10 Warning Symptoms of Mononucleosis (Mono)

Mononucleosis Symptoms


Infectious (Mono) is an illness caused by several viral agents, most commonly the Epstein-Barr virus (EBV). It is most common in children and young adults. Mononucleosis symptoms are slow to appear hence many people become carriers without their knowing.

It is an infectious disease caused by the Epstein-Barr virus, a type of herpesvirus. Infection with Epstein-Barr virus (EBV) is common, but not everyone who gets it gets mono. A lot of people have been exposed to the virus by the age of 40 but only 15–20% of teenagers and about 40% of exposed adults actually become infected.

It is also known as glandular fever, Pfeiffer’s disease, Filatov’s disease, and the kissing disease.

There is no vaccine for mono yet.


The virus can be transmitted through direct contact with an infected person’s saliva. Kissing is the main way it spreads. Using a sick person’s utensils can also transfer the virus from one person to another. In some rare cases, it can be transmitted through blood and semen. Scientists are still determining if breastmilk can also be affected.

It is less contagious than the common cold. People with mono don’t usually exhibit coughing or sneezing symptoms, so they’re not spraying virus-containing droplets of saliva into the air.

Mono is less contagious than the common cold or flu.

The EBV virus gets into the body unnoticed for a number of weeks before any symptoms of infection start to show. That is when the virus is most likely to spread among people.

Those infected with the virus carry it within their bodies for life, even after the symptoms of mononucleosis stop and even if they showed no symptoms at all. The virus stays dormant and can be activated in certain cases. The virus then finds its way to the saliva. The person then becomes a carrier for this disease, even if they have no symptoms. 


Mono is primarily diagnosed first by physical examinations of the symptoms which can later be confirmed with blood tests for specific antibodies.


The best form of treatment for those sick with mononucleosis is getting plenty of rest and fluids, most especially during the time when the symptoms are severe.

There are no specific medicines for this disease. Although many physicians would prescribe medicines like acetaminophen or ibuprofen to help ease the discomfort brought by some of the symptoms.

Antibiotics are of no use since mononucleosis is a viral infection and not caused by bacteria.


Mono has a very long incubation period. The symptoms of mononucleosis usually show up 4 to 6 weeks after the infection. Teens and young adults are most likely to experience mono with all of its signs and symptoms. Children, on the other hand, may experience fewer symptoms and the infection often gets unrecognized.

Signs and symptoms of mononucleosis may include some or all of the following:

1. Fatigue

Fatigue is one of the earliest symptoms of mononucleosis.

It is normal for a person to feel tired from time to time but what’s not normal is the constant feeling of being exhausted. No amount of nap or a good night’s sleep can wipe the rundown feeling. If a person also starts to notice that they sleep more and wake up feeling pain in some parts of the body, chances are they might have caught mono.

Although there may be many other factors that can cause exhaustion, mono simply wipes out a person. The level of exhaustion is so severe that it becomes debilitating. 

Most people have the virus dormant inside their bodies for years. It lodges permanently in an individual’s white blood cells or lymphocytes, and sudden stress can lead to its reactivation. In addition to that, viral infections can wreak havoc on a person’s health months or years later in life and they can be difficult to eradicate once they get a foothold in their system.

It is important to remember that mono may trigger chronic fatigue, but it does not cause chronic fatigue. Fatigue due to mono-infection usually resolves within 3 months and uncommonly lasts for longer than 6 months.

2. Pain in the upper left abdomen

People diagnosed with mono often describe soreness in their abdomen early into the sickness. Pain in this area indicates spleen or liver enlargement, which often swell and sometimes even rupture.

The spleen is part of the lymphatic system. It helps the immune system by producing white blood cells and helps in the creation of antibodies. White blood cells are the body’s first line of defense against bacteria and viral infections. The spleen also filters blood by removing abnormal blood cells from the bloodstream.

Infection is one of the primary causes of an enlarged spleen. This condition is called splenomegaly.

The spleen may overwork during an infection.  This can create an excess of red blood cells and platelets. These, in turn, could eventually clog the spleen, affect normal functioning and cause enlargement.

Doctors would advise people with this symptom to refrain from doing any roughhousing, contact sports or hobbies for at least four weeks after symptoms begin.

3. Sore throat

While a sore throat may stem from other diseases like a cold, flu or strep infection (strep throat), this can also be an early symptom of mononucleosis.

When a person has mono, the throat would appear red, itchy and swallowing becomes painful. White spots or pus may also appear on the tonsils making it look very similar to strep throat. The pain is severe around 3-5 days and gradually resolves within the next 7-10 days.

Doctors can conduct tests to tell if the pain is caused by EBV virus infection or any other disease with a similar symptom. Once the true underlying cause is determined, the correct course of treatment can be administered. Early detection and proper medication bring fast relief for the symptoms and prevent complications.

4. Fever and chills

Fever is one of the early symptoms that a person may have mononucleosis. Mono can bring extremely high fevers like colds and flu. Typically, with mono, the fever may range from 101°F (38.33°C) to 104°F (40°C). The fever may last for several days and would steadily get better afterward.

