Mononucleosis, or more properly, infectious mononucleosis, is caused by the Epstein Barr virus, a herpes virus related to the agents that cause cold sores and chicken pox. Most people get mono at some point in their lives, usually during childhood and, usually, the disease is so mild that youngsters don't even know they're infected. The virus then stays in the body for life, usually causing no further trouble. It seems that the older you are when you first catch mono, the worse your symptoms can become. Some people, who are run down or whose immune systems are depressed, can get quite sick with mono.
Symptoms typically include fever, sore throat, swollen lymph nodes and exhaustion. The fatigue often can be overwhelming, keeping people in bed for several weeks.
The best treatment is rest, at least for the duration of the fatigue - usually a week or two. To relieve the sore throat, drink lots of fluids, gargle with salt water and take Tylenol -- not aspirin. Because of the risk of Reye's Syndrome, children and teens with fever should not be given aspirin. (If your throat is so sore that you can't talk, your doctor may prescribe a syrupy lidocaine gargle.) I would also suggest taking astragalus (Astragalus membranceous), a traditional treatment in Chinese medicine for colds and flu with immune-boosting effects. Take two capsules twice a day unless the product directs otherwise. Echinacea (Echinacea purpera) can also help - the dose is a teaspoon of tincture in water four times a day or two capsules of freeze-dried extract four times a day until symptoms disappear.
In addition to treatment, be sure to wash the dishes and utensils used by people with mono - and don't share food with them. The virus is passed through saliva, which is how mono earned its nickname "the kissing disease."
As for continuing to work if you have mono - that depends on the severity of your symptoms. You may recall that speed skater Chris Witty won a Gold Medal at the 2002 Olympics despite having mono. Of course, most people don't have the motivation and stamina of Olympic athletes and it is best to avoid sports, exercise and other physical activities for about 3 to 4 weeks after infection starts. Moving around too much puts you at risk of rupturing your spleen so wait until you get the go-ahead from your doctor before resuming physical activities.
I don't advise pushing through viral fatigue in order to work, because you'll probably just prolong your recovery. You would be better off resting until the fatigue ebbs and your energy returns.
Andrew Weil, M.D.