Glandular fever is a type of viral infection that mostly affects young adults. It is also known as infectious mononucleosis, or "mono". Common symptoms include: a high temperature (fever) a severely sore throat swollen glands in the neck fatigue (extreme tiredness) While the symptoms of glandular fever can be very unpleasant, most of them should pass within two to three weeks. Fatigue, however, can occasionally last several months.