Azithromycin
Brand names: Zithromax
Azithromycin is a macrolide antibiotic indicated for a range of bacterial infections including respiratory tract, skin and soft-tissue, otitis media and certain sexually transmitted infections, valued for its convenient short courses.
ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.
Clinical monograph
How it works
It inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit and preventing peptide chain elongation, conferring activity against many Gram-positive, atypical and some Gram-negative organisms.
Prescribing in practice
- Because azithromycin can prolong the QT interval, avoid or use with caution in those with known QT prolongation, significant cardiac disease, electrolyte imbalance or other QT-prolonging medicines.
- Rare but serious hepatotoxicity has been reported, and treatment should be stopped if signs of liver injury occur.
- It may interact with drugs such as certain ergot alkaloids and statins, so concomitant therapy should be reviewed.
Monitoring
Routine monitoring is not usually required for short courses, but assess liver function and cardiac risk where clinically indicated.
Counselling the patient
- Finish the full course as prescribed.
- Seek advice if you develop palpitations, fainting or jaundice.
- Let your clinician know about other medicines and any heart conditions.
Evidence & guidelines
Azithromycin is widely used across UK antimicrobial guidance, and the MHRA has issued reminders regarding its potential to prolong the QT interval.
Reference: NICE CKS; BTS pneumonia; BASHH; CF Trust; MHRA Drug Safety Update; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).
Related
Curated clinical cross-links plus same-class fallbacks.
- 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
- 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