Overview
Strep throat is a bacterial throat infection caused by Group A Streptococcus (Streptococcus pyogenes). It causes a sore throat, fever, and swollen lymph nodes, usually without the cough, runny nose, and other cold symptoms. It is important to distinguish from viral sore throat because antibiotic treatment prevents rare but serious complications including rheumatic fever.
How common is it?
Strep throat accounts for 5 to 15% of sore throats in adults and 20 to 30% in children. It is most common in school-age children aged 5 to 15 and in winter and early spring.
Causes and risk factors
Group A Streptococcus spreads through respiratory droplets from infected people or contact with contaminated surfaces.
Common risk factors
- Close contact with an infected person
- School-age children (highest risk age group)
- Winter and spring season
- Crowded environments such as schools and nurseries
- Weakened immune system
Symptoms
- Sudden severe sore throat
- High fever (above 38°C)
- Difficulty swallowing
- Swollen, tender lymph nodes in the neck
- Red, swollen tonsils, sometimes with white patches or streaks of pus
- Absence of cough (important: cough suggests viral cause)
- Petechiae (small red spots) on the soft palate
- Scarlet fever: sandpaper-like rash if a toxin-producing strain
When to see a doctor
See a GP for severe throat pain with high fever, inability to swallow, drooling, or neck swelling, which may suggest peritonsillar abscess. Seek same-day assessment for suspected scarlet fever (requires antibiotics urgently, particularly in children).
Diagnosis
Clinical assessment using FeverPAIN (2 points or more) or Centor criteria guides antibiotic use. Throat swab for Group A Streptococcus culture or rapid antigen test. Blood tests if complications such as peritonsillar abscess are suspected.
Treatments
Phenoxymethylpenicillin (penicillin V)
10-day course of oral penicillin is the antibiotic of choice. Amoxicillin is acceptable (avoid in anyone with possible EBV/glandular fever as it causes a rash). Erythromycin or clarithromycin for penicillin allergy.
Symptomatic relief
Paracetamol or ibuprofen for fever and throat pain. Cold fluids and ice cream may soothe the throat. Aspirin-containing gargles should be avoided in children.
Tonsillectomy
Considered for recurrent tonsillitis (7 or more episodes in 1 year, 5 in 2 years, or 3 in 3 years meeting Scottish Intercollegiate Guidelines criteria). Significantly reduces throat infections for 2 to 3 years post-surgery.
Self-care and lifestyle
- Complete the full course of antibiotics even when feeling better
- Stay home from school or work for at least 24 hours after starting antibiotics
- Wash hands regularly
- Do not share utensils or drinks
Prevention
Good hand hygiene reduces spread. No vaccine is currently available for Group A Streptococcus in the UK, though development is underway.