A lot of patients experience fever peaks in the afternoon or evening. This could last a few days or weeks depending on how a person’s immune system does in fighting the infection.

Fevers help the body resolve the infection happening within the body. It is the immune system’s way of fighting it.  The hypothalamus is a part of the brain that regulates the body’s temperature. Sometimes the hypothalamus will reset the body to a higher temperature in response to an infection, illness, or some other cause. The high temperature makes it hard for germs to live within the body.  

As the body temperature goes up, the person may feel cold until it levels off and stops rising. This is more known as the chills.

5. Sore and stiff muscles

Muscle soreness is another one in the list of uncomfortable and common symptoms present in a mono-infection. It is characterized by sharp, intermittent pains or a dull but persistent ache. Muscle weakness (myositis) may also be experienced.

The muscle pain (myalgia) is caused by the body’s autoimmune reaction to the viral infection. When such infections occur, the immune systems send white blood cells to fight it. This often results in inflammation which can leave the muscles in the body feeling achy and stiff.

Myalgia is just one of the unpleasant side effects of the immune system doing its job.

Muscle pain can also be sparked and made worse by other symptoms of the disease.

6. Swollen lymph nodes in armpits and neck

The lymph nodes located in the neck and armpits swell and cause pain when they are gently pressed. This is another telltale symptom that a person has caught mono.

Lymph nodes are small glands that filter the lymph liquid or the clear liquid that circulates through the lymphatic system. It traps bacteria, viruses, and other foreign substances, which are then destroyed by special white blood cells called lymphocytes.

When the Epstein-Barr virus invades the body, the lymph nodes are set into action.  The lymphocytes attack the viruses. During an infection, the body makes more of those immune cells and that causes the swelling. The lymph nodes will swell from an infection in the area where they are located.

When lymph nodes swell in two or more areas of the body, it is called generalized lymphadenopathy. 

7. Loss of appetite

Loss of appetite is one of the main symptoms of mono. This symptom is closely linked with other symptoms of mononucleosis.

Eating is made more difficult due to the fatigue, throat pain, swollen neck glands, fever, and weakness in the early stages of the infection.

In addition to that, an enlarged spleen causes discomfort, a feeling of fullness and pain in the abdomen which can further decrease appetite.

When a person is infected with the mononucleosis virus, eating becomes the last thing that they’d want to do. Aside from the other symptoms that contribute to the loss of appetite, the infections lead to higher levels of circulating TNF-alpha (an inflammatory cytokine), which promotes appetite suppression.

8. Night sweats

Some patients would complain that they are experiencing night sweats. It would later be discovered that their bedroom was just unusually hot that night or that they were wearing too many bedclothes.

True night sweats are severe hot flashes occurring at night that can drench your clothes and sheets and that are not related to an overheated environment.

Night sweats are common in sick people especially if there is a fever involved.

However, sweating often and profusely at night could also be a sign of mono. Night sweats are one of the early symptoms of the virus, particularly in the initial weeks after diagnosis

Secondly, mono is sometimes accompanied by sleeping difficulties that could cause profuse sweating at night. The lack of sleep due to night sweats can further exacerbate other symptoms of the disease like fatigue and headaches.

9. Skin rash

Mono can cause a pink or red splotchy, measles-like rash to appear on the skin. It is a less common symptom of mono; however, it may be a sign of the infection.

Mono has very similar symptoms to strep throat. Antibiotics may be given for the sore throat infection if the disease is mistakenly diagnosed as a strep throat infection. Some people test positive for strep when they have the Epstein-Barr virus.

These skin rashes are an effect of the antibiotics. Antibiotics are not normally used to treat mono since it is a viral infection. The rashes may become itchy at times. Antihistamines, like Benadryl, and topical steroids can be used to relieve the itching.

The rashes would go away on its own as a person recovers from mononucleosis.

10. Jaundice

People with mono may show signs of jaundice. It is a rare symptom of the disease. It is a sign that the Epstein-Barr virus is causing liver problems as well. The mild inflammation in the liver causes jaundice. This condition is called hepatomegaly.

Jaundice is the term used for the yellowing of the skin and the whites of the eyes. This could also affect some body fluids. This occurs when the body does not process bilirubin properly due to liver problems.

Bilirubin is the yellow-colored waste material that remains in the bloodstream after iron is removed from the blood. The liver filters this out of the blood.

While the virus may cause minor liver abnormalities, these probably won’t require special treatment and liver function should return to normal as the patient recovers.

If a sick person shows symptoms that resemble the ones mentioned, it does not automatically mean it is mono. Many viral illnesses can cause a similar picture. But if the illness persists for more than a few days with the persistence of sore throat, swollen glands, and fever, a visit to the doctor should be set as soon as possible.

Although the symptoms can be really uncomfortable, they tend to resolve on their own without any long-term effects, except for when complications arise due to the virus. Most adults have been exposed to the EPV virus and have built up antibodies. This means that they’ve become immune to it and won’t likely get mononucleosis.