Emergency signsTake the self-evaluation

Strep vs Mono: How to Tell the Difference

Strep throat and mononucleosis (mono) can look alike. Both can cause a painful sore throat, fever, swollen tonsils and swollen glands in the neck. But they have different causes, they are diagnosed with different tests, and they are treated differently. Mono is a viral illness, so antibiotics don’t help it, and some antibiotics can cause a rash in people who have mono.

This page is educational and is not a diagnosis.

Table of Contents

At a glance

Strep throat Mono
Cause Group A Streptococcus bacteria Most often the Epstein-Barr virus (EBV); other viruses can also cause it
Most common in Children 5 through 15 years old Teenagers and young adults, especially college students
How it spreads Droplets from talking, coughing or sneezing; sharing plates, utensils or glasses Mostly saliva; also blood and semen
How it starts Sore throat often starts suddenly May begin slowly with tiredness, headache and a sore throat that slowly gets worse
Tiredness Can feel unwell Extreme fatigue is a hallmark
Tonsils Red and swollen, sometimes with white patches Swollen, often with a whitish-yellow covering
Swollen glands Swollen, tender neck glands Swollen lymph nodes in the neck and armpits
Spleen or liver Not typical Can swell
Rash Not typical (see scarlet fever) Possible; more likely after taking ampicillin or amoxicillin
Tests Rapid strep test; throat culture Diagnosed from symptoms; blood tests such as the monospot test
Treatment Antibiotics, such as penicillin or amoxicillin No antibiotics; care focuses on relieving symptoms
Recovery Symptoms often improve soon after antibiotics start Most people feel better in 2 to 4 weeks; tiredness can last longer

Symptoms that can point to mono

Mono often builds over several days. According to the CDC and MedlinePlus, signs that suggest mono include:

  • Extreme fatigue that stands out more than the sore throat
  • Swollen lymph nodes in the armpits as well as the neck
  • A swollen spleen or liver, which a clinician may find during an exam
  • A rash, especially after taking ampicillin or amoxicillin for a throat infection
  • A long illness: fever usually drops in about 10 days, but tiredness may last weeks and sometimes 2 to 3 months

Strep throat, by contrast, usually starts suddenly with fever, pain when swallowing and red, swollen tonsils, and it is most common in school-age children. See strep throat symptoms.

How doctors tell them apart

Because the symptoms overlap, a healthcare provider may examine the throat, neck and belly and order tests:

If you are being treated for strep and your symptoms don’t get better within 24 to 48 hours of starting antibiotics, contact your provider. Your symptoms could have another cause.

Why the difference matters

  • Antibiotics treat strep, not mono. Mono is caused by a virus. The CDC advises people with mono not to take penicillin antibiotics like ampicillin or amoxicillin, which can cause a rash in people with mono.
  • Mono can affect the spleen. The CDC advises avoiding contact sports until you fully recover from mono, because they may cause the spleen to rupture. Cleveland Clinic advises avoiding contact sports and strenuous exercise while sick and for up to four weeks afterward.
  • Strep needs the full antibiotic course. Taking antibiotics as prescribed treats the infection and helps prevent complications. See antibiotics for strep throat.

When to get medical care

Contact a healthcare provider if you or your child has a sore throat with fever, swollen glands, or extreme tiredness. Get care right away for trouble breathing, trouble swallowing liquids, drooling, severe belly pain (especially on the upper left side), or signs of dehydration. See when strep throat becomes an emergency.

Medical sources

This information is for education only and does not replace advice from a qualified healthcare provider.