Centor / McIsaac Score for Strep Pharyngitis
Predicts likelihood of Group A Streptococcal (GAS) pharyngitis to guide antibiotic prescribing. McIsaac modification adds age adjustment.
Score interpretation
Centor/McIsaac 0 or less: GAS pharyngitis very unlikely (< 10%).
→ No antibiotics. Symptomatic treatment: regular analgesia (paracetamol / ibuprofen), adequate fluid intake. No throat swab required routinely.
Score 1–2: Low-moderate probability of GAS (~15–30%). Antibiotics not routinely indicated.
→ Symptomatic treatment. Consider throat swab or RADT (rapid antigen detection test). Delayed prescription strategy: prescribe, advise only to use if not improving after 3 days. Safety net.
Score 3–5: Higher probability of GAS pharyngitis (~40–60%). Antibiotic treatment appropriate.
→ Phenoxymethylpenicillin 500mg QDS × 10 days (first-line). Amoxicillin 500mg TDS × 10 days (alternative — do NOT use if EBV/glandular fever suspected). Allergy: clarithromycin 250mg BD × 5 days. Advise on completing course.
Interpretation bands for the Centor Score. Apply clinical judgement and local guidance.
References
- Centor RM et al. The diagnosis of strep throat in adults in the emergency room. Med Decis Making. 1981.
- McIsaac WJ et al. A clinical score to reduce unnecessary antibiotic use in patients with sore throat. CMAJ. 1998.
- NICE NG84. Sore throat (acute): antimicrobial prescribing. 2018.
Related
Curated clinical cross-links plus same-class fallbacks.
- Phenoxymethylpenicillin (Penicillin V) · Antibiotic — Tonsillitis / Pharyngitis
- Doxycycline 100mg (Acne / Rosacea) · Oral tetracycline antibiotic (anti-acne / anti-rosacea)
- Lymecycline 408mg (Acne) · Oral tetracycline antibiotic (anti-acne)
- Erythromycin 2% Topical · Topical macrolide antibiotic (anti-acne)
- Mupirocin 2% Ointment · Topical antibiotic (pseudomonic acid)
- Fusidic Acid 2% Cream · Topical antibiotic (steroidal antibiotic)
- Adult Upper Airway Obstruction (Stridor) · DAS 2015 unanticipated difficult airway; RCEM
- Epistaxis Management · ENT-UK / NICE
- Acute Otitis Media · NICE NG91 2018
- Tonsillitis and Sore Throat · NICE NG84 2018
- Benign Paroxysmal Positional Vertigo · NICE CG124 / AAO-HNS Guidelines
- Acute Rhinosinusitis · NICE NG79 2017 / EPOS 2020
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.