Mononucleosis is usually diagnosed based on the patient’s symptoms of fever, sore throat, and swollen lymph glands. The doctor may order blood tests, particularly the mono spot test. This test detects antibodies to the Epstein-Barr virus, but sometimes it is inaccurate (yields a false negative) during the first week of infection. Other blood tests, such as a complete blood count, might be done to see if the number of lymphocytes is higher than normal, which may support the diagnosis. Occasionally, titers of antibodies against the viruses that cause mononucleosis may need to be done to confirm the diagnosis.