Dosing & Uses
Dosing Form & Strengths
tablet
- 250mg
General Dosing Recommendations
250 mg PO q6hr, OR
500 mg PO q12hr (if daily dose does not exceed 1 g)
May increase up to 4 g/day depending on infection severity
Amebiasis
500 mg PO q6hr for 10-14 days
Legionnaires Disease
1-4 g/day PO in divided doses for 21 days
Urethritis
Urethritis caused by C trachomatis or U urealyticum
500 mg PO q6hr for 7 days; alternatively 333 mg PO q8hr for 7 days
Syphilis
30-40 g PO in divided doses for 10-15 days
Renal Impairment
Dose adjustment not necessary
Hepatic Impairment
Use caution
Other Indications & Uses
Group A beta-hemolytic strep, Actinobacillus actinomycetemcomitans, Actinomyces israelii, Actinomyces naeslundii, Actinomyces odontolyticus, Afipia felis, Arachnia propionica, Arcanobacterium (Corynebacterium) haemolyticum, Bacillus anthracis, Bartonella henselae, Bartonella quintana, Bordetella pertussis, Borrelia burgdorferi, Borrelia recurrentis, C. diphtheriae, C. trachomatis, Klebsiella granulomatis, Campylobacter jejuni, Capnocytophaga ochracea, Chlamydia pneumonia (TWAR agent), Chlamydia psittaci, Chlamydia trachomatis, Chryseobacterium meningosepticum, Corynebacterium jeikeium (CDC group JK), Corynebacterium minutissimum, Corynebacterium ulcerans, Coxiella burnetii, E. histolytica, Erysipelothrix rhusiopathiae, H. ducreyi, H. influenzae, Kingella sp., Lactobacillus sp, Legionella pneumophilia, Leptospira interrogans, Leptotrichia buccalis, Leuconostoc species, Listeria, Mycobacterium chelonae, Mycobacterium fortuitum, M. catarrhalis, Mycoplasma pneumoniae, N. gonorrhoeae, Rhodococcus equi, S. aureus, S. pyogenes (group A beta-hemolytic streptococci), S. pneumoniae, Spirillum minus, Streptobacillus moniliformis, Streptococcus (Group C, G), Streptococcus agalactiae (Group B), Streptococcus bovis (Group D), Streptococcus intermedius group (S. anginosus, S intermedius, S. constellatus), Streptococcus pneumoniae (PCN sensitive, MIC <0.1 mcg/mL), Streptococcus pyogenes (Group A), Treponema pallidum, U. urealyticum, Ureaplasma urealyticum, Vibrio cholerae, Viridans streptococci
Off-label: Campylobacter jejuni, Calymmatobacterium granulomatis, Haemophilus ducreyi, prophylaxis in colorectal surgery, anthrax, tetanus, Lyme disease
First line: Afipia felis, Arcanobacterium (Corynebacterium) haemolyticum, Bartonella henselae, Bartonella quintana, Campylobacter jejuni, Capnocytophaga ochracea, Chlamydia pneumonia, Corynebacterium minutissimum, Corynebacterium ulcerans, Haemophilus ducreyi, Mycobacterium fortuitum, Ureaplasma urealyticum (others eg, Haemophilus ducreyi not unanimous)
Dosing Form & Strengths
tablet
- 250mg
General Dosing Recommendations
Mild-to-moderate infections: 30-50 mg/kg/day PO divided q6-8hr
Severe infection: 60-100 mg/kg/day PO divided q6-8hr
Not to exceed 4 g/day
Intestinal Amebiasis
30-50 mg/kg/day PO in divided doses for 10-14 days
Pneumonia of Infancy
50 mg/kg/day PO divided q6hr for at least 3 weeks
Interactions
Interaction Checker
No Results

Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor

Adverse Effects
1-10%
Abdominal pain (8%)
Headache (8%)
Nausea (8%)
Diarrhea (7%)
Rash (3%)
Vomiting (3%)
Dyspepsia (2%)
Flatulence (2%)
Pain (2%)
Pruritus (1%)
Pseudomembranous colitis
Hypertrophic pyloric stenosis
Anaphylaxis
Fever
Mild allergic reactions
Urticaria
Skin eruptions
Tinnitus
<1%
Cholestatic hepatitis
Confusion
Hallucinations
Hearing loss
Hypotension
Nervous system effects including seizures
Torsade de pointes
Ventricular tachycardia
Vertigo
Postmarketing reports
Interstitial nephritis
Warnings
Contraindications
Documented hypersensitivity
Coadministration with terfenadine
Coadministration with HMG-CoA reductase inhibitors that are extensively metabolized by CYP3A4 (lovastatin or simvastatin)
Co-administration of erythromycin with ergotamine or dihydroergotamine
Cautions
Hepatic dysfunction, including increased liver enzymes, and hepatocellular and/or cholestatic hepatitis, with or without jaundice reported in patients receiving oral erythromycin products
Prescribing therapy in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to patient and increases risk of development of drug-resistant bacteria
Since erythromycin is principally excreted by the liver, caution should be exercised when erythromycin is administered to patients with impaired hepatic function
Exacerbation of symptoms of myasthenia gravis and new onset of symptoms of myasthenic syndrome reported in patients receiving erythromycin therapy
Infantile hypertrophic pyloric stenosis (IHPS) in infants following erythromycin therapy reported; a possible dose-response effect reported; since erythromycin may be used in the treatment of conditions in infants which are associated with significant mortality or morbidity (such as pertussis or neonatal Chlamydia trachomatis infections), the benefit of therapy needs to be weighed against potential risk of developing IHPS; parents should be informed to contact their physician if vomiting or irritability with feeding occurs
