subject: Countdown to Flu 2010: Flu vs. Mononucleosis [print this page] As you can see both the flu and mononucleosis are viral diseases. The treatment for both is rest, oral fluids and medication for the fever. Remember antibiotics are not useful for a virus. Typically patients with mononucleosis have a more severe sore throat and swollen glands called lymph nodes. These swollen glands are found in the neck, and under the arms. Mononucleosis is more commonly found in children and in teenagers since most patients can only get the disease once. Many older adults have already built up a natural immunity from a previous infection preventing them from becoming ill a second time. The flu can infect the same person multiple times since each year it changes slightly. This ability of the flu virus to modify itself is why you need a new flu shot every year. Use iTriage to locate a provider for your flu shot.