Adult Liquid Azithromycin Dosage in Milliliters
The milliliter volume depends entirely on the concentration of your liquid azithromycin formulation, but standard adult dosing is 500 mg on day 1, followed by 250 mg daily for days 2-5 for most bacterial infections. 1, 2
Converting Milligrams to Milliliters
To determine the exact mL dose, you must know the concentration of your specific liquid formulation:
If concentration is 200 mg/5 mL (40 mg/mL):
- Day 1: 500 mg = 12.5 mL
- Days 2-5: 250 mg = 6.25 mL 1
If concentration is 100 mg/5 mL (20 mg/mL):
- Day 1: 500 mg = 25 mL
- Days 2-5: 250 mg = 12.5 mL
Standard Adult Dosing Regimens by Indication
Most Common Infections (Respiratory, Skin/Soft Tissue)
- 500 mg on day 1, then 250 mg once daily for 4 additional days (total 5-day course) 1, 2
- This regimen maintains therapeutic tissue concentrations for several days after the last dose due to azithromycin's prolonged tissue half-life 3, 4
Sexually Transmitted Infections
- Single 1-gram dose for non-gonococcal urethritis, cervicitis, and Chlamydia trachomatis 1, 2
- This equals 50 mL if using 200 mg/5 mL concentration or 25 mL if using 100 mg/5 mL concentration
Severe or Prolonged Infections
- 500 mg daily for 3 days for acute exacerbations of chronic bronchitis 5
- 500 mg daily for 7-10 days for babesiosis (in combination with atovaquone), with 500-1000 mg on day 1 6, 2
- For immunocompromised patients with babesiosis, higher doses of 600-1000 mg daily may be used 6
Critical Administration Considerations
Timing with antacids: Do not administer azithromycin simultaneously with aluminum- or magnesium-containing antacids, as they reduce absorption by up to 50%; separate by at least 2 hours 6, 2, 7
Food effects: While azithromycin can be taken with or without food, coadministration with a large meal may reduce absorption by up to 50% 1, 7
Cardiac screening: Before initiating therapy, especially in patients with cardiac risk factors, perform an ECG to assess QTc interval; avoid azithromycin if QTc is >450 ms for men or >470 ms for women 8
Common Pitfalls to Avoid
- Do not assume all liquid formulations have the same concentration - always verify the mg/mL strength on the bottle label before calculating the mL dose
- Do not use azithromycin as monotherapy for gonococcal infections due to resistance concerns; combination with ceftriaxone is required 1
- Do not underdose in severe infections - the standard 5-day regimen may be insufficient for immunocompromised hosts or severe infections requiring 7-10 days 8