At a glance
- Mono spreads mainly through saliva: kissing and sharing drinks, utensils or toothbrushes.
- Symptoms appear 4 to 6 weeks after infection and are most common in teens and young adults.
- Most feel better in 2 to 4 weeks, but tiredness can last for several weeks or months.
- Antibiotics do not help; amoxicillin and ampicillin should not be used and can cause a rash.
- No contact sports or rough play until the doctor confirms full recovery and a normal-size spleen.
- Call 911 for trouble breathing or swallowing, or sudden, sharp, severe belly pain.
Mono symptoms in children and teens
Teens usually have a sore throat, fever, swollen glands in the neck and deep tiredness. The throat may have white patches on the tonsils.
Headache, body aches, a poor appetite, puffy eyelids and a rash can also occur.
- Glands in the armpits or groin can swell, and the liver and spleen can get bigger.
- Babies and young children who catch the virus often have no symptoms or only a mild, short illness.
- Doctors diagnose mono from the exam, sometimes with blood tests such as a blood count or EBV antibody test.
How mono usually runs
- 4–6 weeks after infectionSore throat, fever, swollen glands and tiredness begin.
- About 10 daysFever usually settles; call if symptoms are not easing.
- 2–4 weeksMost children feel better; glands and spleen shrink back. No contact sports until cleared.
- 2–3 monthsTiredness may linger; a few teens take 6 months or longer to recover.
Warning signs: when to get help
- Call 911 or your local emergency number for trouble breathing or swallowing, or for sudden, sharp, severe belly pain.
- Sudden belly pain, especially with fainting, can mean the spleen has torn, which is rare but an emergency.
- Call the doctor for any belly pain, a very sore throat or swollen tonsils.
- Call if your child is drinking too little to stay hydrated.
- Call if symptoms last longer than 10 days or keep getting worse.
Mono: when to get help
- Call 911 nowTrouble breathing or swallowing, sudden sharp belly pain, or fainting.
- Call the doctor todayAny belly pain, very large tonsils, a severe sore throat, or drinking too little.
- Book a visitSymptoms beyond 10 days, or getting worse instead of better.
- Care at homeDrinking, swallowing and breathing well: rest, fluids, pain medicine, no contact sports.
Treatment and home care
- There is no cure for the virus; rest and plenty of fluids help the body recover.
- Give acetaminophen or ibuprofen for pain and fever, at the dose for your child's age and weight.
- Older children can gargle with warm salt water to soothe the throat.
- Antibiotics do not treat mono, and amoxicillin or ampicillin can bring out a pink, measles-like rash.
- Steroid medicine is kept for a few children with problems such as tonsils swollen enough to narrow the airway.
- Plan a gradual return to school and activities as energy allows.
Sports, the spleen and when it is safe to play
Mono can make the spleen swell, and a swollen spleen can tear during contact or a hard fall.
- CDC advises avoiding contact sports until full recovery, and the AAP says to wait until the spleen is no longer swollen.
- These sources give no fixed number of weeks, so the doctor decides when your child is cleared.
- Until then, skip contact sports such as football, hockey and wrestling, and rough play.
How mono spreads
- Epstein-Barr virus passes mainly in saliva, so do not share drinks, food, utensils or toothbrushes, and avoid kissing while ill.
- The virus stays in the body for life and can be passed on again later, even without symptoms.
- Most people catch it at some point, often in childhood; about 9 in 10 adults show signs of past infection.
- There is no vaccine against mono.
Common questions
How long does mono last in kids and teens?
The worst of it usually passes within a month. Fatigue is what lingers, sometimes for a couple of months or more.
When can my teen play sports after mono?
Only after the doctor gives the all-clear. The spleen has to be back to normal size, and feeling well is not proof of that.
Is mono contagious, and for how long?
Yes, through saliva. The virus never fully leaves the body, so there is no clear end to spreading it; not sharing cups or kissing during the illness lowers the risk.
Why did my child get a rash after amoxicillin for a sore throat?
Mono itself makes this rash more likely when these antibiotics are taken. Tell the doctor, who can check for mono and decide what it means for future antibiotics.
Can young children get mono?
They can catch the virus, but at that age it often passes unnoticed or looks like an ordinary cold. Classic mono is mostly a teen and young-adult illness.
Sources
- CDC — About Infectious Mononucleosis (Mono)
- CDC — About Epstein-Barr Virus (EBV)
- AAP — Mononucleosis
- NIH MedlinePlus — Mononucleosis
Written for Pedemy in our own words from the sources above; checked October 2026. For education only, not medical advice. Pedemy is independent and not affiliated with or endorsed by the organizations cited.