with mononucleosis. The condition, commonly caused by the Epstein-Barr virus, primarily presents with symptoms such as fever, swollen lymph nodes, and persistent sore throat due to the infection's effect on the lymphatic system and throat tissue. These symptoms stem from the body’s immune response to the viral infection.

In contrast, diarrhea is more commonly related to gastrointestinal infections or conditions affecting the digestive system rather than viral infections like mononucleosis. Thus, while the other symptoms listed directly relate to the clinical presentation of mononucleosis, diarrhea does not fit the typical symptom profile associated with this illness.