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Mono (Mononucleosis): Signs, Symptoms, & Treatment

Introduction and Summary

You may know mononucleosis (mono) as the kissing disease—a moniker that comes from the fact that this infection is primarily spread through saliva, most often contracted by teens and adolescents. Although mono has an association with romantic contact, you can also get it from sharing foods, drinks, and utensils, or if you’re sneezed or coughed on by an infected person.

Mono is a mild yet very common illness caused by a contagious virus—the virus is so widespread that nearly everyone will catch it by the time they reach adulthood, though not everyone infected will contract mono. In fact, infectious mononucleosis is a description of symptoms caused by the virus, not the name of the virus itself.

In this guide, I will cover:

What Is Mono (Mononucleosis)?

Infectious mononucleosis, more commonly called mono, is a contagious disease characterized by a common group of flu-like symptoms usually caused by the Epstein-Barr virus (EBV). It’s typically a mild illness, albeit an uncomfortable one, that lasts two to four weeks, though can last months.

Mononucleosis is most common in young adults. The most recognizable mono symptoms include a sore throat, fever, swollen glands, and fatigue. In many cases, it can be hard to tell mono apart from the flu (influenza), as they share similar symptoms. While there is no direct cure for mono, at-home remedies and medications are used to ease discomfort and pain until the infection has resolved.

What Causes Mono?

Mono is usually caused by the Epstein-Barr virus (EBV), an extremely prevalent virus, although other viruses can also trigger mono symptoms. Up to half of adolescents and adults infected with EBV will get mono, though if you’re infected with EBV, you may not experience any symptoms at all.

Why is mono called “the kissing disease”?

EBV is a contagious virus that spreads through saliva, which has led to mono being dubbed “the kissing disease.” While this is the most common way it is passed between people, you can get mono without kissing someone by sharing food, drinks, and utensils with someone who is infected, or by being coughed or sneezed on by them.

How contagious is mono?

EBV and similar viruses that cause infectious mononucleosis can also be spread through blood, bodily fluids, sexual contact, and organ transplantation. In cases where it is passed through sexual contact, mono can be considered a sexually transmitted disease (STD), although mono is more often spread through contact with saliva.

If you’ve had mono once, it’s unlikely that you’ll get mono again. Once you have been infected with EBV, the virus remains dormant in your body for the rest of your life. Because of this, there is very little chance of catching mono after you’ve had it once. In rare cases, usually associated with a weakened immune system, EBV can reactivate in the body, but even then your symptoms are likely to be mild, if perceptible at all.

Mono Signs and Symptoms

The primary signs of mono in adults and adolescents are sore throat combined with a high fever. Generally, a person suffering from mono will experience discomfort when eating and swallowing, and it may be painful to eat anything other than soft foods.

Other signs of mono include:

  • Swollen lymph glands in the neck and armpits
  • Extreme fatigue
  • Headache
  • Body aches or muscle weakness
  • Swollen tonsils
  • Night sweats
  • A rash which appears as pinkish-red or purple spots on the skin

The symptoms of mono may initially be misdiagnosed as strep throat. In these cases, a person with mono may get an itchy red rash after taking antibiotics (such as ampicillin) that have been prescribed for strep throat. These antibiotics do not help treat infectious mononucleosis.

Mono in children may appear as a mild cold, or the virus may not cause any symptoms. Young children who have contracted EBV will likely be immune to mono in the future. Mono in adults and adolescents generally causes one or more of the above symptoms, although it is possible for adults to contract the virus and be asymptomatic.

How Is Mono Diagnosed?

Because mono shares similar symptoms with multiple infections and viruses, your doctor will consider your age and whether you’ve been in close contact with a large number of people to rule out other illnesses like strep throat, or a more serious virus like hepatitis A.

During an examination, your doctor will take your temperature and check the glands in your neck and armpits for swelling. They may also examine the upper left region of your stomach to check for signs of an enlarged spleen. Your doctor may also order a complete blood count to check for a high lymphocyte count or high white blood cell count, both of which often indicate an infection.

If your physical examination reveals signs of mono, your doctor will order an EBV antibody test to confirm a mono diagnosis.

An EBV antibody test can detect infectious mononucleosis as early as the first week after symptoms appear. This blood test looks for EBV-specific antibodies in your blood and, if detected, can determine whether you have or have had the infection.

