Early symptoms of mononucleosis mimic those of the flu, including headache, chills, fever and muscle aches, according to WebMD. Additional early symptoms include severe fatigue and sore throat, which is often severe.
As the illness progresses, mononucleosis may cause swollen lymph nodes, soreness in the upper left abdominal region caused by an enlarged spleen, and jaundice, which causes the eyes and skin to develop a yellow tinge, notes WebMD. A measles-like rash may develop on the skin, often developing suddenly following the administration of amoxicillin, which doctors sometimes prescribe to treat sore throat. In addition, mononucleosis may cause tiny bruise-like areas or red spots inside the mouth, particularly on the roof of the mouth.
It is important to seek medical evaluation when experiencing the symptoms of mononucleosis, reports WebMD. This is particularly true if the symptoms last longer than 10 days or if a severe sore throat lasts longer than two days. Severe pain in the abdomen requires immediate evaluation, since it may indicate a ruptured spleen. Some mononucleosis symptoms may indicate meningitis, including developing a rash with many tiny red spots or developing a rash in conjunction with a headache.
The recovery time for mononucleosis is two weeks, notes WebMD. Most treatment plans for the illness involve bed rest and the administration of medications such acetaminophen and steroids to deal with sore throat pain.