Macrolide antibiotic
Azithromycin
Brand names: Zithromax
Adult dose
Dose: 500mg OD ×3 days; STI: 1g single dose; CF prophylaxis: 250–500mg 3× weekly
Route: Oral / IV
Frequency: OD
Clinical pearls
- MHRA Drug Safety Update: cardiac risk in those with QT prolongation / electrolyte disturbance
- BTS pneumonia, BASHH chlamydia/gonorrhoea, NICE CKS, CF Trust prophylactic use
- UKHSA stewardship — preserve
Contraindications
- Severe hepatic impairment
- Hypersensitivity to macrolides
- Concurrent ergot alkaloids
Side effects
- GI upset
- QT prolongation / torsades (less than erythromycin/clarithromycin but significant — MHRA)
- Hepatotoxicity
- C. difficile
- Hearing loss (high-dose, prolonged)
- Cardiac arrhythmia
Interactions
- Warfarin (potentiation)
- Digoxin
- QT-prolonging drugs
- Statins (less than other macrolides)
- Antacids (separate by 2h)
Monitoring
- LFTs
- ECG (QT) if risk factors
- Hearing if long-term
- C. diff
Reference: BNF; NICE CKS; BTS pneumonia; BASHH; CF Trust; MHRA Drug Safety Update; https://bnf.nice.org.uk/drugs/azithromycin/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators
- Centor / McIsaac Score for Strep Pharyngitis · Throat
- FeverPAIN Score for Strep Throat · Throat
- Jarisch-Herxheimer Reaction Severity Assessment · Treatment Reactions
- PID Severity (CDC Diagnostic Criteria) · Gynaecological Infections
- Gustilo-Anderson Classification (Open Fractures) · Fracture Classification
- DRIP Score for Drug-Resistant Pneumonia · Pneumonia
Drugs
Pathways
- Infective Endocarditis · ESC 2023 Infective Endocarditis Guidelines; NICE NG41
- Eczema Herpeticum · BAD; NICE CKS
- Suspected Bacterial Meningitis (Adult) · NICE NG240 (2024); NICE NG143 (paeds)
- Clostridioides difficile Colitis · NICE NG199 (2021); IDSA/SHEA 2021
- Returning Traveller — Fever · NaTHNaC; PHE; ESCMID 2018
- Malaria — Diagnosis & Management · PHE 2016; WHO 2023