Infection of the Throat (Pharyngitis)

What is Infection of the Throat (Pharyngitis)?

Pharyngitis, commonly called a sore throat, is inflammation of the pharynx—the part of the throat that lies behind the mouth and nasal cavity and above the larynx (voice box). The inflammation can be caused by an infection (viral or bacterial), irritants, or systemic illnesses. When the lining of the pharynx becomes red, swollen, and painful, patients typically describe the sensation as a “sore throat.” While most cases are mild and resolve on their own, some can progress to more serious conditions such as peritonsillar abscess, rheumatic fever, or streptococcal sepsis.

Understanding the underlying cause is essential because treatment differs dramatically between viral and bacterial pharyngitis. For example, antibiotics are lifesaving for bacterial infections like Streptococcus pyogenes (group A strep) but provide no benefit for viral illnesses and may contribute to antibiotic resistance.

Sources: Mayo Clinic; Centers for Disease Control and Prevention (CDC); National Institutes of Health (NIH).

Common Causes

Pharyngitis has many triggers. Below are the most frequent culprits, grouped by type.

• Viral infections (70‑90% of cases)
  • Rhinovirus (common cold)
  • Influenza A & B
  • Coronavirus (including SARS‑CoV‑2)
  • Epstein‑Barr virus (causes infectious mononucleosis)
  • Parainfluenza viruses
  • Adenovirus
  • Enteroviruses (e.g., coxsackievirus)
• Bacterial infections
  • Group A Streptococcus (Streptococcus pyogenes)
  • Neisseria gonorrhoeae (rare, sexually transmitted)
  • Corynebacterium diphtheriae (diphtheria)
  • Mycoplasma pneumoniae
  • Chlamydia pneumoniae
• Fungal infections (usually in immunocompromised patients)
  • Candida species (thrush)
• Irritants & environmental factors
  • Allergens (pollen, dust mites)
  • Tobacco smoke or vaping vapors
  • Dry indoor air
  • Chemical fumes (e.g., cleaning products)
• Systemic conditions
  • Acid reflux (Laryngopharyngeal reflux)
  • Autoimmune diseases (e.g., rheumatoid arthritis, Sjögren’s syndrome)

Associated Symptoms

While the primary complaint is throat pain, pharyngitis often presents with a constellation of other signs that can help pinpoint the cause.

• Fever (often higher with bacterial infection)
• Swollen, tender lymph nodes in the neck
• Redness and white exudates on the tonsils or posterior pharynx
• Hoarseness or loss of voice
• Difficulty swallowing (odynophagia) or pain with swallowing (dysphagia)
• Headache or ear pain (referred pain)
• Cough, runny nose, or sneezing (more common in viral infections)
• Fatigue, muscle aches, and malaise
• Swollen tonsils or “white patches” (common with strep and mononucleosis)
• Rash (scarlet fever rash with strep, maculopapular rash with certain viruses)

When to See a Doctor

Most sore throats improve within a few days with self‑care. However, medical evaluation is warranted when any of the following appear:

• Fever ≥ 102 °F (38.9 °C) lasting more than 48 hours
• Severe throat pain that makes swallowing liquids impossible
• Visible white patches or pus on the tonsils
• Neck swelling or very tender lymph nodes
• Rash, especially a sandpaper‑like rash on the trunk
• Recent exposure to someone with confirmed strep throat or infectious mononucleosis
• Persistent symptoms (> 7 days) without improvement
• History of recent antibiotic use without relief (possible resistant bacteria)
• Difficulty breathing, drooling, or a muffled voice (possible peritonsillar abscess)

Children, pregnant women, the elderly, and people with chronic health conditions (e.g., diabetes, heart disease) should seek evaluation sooner, as they are at higher risk for complications.

Diagnosis

Accurate diagnosis combines a careful history, physical examination, and selective testing.

History & Physical Exam

• Onset, duration, and severity of throat pain
• Associated symptoms (fever, cough, rash, recent sick contacts)
• Vaccination status (particularly diphtheria and COVID‑19)
• Risk factors (smoking, immunosuppression, recent travel)
• Examination of the pharynx, tonsils, and uvula for redness, exudate, or ulceration
• Palpation of cervical lymph nodes

Rapid Antigen & Molecular Tests

• Rapid Streptococcal Antigen Test (RST) – Gives results in 5‑10 minutes; highly specific but less sensitive than culture.
• Rapid Influenza Diagnostic Test (RIDT) – Helpful during flu season.
• Polymerase Chain Reaction (PCR) panels – Detect multiple respiratory viruses (including SARS‑CoV‑2) from a throat swab.

