Ilosone (erythromycin estolate) is a well-established macrolide antibiotic indicated for the treatment of a wide range of susceptible bacterial infections. With a proven history of clinical efficacy, it functions by inhibiting bacterial protein synthesis, leading to bacteriostatic action against gram-positive and some gram-negative organisms. Its estolate formulation offers enhanced acid stability and improved oral absorption, making it a reliable choice for outpatient management. Healthcare providers trust Ilosone for its targeted spectrum and favorable pharmacokinetic profile in both adult and pediatric populations.

Features

• Active ingredient: Erythromycin estolate
• Drug class: Macrolide antibiotic
• Available forms: Oral tablets (250 mg, 500 mg), oral suspension (125 mg/5 mL, 250 mg/5 mL)
• Mechanism: Binds to the 50S ribosomal subunit, inhibiting bacterial protein synthesis
• Spectrum: Effective against Streptococcus pyogenes, Streptococcus pneumoniae, Staphylococcus aureus (methicillin-susceptible), Corynebacterium diphtheriae, and others
• Prescription status: Rx-only

Benefits

• Effectively treats respiratory tract infections, including pharyngitis, tonsillitis, and acute bronchitis
• Provides reliable coverage for skin and soft tissue infections caused by susceptible staphylococcal and streptococcal strains
• Suitable for patients with penicillin allergy, serving as an alternative therapeutic option
• Offers flexible dosing formulations for both adults and pediatric patients
• Demonstrates good tissue penetration, reaching effective concentrations at sites of infection
• Supported by decades of clinical use and established safety data

Common use

Ilosone is commonly prescribed for bacterial infections such as:

• Upper and lower respiratory tract infections (e.g., streptococcal pharyngitis, community-acquired pneumonia)
• Skin and soft tissue infections (e.g., impetigo, erysipelas, cellulitis)
• Pertussis (whooping cough) as prophylaxis or treatment
• Diphtheria (as adjunctive therapy to antitoxin)
• Erythrasma
• Legionnaires’ disease
• Syphilis (in penicillin-allergic patients)

Dosage and direction

Dosage must be individualized based on infection severity, pathogen susceptibility, and patient factors.

Adults:
Typical dosage is 250 mg orally every 6 hours, or 500 mg every 12 hours. For more severe infections, 500 mg every 6 hours may be required. Treatment should generally continue for at least 10 days in streptococcal infections.

Children:
30–50 mg/kg/day in divided doses every 6–8 hours. Maximum dose should not exceed adult recommendations.

Administer on an empty stomach (1 hour before or 2 hours after meals) for optimal absorption, unless gastrointestinal intolerance occurs, in which case administration with food may be considered.

Precautions

• Use with caution in patients with hepatic impairment due to primarily hepatic metabolism and excretion
• Monitor for signs of hepatotoxicity; discontinue if symptoms such as jaundice, dark urine, or abdominal pain occur
• May prolong QT interval; use caution in patients with known QT prolongation, electrolyte abnormalities, or those taking other QT-prolonging drugs
• Superinfection with nonsusceptible organisms, including fungi, may occur
• Not recommended for empiric treatment in regions with high erythromycin resistance rates
• Use during pregnancy only if clearly needed (Category B)
• Excreted in breast milk; consider benefits versus risks during lactation

Contraindications

• Known hypersensitivity to erythromycin or any macrolide antibiotic
• Patients with pre-existing hepatic disease or history of erythromycin-associated hepatitis
• Concurrent administration with ergot derivatives, cisapride, pimozide, or terfenadine due to risk of serious cardiac adverse events
• Concomitant use with colchicine in patients with renal or hepatic impairment

Possible side effect

Common adverse reactions may include:

• Gastrointestinal: Nausea, vomiting, abdominal cramping, diarrhea
• Hepatic: Elevated liver enzymes, cholestatic hepatitis (usually reversible upon discontinuation)
• Hypersensitivity reactions: Rash, urticaria, eosinophilia
• Other: Ototoxicity (with high doses or renal impairment), QT prolongation, pseudomembranous colitis

Drug interaction

Ilosone may interact with:

• CYP3A4 substrates: Increased concentrations of drugs such as simvastatin, lovastatin, sildenafil
• Anticoagulants: Potentiation of warfarin effect
• Theophylline: Increased theophylline levels
• Digoxin: Increased digoxin absorption
• Cyclosporine: Elevated cyclosporine concentrations
• Oral contraceptives: Possible reduced efficacy
• Ergot alkaloids: Risk of ergotism
• Other QT-prolonging agents: Additive effects on cardiac repolarization

Missed dose

If a dose is missed, take it as soon as remembered. If it is nearly time for the next dose, skip the missed dose and resume the regular schedule. Do not double the dose to make up for a missed one.

Overdose

Symptoms may include severe nausea, vomiting, diarrhea, and hearing loss. Hepatotoxicity may occur. Treatment is supportive; gastric lavage may be considered if ingestion was recent. No specific antidote exists. Hemodialysis is not effective for removal.

Storage

Store at controlled room temperature (20–25°C or 68–77°F). Keep container tightly closed. Protect from moisture and light. Do not freeze oral suspension. Discard any unused suspension after 14 days.

Disclaimer

This information is for educational purposes only and does not replace professional medical advice. Always consult a healthcare provider for diagnosis and treatment recommendations. Do not initiate, adjust, or discontinue medication without medical supervision.

Reviews

“Ilosone remains a valuable option for penicillin-allergic patients with streptococcal infections. Its predictable spectrum and generally tolerable profile make it a workhorse in outpatient practice.” – Infectious Disease Specialist, 15 years experience

“While newer macrolides exist, erythromycin estolate continues to serve an important role, particularly in pediatric populations where suspension formulations are preferable.” – Pediatric Pharmacist

“Monitoring for gastrointestinal side effects and hepatotoxicity is essential, but most patients tolerate therapy well when appropriately selected.” – General Practitioner