Mono (infectious mononucleosis) is a contagious viral illness, most often caused by the Epstein-Barr virus (EBV). It spreads through saliva, which is why people call it the kissing disease.
The main symptoms of mono are extreme tiredness, fever, sore throat, swollen glands in the neck and armpits, headache and body aches. Some people also get a rash. Symptoms usually start 4 to 6 weeks after infection, and most people feel better within 2 to 4 weeks. The tiredness can last longer.
By Lynn Pura, RN, MSN, FNP-C, Family Nurse Practitioner at Telemedicine Alaska · Last updated: October 9, 2026
What is mono, and what causes it?
Epstein-Barr virus (EBV) causes most cases of mono. Other infections can cause a similar illness, including cytomegalovirus (CMV), adenovirus, rubella, HIV and hepatitis A, B or C, according to the CDC.
EBV is everywhere. About 9 in 10 adults carry antibodies that show a current or past infection (CDC). Most people catch it as children, and young kids usually have mild or no symptoms, so the infection goes unnoticed.
Teens and young adults tend to get the full illness. The CDC says at least 1 in 4 teens and young adults infected with EBV develop mono, and college students are a common group.
How does mono spread?
Mono spreads through saliva. Kissing is the usual route, and sharing a drink, a fork or a toothbrush can pass it on too. The virus can also spread through blood and semen, during sexual contact, blood transfusions and organ transplants.
Mono is less contagious than a common cold, according to Mayo Clinic. It takes close contact with saliva.
Symptoms appear 4 to 6 weeks after infection, so most people can’t say who they caught it from. The CDC also notes that people can spread EBV for weeks before symptoms show. The practical steps are simple: don’t share cups, utensils or toothbrushes with someone who’s sick, and wash your hands often.
What are the symptoms of mono?
The symptoms of mono are extreme fatigue, fever, sore throat, headache and body aches, swollen lymph nodes in the neck and armpits, and a rash. Less often, the spleen or liver swells.
They don’t all show up at once. The CDC says symptoms can develop slowly.
- Extreme fatigue: the symptom that lasts longest
- Fever
- Sore throat, sometimes with swollen tonsils
- Swollen lymph nodes in the neck and armpits
- Headache and body aches
- Skin rash
- Swollen spleen or liver (less common)
How long do mono symptoms last?
Most people recover in 2 to 4 weeks. Fatigue can last several weeks longer, and in rare cases symptoms stay for 6 months or longer.
| Stage | Timing | What happens |
| Incubation | 4 to 6 weeks after infection | Little or nothing, then symptoms build slowly |
| Peak illness | First 1 to 2 weeks | Fever and sore throat are strongest, then start to ease |
| Recovery | 2 to 4 weeks for most people | Fever and throat pain are gone, energy returns slowly |
| Lingering effects | Several more weeks | Fatigue, swollen glands, enlarged spleen |
| Rare cases | 6 months or longer | Symptoms stay (CDC) |
For some people, fatigue ends before the spleen settles. The CDC says the liver or spleen can stay enlarged after the tiredness is gone. That matters for sports (more on that below).
How can I tell mono from strep throat or the flu?
Mono comes on slowly, and its sore throat doesn’t clear up with antibiotics. Mayo Clinic notes that mono is sometimes misdiagnosed as strep throat for this reason. Strep is bacterial, so antibiotics treat it. Mono is viral, so they don’t. Flu usually hits suddenly.
Example: you’ve had a sore throat for 10 days. Your neck glands are swollen, you’re sleeping 10 hours a night and still tired, and the antibiotics from your first visit changed nothing. That pattern points toward mono and is worth getting checked.
Other viral infections cause fever, sore throat and a rash too. Our article on enterovirus 71 in adults covers one of them. A provider sorts these out by your symptoms, timeline and exposure history.
How is mono diagnosed?
Providers usually diagnose mono from your symptoms and an exam. The CDC says lab tests aren’t usually needed unless the case is atypical.
When blood work is done for EBV mono, it can show:
- More white blood cells than normal
- Unusual looking white blood cells
- Fewer platelets or neutrophils than normal
- Abnormal liver function
A provider will ask how long you’ve been sick, who you’ve been in close contact with, and which medicines you’ve taken. That last question matters, because some antibiotics are a problem with mono (see the next section).
How is mono treated, and how do I recover?
No medicine cures mono. Treatment is rest, fluids and over-the-counter pain and fever relief while your body clears the infection. Antibiotics don’t work on viruses.
- Rest as much as you need.
- Drink plenty of fluids to stay hydrated.
- Take over-the-counter medicine for pain and fever. Ask a provider which one is right for a child.
- Skip contact sports until a provider says you’ve fully recovered.
The sports rule has a reason. Mono can enlarge the spleen, and a hard hit or strain can rupture it, according to the CDC.
The CDC also says people with mono should not take penicillin antibiotics such as ampicillin or amoxicillin. If you were given one for a sore throat before mono came up, ask your provider before taking more.
What are the complications, and when is mono an emergency?
Most people recover with no long-term effects. The serious risk is a ruptured spleen. Sudden, sharp pain in the upper left abdomen needs emergency care right away, and surgery may be needed (Mayo Clinic).
Other complications are less common:
- Liver: mild inflammation (hepatitis), and sometimes yellow skin and eyes (jaundice)
- Tonsils: swelling that can block breathing
- Blood: anemia and a low platelet count
- Heart and nervous system: inflamed heart muscle, meningitis, encephalitis and Guillain-Barre syndrome
People with weakened immune systems, such as those with HIV/AIDS or those taking anti-rejection drugs after an organ transplant, can get much sicker from EBV.
Go to an emergency room or call 911 for sudden sharp pain in the upper left abdomen or trouble breathing. Tell a provider the same day if your skin or eyes turn yellow. A virtual visit is not the right place for any of these.
Can I get care for mono symptoms through telemedicine in Alaska?
Telemedicine works as a first step. A provider reviews your symptoms, medical history, allergies and medications by video, then tells you whether you need in-person tests.
At Telemedicine Alaska, visits are with Lynn Pura, RN, MSN, FNP-C, a Family Nurse Practitioner licensed in Alaska. The visit costs a flat $60. A family consultation for immediate blood relatives, such as a parent and a teen, costs $100 under one appointment. Same-day slots are often open, you don’t need insurance, and prescriptions go to a pharmacy in Alaska when they’re appropriate.
Some problems can’t be handled by video. If your visit isn’t suitable for telemedicine, you’re referred to in-person care and the fee is refunded in full.
Living in the state’s largest city? See our page on telemedicine in Anchorage. Curious how virtual care works for other infections? Read telehealth for sinus infections.
If you think you have mono, book a virtual visit or call (907) 630-0574.