Throat Culture

Gold standard for confirming group A strep. Swab the tonsillar area and culture on blood agar; results are available in 24‑48 hours. Recommended when rapid test is negative but clinical suspicion remains high.

Blood Tests

• Complete blood count (CBC) – Elevated white blood cells suggest bacterial infection; atypical lymphocytes point toward mononucleosis.
• Monospot or EBV serology – For suspected infectious mononucleosis.
• Anti‑streptolysin O (ASO) titers – May be used retrospectively to confirm recent strep infection.

Imaging (Rare)

Neck ultrasound or contrast‑enhanced CT is reserved for complications such as peritonsillar abscess or deep neck space infection.

Treatment Options

Treatment is directed at the underlying cause and symptom relief. Below, options are divided into medical (prescription) and home‑care measures.

Medical Treatments

• Antibiotics – Indicated for confirmed bacterial infections.
  • Group A strep: Penicillin V or amoxicillin (first‑line). For penicillin‑allergic patients, a macrolide (e.g., azithromycin) is used.
  • Diphtheria: Erythromycin or penicillin G plus antitoxin.
  • Gonococcal pharyngitis: Ceftriaxone IM + azithromycin.
• Antiviral agents – Reserved for specific viral causes.
  • Influenza: Oseltamivir or baloxavir within 48 hours of symptom onset.
  • Herpes simplex virus: Acyclovir or valacyclovir for severe ulcerative lesions.
• Corticosteroids – Short courses (e.g., dexamethasone 0.6 mg IM) may reduce pain and swelling in severe bacterial pharyngitis, especially in children.
• Analgesics – Acetaminophen or ibuprofen for fever and pain relief.

Home Care & Symptomatic Relief

• Stay hydrated – warm broths, herbal teas, and water keep the throat moist.
• Salt‑water gargle – ½ teaspoon of non‑iodized salt dissolved in 8 oz of warm water, 3–4 times daily.
• Honey (adults & children > 1 year) – 1‑2 teaspoons can soothe irritation and has mild antimicrobial properties.
• Humidify indoor air – Use a cool‑mist humidifier, especially in dry winter months.
• Avoid irritants – Smoke, strong fragrances, and acidic foods (citrus, tomato) can worsen pain.
• Over‑the‑counter lozenges or throat sprays containing benzocaine or menthol for short‑term numbing.
• Rest – Adequate sleep supports the immune system.

Prevention Tips

Many cases of pharyngitis are contagious, so simple hygiene and lifestyle measures can dramatically reduce risk.

• Practice frequent hand washing with soap for at least 20 seconds, especially after being in public places.
• Avoid close contact (kissing, sharing utensils, cups) with anyone who has a sore throat.
• Cover mouth and nose with a tissue or elbow when coughing or sneezing; dispose of tissues promptly.
• Stay up to date on vaccinations: flu shot annually, COVID‑19 boosters, DTaP (diphtheria, tetanus, pertussis), and MMR (measles‑mumps‑rubella).
• Maintain good oral hygiene – brushing twice daily and flossing reduces bacterial load.
• Drink plenty of fluids and keep the throat moist; dry mucosa is more vulnerable to infection.
• Limit exposure to tobacco smoke and vaping aerosols.
• For children, encourage proper hand hygiene at school and limit attendance when ill.

Emergency Warning Signs

Key Take‑aways

Pharyngitis is a common but often self‑limited condition. Recognizing whether the cause is viral or bacterial is crucial because it determines the need for antibiotics and the risk of complications. Most sore throats can be managed with supportive care, but prompt medical evaluation is necessary for high fevers, persistent symptoms, or any signs of airway compromise. Practicing good hygiene, staying vaccinated, and avoiding irritants can substantially lower the chance of infection.

References

• Mayo Clinic. “Sore throat.” Accessed April 2024. https://www.mayoclinic.org/diseases-conditions/sore-throat
• CDC. “Strep Throat – Group A Streptococcal (GAS) Disease.” Updated 2023. https://www.cdc.gov/groupastrep/diseases-public/strep-throat.html
• NIH National Institute of Allergy and Infectious Diseases. “Pharyngitis.” 2022. https://www.niaid.nih.gov/diseases-conditions/pharyngitis
• World Health Organization. “Diphtheria.” 2023. https://www.who.int/news-room/fact-sheets/detail/diphtheria
• Cleveland Clinic. “When to See a Doctor for a Sore Throat.” 2024. https://my.clevelandclinic.org/health/diseases/21184-sore-throat