Strep vs. Mono and When to Head to the ER

When you’re feeling under the weather with a sore throat, it’s natural to wonder what might be causing it. Two common culprits—strep throat and mononucleosis (commonly called mono)—can have overlapping symptoms, but they’re very different illnesses. Understanding the differences between strep and mono can help you know what steps to take for treatment and when it’s time to seek emergency care.

Strep Throat vs. Mono: Key Symptoms

While both strep and mono can leave you feeling fatigued and unwell, their symptoms and causes vary.

Strep Throat

Strep throat is a bacterial infection caused by Group A Streptococcus. It often appears suddenly and can cause the following symptoms:

• Severe sore throat that may feel worse when swallowing
• Red or swollen tonsils, sometimes with white patches or streaks of pus
• Swollen lymph nodes in the neck
• Fever (usually 101°F or higher)
• Headache or nausea
• Fatigue or weakness

Strep throat is highly contagious and spreads easily through respiratory droplets, such as sneezing or coughing.

Mononucleosis (Mono)

Mono, on the other hand, is a viral illness most commonly caused by the Epstein-Barr virus (EBV). Unlike strep, it develops gradually and lasts much longer. Symptoms of mono include:

• Persistent sore throat (often less sharp than strep)
• Fatigue that can last weeks or even months
• Swollen lymph nodes in the neck, underarms, or groin
• Swollen tonsils, possibly with white or yellow coating
• Fever, typically lower than with strep
• Splenomegaly (enlarged spleen), causing abdominal discomfort in some cases

Mono is also contagious, but it spreads through saliva and close contact, earning it the nickname “the kissing disease.”

How to Differentiate Between Strep and Mono

Since the symptoms overlap, it can be hard to tell them apart without medical testing. Here are a few clues that may help, though a professional diagnosis is always recommended:

• Onset: Strep appears suddenly, while mono progresses slowly.
• Fatigue: Mono tends to cause extreme and prolonged fatigue; strep does not to the same extent.
• Abdominal Pain: Mono can cause discomfort in the left side of the abdomen due to an enlarged spleen, a symptom not seen with strep.

The only way to confirm the diagnosis is through testing. A healthcare provider can perform a rapid strep test, throat culture, or blood test for mono antibodies to determine the exact cause of your symptoms.

When to Seek Emergency Care

Both strep throat and mono can usually be managed with proper treatment, but there are times when either condition may require immediate medical attention.

Signs to Seek Emergency Care for Strep Throat:

• Difficulty breathing or swallowing
• Severe swelling in the neck or throat
• High fever that doesn’t respond to medication
• Dehydration due to difficulty drinking fluids

Signs to Seek Emergency Care for Mononucleosis:

• Severe abdominal pain, especially on the left side (may signal a ruptured spleen)
• Persistent high fever
• Difficulty breathing due to swollen tonsils or lymph nodes
• Unexplained severe fatigue with other worsening symptoms

If you or a loved one experience any of these symptoms, it’s important to head to an ER promptly for evaluation and treatment.

TotalCare Is Here for You

When symptoms strike and you’re unsure whether it’s strep, mono, or something more serious, TotalCare has you covered. Our freestanding ERs and urgent care/family practice clinics are here to provide expert care whenever you need it. With locations throughout the Dallas/Fort Worth Metroplex and over 10,000 5-star patient reviews, TotalCare is proud to be known as the choice ERs of Texas and the choice urgent care/family clinics of Texas. Whether it’s diagnosing and treating strep throat, managing the symptoms of mono, or addressing more serious concerns, our compassionate team is here to support your health. Visit your nearest TotalCare location today—you can trust us to get you back to feeling your best, quickly and safely.