Prolonged or repeated use of erythromycin may result in an overgrowth of nonsusceptible bacteria or fungi; if superinfection occurs, erythromycin should be discontinued, and appropriate therapy instituted
When indicated, incision and drainage or other surgical procedures should be performed in conjunction with antibiotic therapy; observational studies in humans have reported cardiovascular malformations after exposure to drug products containing erythromycin during early pregnancy
QT Prolongation
- Therapy has been associated with prolongation of QT interval and infrequent cases of arrhythmia; elderly patients may be more susceptible to drug-associated effects on QT interval
- Cases of torsades de pointes spontaneously reported during postmarketing surveillance in patients receiving erythromycin; fatalities reported
- Therapy should be avoided in patients with known prolongation of QT interval, patients with ongoing proarrhythmic conditions such as uncorrected hypokalemia or hypomagnesemia, clinically significant bradycardia, and patients receiving Class IA (quinidine, procainamide) or Class III (dofetilide, amiodarone, sotalol) antiarrhythmic agents
Syphilis in pregnancy
- There have been reports suggesting erythromycin does not reach the fetus in adequate concentration to prevent congenital syphilis; infants born to women treated during pregnancy with oral erythromycin for early syphilis should be treated with appropriate penicillin regimen
Clostridium difficile associated diarrhea
- Clostridium difficile associated diarrhea (CDAD) reported with use of nearly all antibacterial agents, including erythromycin and may range in severity from mild diarrhea to fatal colitis
- Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile; C. difficile produces toxins A and B which contribute to development of CDAD
- Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy
- CDAD must be considered in all patients who present with diarrhea following antibiotic use; careful medical history is necessary since CDAD has been reported to occur over two months after administration of antibacterial agents
- If CDAD is suspected or confirmed, ongoing antibiotic use not directed against C. difficile may need to be discontinued; appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated
Drug interaction overview
- There have been post-marketing reports of cardiac arrhythmias, ventricular tachycardia, ventricular fibrillation, and torsades de pointes, caused by coadministration of drugs that result in QT prolongation; fatalities reported
- Increased anticoagulant effects, which may be more pronounced in elderly when erythromycin and oral anticoagulants (eg, warfarin) are used concomitantly, reported
- Colchicine is a substrate for both CYP3A4 and the efflux transporter P-glycoprotein (P-gp); erythromycin is considered moderate inhibitor of CYP3A4; a significant increase in colchicine plasma concentration is anticipated when co-administered with moderate CYP3A4 inhibitors such as erythromycin; if coadministration of colchicine and erythromycin is necessary, may need to reduce starting dose of colchicine, and maximum colchicine dose lowered; monitor patients for clinical symptoms of colchicine toxicity
- Erythromycin may increase systemic exposure (AUC) of sildenafil; consider reduction of sildenafil dosage
- Erythromycin may decrease clearance of triazolam, midazolam and related benzodiazepines, increasing their effect
- Post-marketing reports indicate that co-administration with ergotamine or dihydroergotamine has been associated with acute ergot toxicity characterized by vasospasm and ischemia of central nervous system, extremities and other tissues
Pregnancy & Lactation
Pregnancy Category: B
Lactation: distributed in breast milk, use with caution; AAP categorizes as compatible with breastfeeding
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest
Absorption
Oral: variable but better with salt forms than with base form
Peak Plasma Time: 4 hr (base)
Distribution
Protein Bound: 75-80%
Crosses placenta; enters breast milk
Relative diffusion from blood into CSF: minimal even with inflammation
Metabolism
Via P450 enzyme CYP3A4
Enzymes inhibited: CYP1A2, CYP3A4
Elimination
Half-Life: 1.4 hr
Excretion: Primarily feces; urine (2-15% as unchanged drug)
Images
BRAND | FORM. | UNIT PRICE | PILL IMAGE |
---|---|---|---|
erythromycin stearate oral - | 250 mg tablet | ![]() | |
Erythrocin (as stearate) oral - | 250 mg tablet | ![]() | |
Erythrocin (as stearate) oral - | 250 mg tablet | ![]() |
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