Mononucleosis is a viral illness
that is usually caused by the Epstein-Barr virus, although it can also be caused by the coxsackie virus. It is transmitted through contact with moisture from an infected individual, such as fluid from his or her mouth or throat. In order to fully review your individual case and the treatment options, it will be important for you to schedule an appointment to meet with your doctor
so that he or she can obtain a full history, perform a physical exam, and run any tests that are indicated.
Having said that, eyelid swelling is a typical complication (or side effect) of mononucleosis. It can persist for many days, and as you know, can be quite frustrating. If it is not bothering you too much, I would recommend waiting for it to resolve on its own without treatment with medications, as it should eventually go away. You could also try using ice packs on your eyelids, which can work for some people. If that is still not helping, a stronger treatment route would be to take a short course of prednisone (an oral corticosteroid), which works quite well for swelling associated with mononucleosis.
Again, it will be important for you to speak with your doctor to review your treatment options and whether or not a short course of prednisone is right for you.