Locations:
Search IconSearch

How To Tell If Your Child Has Mono

Fatigue leads a list of telltale signs of the ‘kissing disease’

Teen tired and sick

Your teen seems sleepier and more tired than usual. (How’s that even possible, right?) They’re also complaining about a sore throat and their neck seems a bit swollen. Plus, their skin seems sort of yellow.

Advertisement

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

The symptoms line up with mononucleosis, or “mono” for short. You may also know the contagious infection by a much cuter name — “the kissing disease” — given the popular way it’s transmitted.

But how can you know for sure if your child has mono? And what do you do next? Pediatrician Heather Sever, DO, has some answers.

What is mono?

For starters, mono is a viral infection. It spreads from person to person through bodily fluids, most often saliva — hence, the “kissing” connection, though it can also be passed along by less romantic means like:

  • Sharing a drink.
  • Eating off the same fork or spoon.
  • Using another person’s toothbrush.
  • Being in someone’s cough or sneeze zone.

The virus behind the vast majority of mono cases is Epstein-Barr virus (EBV), a type of herpes virus. Don’t be alarmed by that family tree: EBV is vastly different from the herpes simplex virus that causes genital and oral herpes.

Also, EBV is extremely common. Around 90% of Americans are infected with it by the age of 35. Many just carry the virus, says Dr. Sever. Not everyone who has it develops mono symptoms.

For those who do show symptoms … well, you’re probably looking at a month or two to fully recover, says Dr. Sever. It’s also possible in some cases that fatigue may linger for longer than six months.

Advertisement

Common symptoms of mono

Mono typically announces its presence slowly, with symptoms coming on gradually. It can take four to eight weeks for signs of the illness to show after exposure. Some cases may be mild. Others may be severe.

So, what should you look for regarding symptoms? Common signs include:

  • Fatigue.
  • Fever.
  • Sore throat (possibly with white spots or pus on tonsils).
  • Headaches.
  • Enlarged lymph nodes in your neck, armpits or groin.
  • Muscle aches or weakness.

People with mono may also develop a mild liver inflammation, or hepatitis. Liver issues may lead to jaundice, a yellowing of your skin and whites of your eyes, notes Sever.

A rash may also occasionally be seen, often coinciding with antibiotic use. Nausea and vomiting may be part of the package, too.

What about abdominal pain?

A case of mono also could lead to pain in the upper left side of your abdomen behind your ribs. That’s your spleen expressing its displeasure. Don’t ignore it.

The pain may be a sign of splenomegaly, or an enlargement of your spleen, and could lead to a splenic rupture. “This is a life-threatening condition because it can lead to significant blood loss,” explains Dr. Sever.

About 50% to 60% of mono cases include an enlarged spleen, says Dr. Sever.

This complication is especially notable for athletes, who’re at increased risk of a rupture with physical activity. As a precaution following the start of symptoms, that means no participation in non-contact sports for three weeks.

Make it four weeks of downtime for contact sports, including football, basketball, baseball/softball, hockey, volleyball, gymnastics, lacrosse and wrestling.

Take four weeks off from weightlifting, too, given the pressure it puts on your abdomen.

How is mono diagnosed?

A heterophile blood test (monospot) will indicate if all of the feeling-icky symptoms point to mono. An additional test called a complete blood count (CBC) will show if there’s an increased white blood cell count and atypical lymphocytes, an unusual-looking white blood cell.

A word of warning, though: “There is a high false-negative rate for the monospot test in the first week of the illness — up to 25%,” notes Dr. Sever. “People who exhibit all of the symptoms but have a negative test may have to have it repeated later or have a specific EBV test done.”

It should also be noted that testing doesn’t open the door to a magical cure-all or antibiotic. “There is no specific treatment for mononucleosis other than an abundance of rest,” says Dr. Sever.

So why get an official diagnosis? It helps explain the worrisome symptoms (especially fatigue) and rule out other illnesses such as a streptococcal infection. Confirmation of mono also helps minimize risks when it comes to doing activities.

Advertisement

At what age do people typically get mono?

The peak period for mono covers the late teen years and early adulthood — basically, the span between age 15 and 24, says Dr. Sever.

Younger kids are also prone to picking up EBV but often don’t show symptoms of mono. “There is a high false-negative rate in infants and children under the age of 4,” adds Dr. Sever. “They may have very mild symptoms and are often undiagnosed.”

What to do if your child has mono

Rest is best when it comes to dealing with mono. Pain relievers such as acetaminophen or ibuprofen can be used as needed, says Dr. Sever. Make sure to get in enough fluids and food, too.

There aren’t any restrictions or specific quarantine guidelines concerning returning to work or school. “It is largely dependent on the severity of symptoms and degree of fatigue experienced,” says Dr. Sever.

Preventive measures are helpful in limiting the spread of mono, though. Wash your hands frequently and don’t share food, drinks, utensils or toothbrushes with an infected individual. It’s a good idea to hold off on kisses, too.

Advertisement

Learn more about our editorial process.

Related Articles

Person bleeding from a cat scratch on arm, with cat playing on cat tree in livinng room
March 3, 2025/Infectious Disease
Should You Worry About a Cat Bite or Scratch?

The risk of infection makes fast and thorough treatment critical

Laughing, happy baby being carried by caregiver in airport
February 14, 2025/Children's Health
Flying With a Baby: Your Questions Answered

Dress baby in layers, gate-check your stroller and bring noise-canceling headphones

Caregiver sleeping on bed, with baby sleeping in crib in the same room
February 13, 2025/Children's Health
Co-Sleeping With Your Baby: How To Be Safe

Experts recommend having infants sleep in your bedroom but not in your bed

Caregiver laughing and reading to two happy kids on couch
February 12, 2025/Parenting
4 Signs Your Child Is Ready To Stop Napping

Preschoolers who wake up early or have trouble falling asleep may not need their afternoon nap

Caregiver standing with suitcase nearby, hugging child, with another caregiver sitting on couch
February 7, 2025/Parenting
Why Parallel Parenting May Be Needed in High-Conflict Scenarios

If parents can’t get along with one another, they’ll need to determine what’s best for their child in separate situations

Teenager sitting on exam table talking to healthcare provider
February 6, 2025/Heart Health
What Causes Heart Attacks in Young People?

Congenital heart disease, genetic conditions and unhealthy lifestyle habits can put teens at higher risk for heart attack

Caregiver with child on their lap, sitting across from healthcare provider, talking
February 6, 2025/Brain & Nervous System
Plexiform Neurofibromas: Here’s What You Should Ask Your Child’s Doctor

These rare tumors are almost always a side effect of a condition called neurofibromatosis type 1, so asking if this is the case is important

Physical therapist helping person with walking in therapy gym
February 4, 2025/Brain & Nervous System
What To Know About Managing Plexiform Neurofibroma Symptoms

Staying active and documenting symptoms can help you, and your care team, stay on top of this chronic condition

Trending Topics

Person in bed sleeping on their side, covers off
Breathing Problems? Try These Sleep Positions

If you’re feeling short of breath, sleep can be tough — propping yourself up or sleeping on your side may help

A couple looking at skyline, with one person slightly behind the other, head bent down
What Is Anxious Attachment Style — and Do You Have It?

If you fear the unknown or find yourself needing reassurance often, you may identify with this attachment style

Glasses and bottle of yellow-colored prebiotic soda, with mint, lemon and ginger garnish
Are Prebiotic Sodas Good for You?

If you’re looking to boost your gut health, it’s better to get fiber from whole foods

Ad