Ilosone (erythromycin estolate) is a time-tested, highly effective macrolide antibiotic prescribed for a wide range of bacterial infections. As an estolate salt of erythromycin, it offers enhanced oral bioavailability and stability in gastric acid, ensuring reliable systemic delivery. Trusted by healthcare professionals for decades, Ilosone targets susceptible organisms with precision, making it a cornerstone in outpatient and inpatient therapeutic regimens. Its established efficacy and safety profile support its continued use in modern antimicrobial therapy.

Features

• Active ingredient: Erythromycin estolate
• Drug class: Macrolide antibiotic
• Available formulations: 250 mg and 500 mg tablets; oral suspension (125 mg/5 mL and 250 mg/5 mL)
• Mechanism of action: Binds to the 50S ribosomal subunit, inhibiting bacterial protein synthesis
• Spectrum: Effective against Gram-positive bacteria, some Gram-negative bacteria, and atypical pathogens
• Prescription status: Rx-only medication

Benefits

• Effectively treats respiratory tract infections, including pneumonia, bronchitis, and pertussis
• Provides reliable coverage for skin and soft tissue infections caused by susceptible Staphylococcus and Streptococcus species
• Suitable for patients with penicillin allergies, serving as an important alternative
• Demonstrates good tissue penetration, reaching therapeutic concentrations at infection sites
• Oral formulation allows for convenient outpatient treatment, supporting medication adherence
• Established resistance profile enables informed clinical decision-making

Common use

Ilosone is indicated for the treatment of various bacterial infections caused by susceptible strains of microorganisms. Common uses include upper and lower respiratory tract infections such as pharyngitis, tonsillitis, acute bronchitis, and community-acquired pneumonia. It is also effective for skin and soft tissue infections including impetigo, erysipelas, and cellulitis. Additionally, Ilosone is used in the management of pertussis (whooping cough), diphtheria (as an adjunct to antitoxin), and erythrasma. It may be prescribed for Legionnaires’ disease, chlamydial infections, and as prophylaxis against rheumatic fever in penicillin-allergic patients.

Dosage and direction

Dosage must be individualized based on the severity of infection and the patient’s clinical status. For adults, the usual dosage ranges from 250 mg to 500 mg every 6 hours, or 500 mg to 1,000 mg every 12 hours for more severe infections. The maximum recommended daily dose is 4 grams. For children, the dosage is typically 30-50 mg/kg/day divided into 3-4 equal doses. For pertussis, the recommended dosage is 40-50 mg/kg/day, maximum 2 g/day, for 14 days. Tablets should be swallowed whole with a full glass of water; the oral suspension should be shaken well before each use. Ilosone may be taken with food to minimize gastrointestinal upset, though absorption may be slightly reduced. Complete the full course of therapy even if symptoms improve earlier to prevent antibiotic resistance.

Precautions

Use Ilosone with caution in patients with hepatic impairment due to the risk of drug accumulation and potential hepatotoxicity. Monitor liver function tests periodically during prolonged therapy. Exercise caution in patients with renal impairment; dosage adjustment may be necessary. May prolong the QT interval; use with caution in patients with known QT prolongation, electrolyte imbalances, or those taking other QT-prolonging drugs. Superinfections with nonsusceptible organisms, including fungi, may occur; discontinue therapy if superinfection is suspected. Not recommended for the treatment of meningitis due to inadequate cerebrospinal fluid penetration. Use during pregnancy only if clearly needed (Category B). Erythromycin excretes in breast milk; consider temporary discontinuation of nursing during treatment.

Contraindications

Ilosone is contraindicated in patients with known hypersensitivity to erythromycin, any other macrolide antibiotics, or any component of the formulation. Contraindicated in patients with pre-existing liver disease or hepatic dysfunction due to the risk of erythromycin estolate-induced hepatotoxicity. Should not be used concomitantly with drugs that are extensively metabolized by CYP3A4 and have narrow therapeutic indices, including cisapride, pimozide, ergot alkaloids, and terfenadine, due to risk of serious cardiac adverse events. Not recommended for patients with known QT prolongation or ventricular arrhythmias, including torsades de pointes.

