Azithromycin interacts with a defined set of drug classes, and is contraindicated in macrolide hypersensitivity and existing QT prolongation. Screening for these before the first dose prevents almost all serious events.
Interaction classes to screen
| Class | Concern | Action |
|---|---|---|
| Metabolic inhibitors | Raised plasma levels and exaggerated effect | Reduce dose or space administration |
| Metabolic inducers | Reduced exposure and treatment failure | Review response and adjust |
| Same-target agents | Additive pharmacology | Avoid duplicate therapy |
| Agents affecting the same organ system | GI upset, QT prolongation, transient LFT rise | Monitor and document |
Key takeaways
- Screen every new prescription against the patient's full medicine list.
- Common reactions, GI upset, QT prolongation, transient LFT rise, are amplified by interacting drugs.
- Document the interaction check in the dispensing record.
- Re-screen whenever another long-term medicine is added.
Monitoring in practice
Most interaction risk is manageable with a scheduled review after the onset window of clinical response in 48–72 hours and one further check at steady state. Patients on multiple chronic medicines benefit from an annual structured medication review.
Azithromycin at a glance
| Attribute | Detail |
|---|---|
| Drug class | macrolide antibiotic |
| Common brand | Zithromax |
| Licensed use | respiratory, skin and selected STI infections |
| Available strengths | 250 mg, 500 mg |
| Dosage form | film-coated tablet |
| Typical onset | clinical response in 48–72 hours |
| Duration / dosing interval | long tissue half-life, once-daily short course |
| Storage | below 30 °C |
