Mononucleosis
What is Mononucleosis?
Mononucleosis is a viral infection that causes extreme fatigue and flu-like symptoms. Most people call it mono or the kissing disease. The Epstein-Barr virus causes about 90% of mono cases, while cytomegalovirus and other viruses account for the rest.
Mono spreads through saliva and other bodily fluids. You can catch it from kissing, sharing drinks, or being near someone who coughs or sneezes. The virus infects white blood cells and can stay in your body for life, though it usually becomes dormant after the initial infection clears.
Most people get mono during their teens or early twenties. Young children who get infected often have mild symptoms or none at all. The infection typically lasts two to four weeks, but fatigue can continue for months afterward.
Symptoms
- Extreme tiredness that does not improve with rest
- Fever ranging from 100 to 104 degrees Fahrenheit
- Very sore throat that makes swallowing difficult
- Swollen lymph nodes in the neck and armpits
- Swollen tonsils that may have white patches
- Headache and body aches throughout
- Enlarged spleen that can cause upper left belly pain
- Skin rash that appears as small red spots
- Loss of appetite and feeling generally unwell
- Night sweats that soak through clothing
Some people, especially young children, have very mild symptoms or show no signs of infection at all. Others may feel severely ill for several weeks before gradually recovering.
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Causes and risk factors
The Epstein-Barr virus causes most cases of mononucleosis, while cytomegalovirus causes a smaller portion. These viruses spread through contact with infected saliva, blood, semen, or other bodily fluids. Sharing eating utensils, drinking glasses, or toothbrushes can transmit the virus. You can also catch it through blood transfusions or organ transplants, though this is rare.
Teens and young adults face the highest risk because they often have close contact through kissing and sharing drinks. People with weakened immune systems are more vulnerable to severe infections. Once infected, the virus remains in your body forever, usually staying dormant. Stress, illness, or immune suppression can sometimes reactivate the virus, though this rarely causes symptoms as severe as the first infection.
How it's diagnosed
Doctors typically diagnose mononucleosis based on symptoms and a physical exam. They check for swollen lymph nodes, enlarged spleen, and inflamed throat. Blood tests can confirm the diagnosis by detecting antibodies your immune system makes to fight the virus. Immunoglobulin M antibodies show up during active infection, while IgG antibodies indicate current or past infection.
A monospot test provides quick results and looks for specific antibodies that appear with Epstein-Barr virus infection. However, this test may show false negatives early in the illness. A complete blood count can reveal elevated white blood cells with unusual appearance. Talk to your doctor about which tests make sense for your symptoms and timeline.
Treatment options
- Get plenty of rest and sleep at least eight hours each night
- Drink lots of water, herbal tea, and clear fluids to stay hydrated
- Take over-the-counter pain relievers like acetaminophen or ibuprofen for fever and discomfort
- Gargle with warm salt water to soothe a sore throat
- Avoid contact sports and heavy lifting for at least four weeks to prevent spleen rupture
- Eat nutritious foods including fruits, vegetables, and lean proteins when appetite returns
- Avoid alcohol completely while recovering to protect your liver
- Return to normal activities gradually as your energy improves
Antibiotics do not work against viral infections like mono. Your doctor may prescribe corticosteroids if your throat swells severely or complications develop. See a doctor immediately if you experience sharp abdominal pain, difficulty breathing, or symptoms that worsen suddenly.
Frequently asked questions
Most people feel better within two to four weeks after symptoms start. However, extreme fatigue can continue for several months in some cases. Your body needs time to fight off the virus and recover fully. Listen to your body and rest when needed during the recovery period.
Getting mono twice is extremely rare. Once you recover from the initial infection, your body develops immunity to that virus strain. The virus stays in your body forever but usually remains dormant. In people with severely weakened immune systems, the virus can occasionally reactivate and cause mild symptoms.
Yes, mono spreads easily through saliva and other bodily fluids. You are most contagious while you have symptoms, especially during the first few weeks. However, some people can spread the virus for months after recovering. Avoid kissing and sharing drinks or utensils until your doctor says you are no longer contagious.
See a doctor if you have severe sore throat, swollen glands, and extreme fatigue lasting more than a week. Seek emergency care immediately if you experience sharp abdominal pain, which may signal a ruptured spleen. Also get urgent care if you have difficulty breathing or swallowing, or if you feel dizzy and lightheaded.
Focus on easy-to-swallow foods like smoothies, yogurt, soups, and mashed potatoes when your throat hurts. As you feel better, add nutrient-dense foods including fruits, vegetables, whole grains, and lean proteins. These foods provide vitamins and minerals that support immune function. Avoid alcohol completely during recovery to protect your liver.
Most people recover from mono without lasting problems. However, complications can include an enlarged or ruptured spleen, liver inflammation, anemia, and heart inflammation. Rarely, mono can cause nervous system problems or severe breathing difficulties. These serious complications are more common in people with weakened immune systems.
People call mono the kissing disease because it commonly spreads through saliva during kissing. Teens and young adults often get mono this way. However, you can also catch the virus by sharing drinks, eating utensils, or being exposed to coughs and sneezes. Any close contact with infected saliva can transmit the virus.
Both cause severe sore throat, but strep throat comes from bacteria while mono comes from a virus. Strep throat responds to antibiotics and usually improves within days of treatment. Mono does not respond to antibiotics and takes weeks to resolve. Blood tests and throat swabs can help doctors tell them apart.
Yes, children can get mono, but their symptoms are usually much milder than in teens and adults. Young children may have only a slight fever and mild tiredness that parents mistake for a regular cold. Many people get infected as children without knowing it. By adulthood, about 95% of people have antibodies showing past exposure to Epstein-Barr virus.
The monospot test is a quick screening that detects heterophile antibodies produced during Epstein-Barr virus infection. More specific tests measure Immunoglobulin M levels, which rise during recent viral infections. Doctors may also test for Cytomegalovirus antibodies if they suspect that virus caused your mono. A complete blood count shows if your white blood cells look abnormal.