Your teen is really dragging, complaining of fatigue, a sore throat and feeling feverish. Worse, none of the symptoms seem to be improving.

Before you pass it off as adolescent malingering, consider that it could be mononucleosis, aka mono, or “the kissing disease.” Teensand young adultsages 15 to 24 are prime targets, though mono can strike anyone, at any age. Here's how to figure out what your teen (or you) may have.

How to tell if it's mono

"Anyone who has true mono is infected by the Epstein-Barr virus," says Jason Womack, MD, assistant professor of family medicine at Robert Wood Johnson Medical School at Rutgers, the State University of New Jersey. Some of the symptoms, especially the fatigue and sore throat, can mimic those of other viruses. But mono infections are typically accompanied by other symptoms, including:

  • Enlarged tonsils
  • Small blotchy spots on the palate (roof of the mouth), caused by tiny hemorrhages
  • Enlarged lymph nodes on the neck and armpits
  • Rash
  • Swollen liver, spleen or both (less common)

According to the Centers for Disease Control and Prevention (CDC), the symptoms may develop over time and not all at once.

Symptoms may vary by age, Womack and others have found. College age students most often have sore throat, enlarged lymph nodes and fatigue, according to a 2013 study, Womack says. His update on mononucleosis was publishedMarch 15 in the journal American Family Physician.

About one in four adults over age 60 who get mono develop jaundice, compared to less than one in 10 young adults. And older adults are less likely than younger ones to have enlarged lymph nodes and sore throats.

Plenty of people will get infected with the Epstein-Barr virus at some point in their life — about 95 percent, in fact — but most of them won’t get sick from it. Only about 30 to 50 percent of people infected go on to develop mono.

How do you get infected?

The virus belongs to the herpes virus family. It's spread mainly by direct saliva contact, Womack says. So the ''kissing disease'' name is earned. Besides kissing, teens often engage in the unhealthy habit of sharing drinks, he says, and the virus can be transmitted when saliva is exchanged that way.

Zeroing in on a mono diagnosis

A mono diagnosis is usually made based on symptoms, though your doctor may decide to order blood tests to confirm the diagnosis. One test, called heterophile testing, looks for a type of antibody, known as hetrophile antibody, made by the body to fight the infection. However, you can easily get a false negative from this test if it's done in the first couple weeks after becoming infected, Womack says.

Typically more accurate is EBV-specific antibody testing. These tests look for immunoglobulin M or G antibodies. They're more expensive and takes longer, however.

Recovering from mono

Rest is the usual treatment, Womack says. "Anti-viral drugs do not seem to decrease the severity or course of the disease," he says.

Oral steroids, which decrease inflammation and ease throat pain for a short time, can be used, Womack says. But they don't work any better than other medicines for the throat pain, he says.

Recovery time varies. It typically takes about four weeks to feel better, according to the CDC. However, it takes months for some, Womack has found.

Complications are rare but can be serious. Spleen rupture is a possibility and a concern, he says. To decrease the risk, he insists anyone with mono avoid vigorous activity for 21 days."Only about 1 percent will have spleen rupture," he says, "but the first three weeks is the highest risk [for it]." During the three weeks after diagnosis, he rules out such activities as competitive sports and weight lifting.

Does the mono virus ever leave you?

Infection with the Epstein-Barr virus is lifelong, according to the American Cancer Society. For most people, however, it does not cause serious problems,though infection with the virus has been linked with an increased risk of getting certain cancers, including cancers in the back of the nose and Burkitt lymphoma, a cancer of the lymphatic system.

Is It Mono or Something Else?The infection may also be linked to Hodgkin lymphoma and some types of stomach cancer. However, very few people who have ever been infected with the virus will go on to develop these cancers, the society says.

What are the chances that if you have mono, it will come back again and again or become chronic? Not likely, according to the Mayo Clinic. The virus does stay in your system, but in most people it lies dormant after the initial infection. Only rarely do the symptoms come back months or years after the initial infection. The possibility of having symptoms again is more likely if you have a compromised immune system, as people with AIDS do.

Rarely, some people develop a chronic active infection, in which the symptoms last more than six months. If that happens, it's crucial to get checked out by your doctor, who can decide whether ongoing treatment is needed. It's also important to rule out other conditions, such as hepatitis, that may be causing your symptoms. 

Kathleen Doheny is a Los Angeles journalist specializing in health, behavior and fitness topics.