What Are the First Mono Symptoms?

There's almost nothing worse than waking up and feeling sick! While you may be experiencing something as simple as the flu or a common cold, your symptoms could also signify another common disease: mononucleosis.

One of the most common first symptoms of mono is severe fatigue that just won’t go away. (Image: Squaredpixels/E+/GettyImages)

If you've been around someone with mono or are experiencing the symptoms detailed below, contact your doctor. Physicians may suspect mono based on symptoms, but a blood test will help confirm the diagnosis.

What Is Mono?

Mononucleosis (aka mono) is an infectious disease caused by the Epstein-Barr virus (EBV) and is also sometimes referred to as "the kissing disease." That's because viral infection transfers from person to person through saliva or through close contact with an infected individual.

Most commonly seen in young adults and teens (though adults can certainly contract it too), this virus attacks the immune system and can lead to a variety of different symptoms.

First Mononucleosis Symptoms

While it's easy to confuse mono with other illnesses, several telltale signs and symptoms can help you identify this common disease.

1. Fatigue

Generally, the first thing most individuals infected with mono experience is a general feelings of sickness and extreme fatigue. These symptoms begin about a month to six weeks after exposure to the virus, according to the American Academy of Family Physicians.

Although an individual with fatigue feels the need to sleep, the condition includes more than just feeling tired. A person with fatigue lacks the motivation to participate in activities and may experience weakness. The fatigue may last for several weeks or months with a mono infection.

A fever indicates that your body is fighting an infection like mono. (Image: Kathleen Finlay/Image Source/GettyImages)

2. Fever

After several days to a week of general illness and fatigue, an individual with mono may develop a fever. The fever can reach 103 degrees Fahrenheit, according to the Merck Manual of Medical Information. The fever is most common in the late afternoon and early evening.

3. Sore Throat

A sore throat typically accompanies the fever and fatigue. Some people may mistake the mono virus for the flu virus based on the initial symptoms. Pus in the back of the throat and swollen tonsils may accompany the pain.

A physician may prescribe antibiotics based on these symptoms, but the sore throat will not clear up with medication. A sore throat may last for several weeks with the virus.

Other Possible Mono Symptoms

Though fatigue, fever and sore throat are the most common first symptoms of mono, there are a few other symptoms that may accompany them.

1. Swollen Lymph Nodes

Lymph nodes, small masses of lymphatic tissue, help signify an infection in the body. Thus, the lymph nodes in the neck or underarms may swell and become painful during a mono infection.

Although the neck lymph nodes swell most often with a mononucleosis infection, any lymph node in the body may swell during the course of the virus. For some individuals, swollen lymph nodes in the body are the only symptom of mono. Swollen lymph nodes may last for a few weeks or longer.

2. Enlarged Spleen

About 50 percent of individuals infected with mononucleosis experience an enlarged spleen, according to the Cleveland Clinic. The function of the spleen is to destroy old red blood cells, trap white blood cells and store extra blood for the body.

The spleen, located under the left side of the ribcage, has a greater chance of rupture once enlarged. An enlarged spleen may cause tenderness when pressed, or it may not cause any symptoms.

3. Muscle Aches or Weakness

Roughly four to seven weeks after you're exposed to mono, you may experience widespread aches in your muscles or generalized weakness throughout your body. This may feel similar to what you experience the day after a rigorous workout. Muscles may be tender to the touch, and the soreness can make your daily activities more difficult.

Googling your symptoms can help, but you should still see your doctor. (Image: PeopleImages/E+/GettyImages)

Frequently Asked Questions About Mono

It's easy to become confused about this illness. Check out the section below for more information on common questions about mononucleosis.

How Do You Get Mono?

Despite its nickname, kissing someone with the illness isn't the only way to contract it. Mono is spread through bodily fluids like saliva and semen. Coughing, sneezing or sharing utensils with an infected individual can cause you to be exposed to the disease. Less commonly, mono can also be spread through sexual contact or blood transfusion.

Is Mono Contagious?

Yes! Mono and the underlying Epstein-Barr virus are very contagious. Because it's so easily spread, upwards of 85 to 90 percent of adults in the United States are exposed to the disease by the time they turn 40.

How Long Is Mono Contagious?

While most people who contract the disease don't begin to feel symptoms for weeks, mononucleosis is contagious from the moment you are exposed. Even if you have the virus and never experience any symptoms, you're still able to pass mono on to others around you. This risk of infection lasts for up to 18 months after the virus is contracted.

How Long Does Mono Last?

The majority of people who get sick with mono see their symptoms resolve within two to four weeks. However, in more severe cases, mono-related fatigue can persist for weeks and even several months after you first become ill.

Can You Get Mono Twice?

In most cases, mono is a one-time experience. However, once you're infected with the Epstein-Barr virus, your body carries it in a dormant state for the rest of your life.

In rare cases, the virus can reactivate and mono can reoccur several months or years later. This is typically seen in people with weaker or compromised immune systems.

What Do YOU Think?

Have you ever had mono? What symptoms did you experience? How long did your symptoms last? Share your thoughts, experiences and questions in the comments below!

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