Erythromycin Dosage and Treatment Duration
For adults, erythromycin is typically dosed at 500 mg four times daily for 7 days, while children require 50 mg/kg/day divided into four doses daily for 14 days. 1, 2
Adult Dosing
- Standard adult dosage is 500 mg four times daily or 500 mg every 12 hours 2
- For Chlamydia trachomatis infections, the recommended dose is 500 mg four times daily for 7 days 1
- For urogenital infections during pregnancy due to Chlamydia trachomatis, 500 mg four times daily on an empty stomach for at least 7 days is recommended 2
- For women who cannot tolerate this regimen, a decreased dose of 500 mg every 12 hours or 250 mg four times daily for at least 14 days can be used 2
- For pertussis, the recommended dose is 2 g daily divided into 4 doses for 14 days 1
- For Legionnaires' disease, doses of 1-4 g daily in divided doses have been utilized 2
Pediatric Dosing
- For children who weigh <45 kg: Erythromycin base or ethylsuccinate 50 mg/kg/day orally divided into four doses daily for 14 days 3
- For children who weigh >45 kg but are <8 years of age: Azithromycin 1 g orally in a single dose is preferred 3
- For children ≥8 years of age: Azithromycin 1 g orally in a single dose OR doxycycline 100 mg orally twice daily for 7 days 3
- For infants with Chlamydia pneumonia: Erythromycin base or ethylsuccinate 50 mg/kg/day orally divided into four doses daily for 14 days 3
- The FDA recommends 30-50 mg/kg/day in equally divided doses for children, with dosage potentially doubled for severe infections (not to exceed 4 g per day) 2
Special Considerations
- Erythromycin should be taken on an empty stomach, preferably 2 hours before meals, for optimal absorption 2
- The effectiveness of erythromycin in treating Chlamydia pneumonia is approximately 80%; a second course of therapy may be required 3
- Follow-up is recommended for infants with chlamydial pneumonia to ensure resolution 3
- For streptococcal infections of the upper respiratory tract, erythromycin should be administered for at least 10 days 2
- Erythromycin estolate should be avoided during pregnancy due to risk of hepatotoxicity 1
Common Adverse Effects
- Gastrointestinal symptoms (nausea, vomiting, abdominal pain, diarrhea) are the most common side effects 1
- Higher doses increase the risk of adverse effects 1
- There is an increased risk of infantile hypertrophic pyloric stenosis in neonates during the month following erythromycin administration 1
Treatment Duration Considerations
- For most adult infections: 7 days 1, 2
- For children with Chlamydia infections: 14 days 3
- For pertussis: 14 days 1, 2
- For intestinal amebiasis: 10-14 days 2
Clinical Pearls
- Erythromycin is less preferred than azithromycin for many infections due to its more frequent dosing schedule and greater gastrointestinal side effects 4, 5
- A 7-day course of erythromycin has been shown to be significantly more effective than a 4-day course for treating Chlamydia trachomatis infections 6
- Follow-up cultures are necessary to ensure treatment has been effective, especially in children 3