Possible side effect

Common side effects include gastrointestinal disturbances such as nausea, vomiting, abdominal pain, diarrhea, and anorexia. These typically diminish as treatment continues. Less frequently, patients may experience mild allergic reactions including skin rash, urticaria, and pruritus. Hepatotoxicity may occur, characterized by elevated liver enzymes, jaundice, or hepatitis-like symptoms. Ototoxicity, manifesting as reversible hearing loss, has been reported, particularly at high doses or in patients with renal impairment. Prolonged use may result in oral or vaginal candidiasis. Rare but serious side effects include QT prolongation, ventricular arrhythmias, Clostridium difficile-associated diarrhea, and severe skin reactions such as Stevens-Johnson syndrome.

Drug interaction

Ilosone inhibits CYP3A4 metabolism, potentially increasing concentrations of numerous medications including anticoagulants (warfarin), anticonvulsants (carbamazepine), benzodiazepines, statins (lovastatin, simvastatin), and immunosuppressants (cyclosporine, tacrolimus). Concomitant use with other QT-prolonging agents (antiarrhythmics, antipsychotics, antidepressants) may increase arrhythmia risk. May reduce the effectiveness of oral contraceptives; recommend alternative contraception during therapy. Absorption may be impaired by antacids containing aluminum or magnesium; administer Ilosone至少1 hour before or 2 hours after these products. May potentiate digitalis toxicity. Concurrent use with theophylline may increase theophylline concentrations.

Missed dose

If a dose is missed, take it as soon as remembered unless it is almost time for the next scheduled dose. In that case, skip the missed dose and resume the regular dosing schedule. Do not double the dose to make up for a missed administration. Maintaining consistent antibiotic levels is important for efficacy, but occasional missed doses are unlikely to significantly impact treatment outcomes if the regular schedule is promptly resumed. If multiple doses are missed, contact your healthcare provider for guidance.

Overdose

Symptoms of overdose may include severe nausea, vomiting, diarrhea, and abdominal pain. Hepatotoxicity may be exacerbated. Ototoxicity, manifested as hearing loss, tinnitus, or vertigo, may occur. In severe cases, QT prolongation and ventricular arrhythmias might develop. Management is primarily supportive and symptomatic. Gastric lavage may be considered if ingestion was recent. There is no specific antidote; maintain hydration and electrolyte balance. Hemodialysis is not effective for removal of erythromycin. Monitor ECG for QT prolongation and provide cardiac monitoring if arrhythmias are suspected. Contact a poison control center immediately for guidance.

Storage

Store at controlled room temperature (20-25°C or 68-77°F); excursions permitted to 15-30°C (59-86°F). Keep the container tightly closed to protect from moisture and light. The oral suspension remains stable for 14 days at room temperature after reconstitution; do not freeze. Keep all medications out of reach of children and pets. Do not use beyond the expiration date printed on the packaging. Properly discard any unused medication after completing treatment or after the expiration date has passed.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Ilosone is a prescription medication that should be used only under the supervision of a qualified healthcare professional. The prescribing physician should be consulted for diagnosis, treatment decisions, and individualized dosing recommendations. Actual product characteristics, indications, and safety information may vary by country and regulatory approval. Always read the accompanying patient information leaflet and follow your healthcare provider’s instructions.

Reviews

Clinical studies and decades of therapeutic use demonstrate Ilosone’s consistent efficacy in treating susceptible bacterial infections. Healthcare professionals appreciate its reliability as a penicillin alternative and its predictable pharmacokinetic profile. Patients generally report satisfactory outcomes when the full course is completed as directed. Some reviews note gastrointestinal side effects as a common concern, though these are typically manageable. The established safety profile makes it a preferred choice in appropriate patient populations. Ongoing monitoring continues to support its favorable benefit-risk ratio in indicated infections.