Azithromycin 1 Gram Single Dose: Primary Indications
A single 1-gram oral dose of azithromycin is FDA-approved and guideline-recommended for treating uncomplicated genital chlamydial infections (urethritis and cervicitis) and chancroid in adults. 1
FDA-Approved Indications for 1g Single Dose
The FDA label explicitly lists two indications for azithromycin 1g single dose in adults: 1
- Non-gonococcal urethritis and cervicitis (caused by Chlamydia trachomatis)
- Genital ulcer disease (chancroid) (caused by Haemophilus ducreyi)
Chlamydial Infection Treatment
Azithromycin 1g orally as a single dose achieves 97-98% cure rates for uncomplicated genital chlamydial infections, making it equally effective to doxycycline 100mg twice daily for 7 days. 2, 3, 4
When to Prioritize Azithromycin Over Doxycycline
Azithromycin should be selected as first-line therapy in specific clinical scenarios: 5, 2
- Compliance concerns: Patients with erratic health-care-seeking behavior or poor adherence to multi-day regimens
- Directly observed therapy: Single-dose administration allows on-site dispensing with witnessed first dose
- Cost-effectiveness in high-risk populations: Despite higher drug cost, azithromycin reduces overall costs when follow-up is unpredictable
Mechanism of Superior Compliance
The pharmacokinetic profile explains azithromycin's single-dose efficacy: 3, 6
- Tissue half-life of 2-4 days maintains therapeutic concentrations
- High intracellular accumulation targets Chlamydia trachomatis (an obligate intracellular pathogen)
- Minimum inhibitory concentration of 0.03-0.25 mg/L against chlamydia
Pediatric Indications for 1g Dose
Children ≥8 years weighing >45 kg receive the adult dose of azithromycin 1g single dose for chlamydial infections. 5, 7
Children <8 years but weighing >45 kg also receive azithromycin 1g single dose, as this is the only recommended regimen (doxycycline is contraindicated under age 8). 5, 7
Pregnancy Considerations
Azithromycin 1g single dose is the preferred first-line treatment for chlamydial infections during pregnancy. 2 Doxycycline and all fluoroquinolones are absolutely contraindicated in pregnancy. 2
Gonorrhea Treatment: Critical Limitation
The FDA label lists "gonococcal urethritis and cervicitis" as requiring a 2-gram single dose, NOT 1 gram. 1 However, this recommendation is outdated and should not be used in current practice due to widespread azithromycin resistance in Neisseria gonorrhoeae. Current guidelines recommend ceftriaxone 250-500mg IM as first-line therapy for gonorrhea. 2
One older study showed azithromycin 1g had only 98.8% efficacy (2/170 failures) for gonorrhea, which is unacceptably low by modern standards. 8
Essential Treatment Execution
To maximize cure rates and prevent reinfection: 5, 2
- Dispense medication on-site and directly observe the first (and only) dose
- Patients must abstain from sexual intercourse for 7 days after taking azithromycin
- All sex partners from the preceding 60 days must receive empiric treatment without waiting for test results
- No test-of-cure is needed for non-pregnant patients treated with azithromycin unless symptoms persist or reinfection is suspected
Common Clinical Pitfall
Do not use azithromycin 1g for gonorrhea monotherapy in current practice. Despite FDA labeling, resistance patterns have rendered azithromycin unreliable as single-agent therapy for N. gonorrhoeae. When gonorrhea and chlamydia coinfection is suspected or confirmed, treat with ceftriaxone 250mg IM PLUS azithromycin 1g orally. 2