Mono Treatment

There’s no cure for infectious mononucleosis. Most treatment options, including medications and home remedies, will instead focus on relieving your symptoms. It’s important to get plenty of rest and drink fluids as your body fights the infection.

To ease discomfort, your doctor may prescribe a corticosteroid to reduce swelling in the throat, tonsils, and glands. Mono treatment can also include over-the-counter (OTC) medications such as acetaminophen to help reduce fever or ease headaches.

To soothe throat pain, try at-home remedies for sore throat, such as:

  • Gargling with warm saltwater
  • Eating warm soup
  • Drinking warm beverages, such as tea with honey or warm water with lemon
  • Sucking on lozenges that soothe or temporarily numb the throat
  • Using sore throat sprays
  • Eating popsicles, ice cream, and other cold, soft foods

In most cases, mono symptoms will resolve within four weeks, although some people continue to experience extreme fatigue for weeks afterwards. In more severe cases, mono can last for six months or longer.

If you are diagnosed with mono, refrain from taking penicillin-based antibiotics. These are used to treat bacterial infections—because mono is a viral infection, antibiotics will not help. If taken while you have mono, antibiotics such as ampicillin or amoxicillin may cause an itchy rash.

Mono Prevention

After contracting mono once, most people typically cannot get it again. An estimated 85-90% of adults have developed EBV antibodies by the time they turn 40.

Mono is contagious, although the exact incubation period is unclear—it may continue to be contagious for up to three months or longer after symptoms are gone. Even after a person has fully recovered from mono, EBV will remain inactive in their bodies forever and will be shed occasionally in the throat, allowing that person to potentially spread the virus to others.

If you have mono, anyone who comes into direct contact with your saliva can become infected. You can help prevent spreading it to others by avoiding close contact with other people, and refraining from kissing or sharing food and beverages with anyone.

Risk Factors and Complications

The two primary risk factors for developing mono are age and interaction with large groups of people. Frequent contact with large groups increases the likelihood of catching EBV, and your age determines the likelihood that you’ll show mono symptoms as a result.

Because adolescents and young adults are most likely to develop mono symptoms, infectious mononucleosis is frequently seen in high school and college students.

You may be at higher risk of developing mono if you:

  • Are between the ages of 15-30
  • Are a student
  • Work in the medical field as a nurse, doctor, intern, or other caregiver
  • Take medications that suppress your immune system

Mono in adults over age 30 is less common, likely because most adults have already contracted the virus, with or without showing any symptoms, and are now immune to it.

Mono is typically not a serious illness, though there are a few complications to be aware of and protect against while you are recovering from the disease.

Infectious mononucleosis can lead to an enlarged spleen, which increases the risk of rupture. If you get mono, do not participate in contact sports or other strenuous activities for at least two weeks after your symptoms have abated to avoid rupturing your spleen.

While your body is fighting infectious mononucleosis, your immune system is compromised, so it may be easier for you to contract a secondary infection, such as strep throat, tonsillitis, or a sinus infection. If you believe you’ve developed another infection while recovering from mono, contact your doctor to determine appropriate treatment.

Rarely, people with severe cases of mono may develop additional complications including:

When to See a Doctor

If you’re experiencing signs of mono, make an appointment with your doctor to get a diagnosis. Once you are diagnosed with mono, you likely won’t need to see your doctor again. The majority of mono symptoms can be treated from home with adequate rest, and your symptoms should begin to ease within two to four weeks.

If you see no improvement in your condition after two weeks, or if your symptoms get worse, contact your doctor. It’s worth checking whether there’s something more serious going on.

If you suddenly experience intense pain in the upper left side of your abdomen, it could be a sign of spleen rupture, and it’s imperative that you go to the hospital or call 911.

How K Health Can Help

Mono is very contagious so if you’re experiencing symptoms you should talk to a doctor to get a diagnosis. Did you know you can get affordable primary care with the K Health app? Download K to check your symptoms, explore conditions and treatments, and if needed text with a doctor in minutes. K Health’s AI-powered app is HIPAA compliant and based on 20 years of clinical data.

Howard Jeffries, MD

A pediatric cardiac intensivist at Seattle Children's Hospital, Dr. Jeffries is also Senior Medical Director, Regional Network. He completed a residency in pediatrics and a fellowship in pediatric intensive care. He has published chapters and peer-reviewed articles, with an emphasis on cardiac intensive care, informatics, outcomes assessment and quality improvement.

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