Erythromycin: Uses, dosage, side effects, warnings & patient reviews

What is Erythromycin?

Erythromycin is a macrolide antibiotic derived from the bacterium Streptomyces erythreus. It works by inhibiting bacterial protein synthesis, thereby stopping the growth of susceptible bacteria.

As a member of the antibiotics class, erythromycin is effective against many Gram-positive and some Gram-negative bacteria. It is often prescribed as an alternative for patients who have a confirmed allergy to penicillin-based antibiotics, such as ampicillin.

Key Considerations

While effective, oral erythromycin is associated with a high incidence of gastrointestinal side effects, such as nausea, vomiting, and abdominal cramping, due to its stimulatory effect on gut motility. Its use requires careful consideration of potential drug interactions, as it can significantly affect the metabolism of many other medications.

How to Take Erythromycin

Following administration instructions precisely is crucial for effectiveness and to minimize common gastrointestinal side effects.

Administration and Timing

Shake the oral suspension well before measuring each dose with the provided measuring device. Erythromycin tablets should be swallowed whole with a full glass of water.

For most oral forms, taking the medication with food or milk can help reduce stomach upset. However, the absorption of certain salt forms (like erythromycin base) may be impaired by food. Always follow the specific instructions on your prescription label regarding food.

Course Completion

It is critical to complete the entire prescribed course of antibiotics, even if you start to feel better after a few days. Stopping treatment early can lead to a resurgence of the infection and contribute to antibiotic resistance. For a broader understanding of this principle, see our guide on responsible antibiotic use.

Missed Dose

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not take a double dose to make up for a missed one.

Side Effects of Erythromycin

Erythromycin is associated with a range of side effects, with gastrointestinal issues being particularly common. It’s helpful to understand the spectrum of possible reactions.

What is Erythromycin Used For?

Erythromycin is prescribed for various bacterial infections caused by susceptible organisms.

Primary Medical Uses

• Respiratory Tract Infections: Including pharyngitis, bronchitis, and atypical pneumonia (e.g., caused by *Mycoplasma pneumoniae*).
• Skin and Soft Tissue Infections: Such as mild to moderate acne, impetigo, and cellulitis. Erythromycin for acne is often used in topical gel form.
• Sexually Transmitted Infections (STIs): A treatment option for chlamydia, particularly in pregnant patients.
• Prevention of Infection: Used before certain surgical/dental procedures to prevent endocarditis in penicillin-allergic patients.
• Ophthalmic Infections: Erythromycin eye ointment is used to treat bacterial eye infections and is routinely applied to newborns to prevent ophthalmia neonatorum.

Important Clarification

Erythromycin is ineffective against viral infections like the common cold or flu. It should only be used for bacterial infections confirmed or strongly suspected by a healthcare provider.

Important Safety Concerns and Considerations

QT Prolongation and Cardiac Risk

Erythromycin can prolong the QT interval on an electrocardiogram, which may lead to a serious irregular heart rhythm (torsades de pointes). This risk is increased in patients with:

• Pre-existing heart conditions or a family history of Long QT Syndrome.
• Low blood levels of potassium or magnesium.
• Concurrent use of other medications that also prolong the QT interval.

Symptoms include palpitations, dizziness, and fainting.

Hepatotoxicity

Erythromycin, particularly the estolate salt, has been associated with cholestatic hepatitis. Symptoms include jaundice (yellowing of skin/eyes), dark urine, clay-colored stools, and abdominal pain. Liver function usually returns to normal after discontinuation of the drug.

Clostridioides difficile-Associated Diarrhea (CDAD)

Antibiotic use, including erythromycin, can disrupt normal gut flora and allow overgrowth of *C. difficile*, leading to diarrhea that can range from mild to life-threatening colitis. CDAD can occur even weeks after finishing antibiotics.

Hearing Loss

Reversible hearing loss, sometimes accompanied by tinnitus (ringing in the ears), has been reported, usually with high doses or in patients with kidney or liver impairment. Hearing typically returns to normal after stopping the drug.

Critical Warnings for Erythromycin Use

Serious Drug Interactions

Erythromycin is a strong inhibitor of the CYP3A4 enzyme system. Concomitant use with drugs metabolized by this pathway can lead to dangerously elevated levels of those drugs, increasing the risk of serious adverse events. This includes certain statins (risk of rhabdomyolysis), antiarrhythmics (risk of fatal arrhythmias), benzodiazepines (increased sedation), and warfarin (increased bleeding risk). A thorough medication review is mandatory.

Exacerbation of Myasthenia Gravis

Erythromycin may worsen muscle weakness in patients with myasthenia gravis and should be used with extreme caution, if at all, in this population.

Risk of Infantile Hypertrophic Pyloric Stenosis (IHPS)

The use of erythromycin in neonates and young infants (below 2 weeks of age) has been associated with an increased risk of IHPS, a condition that causes projectile vomiting and requires surgical correction. Use in this age group should be reserved for well-documented, high-benefit situations.

Pseudomembranous Colitis

As with nearly all antibacterial agents, erythromycin use may result in the overgrowth of non-susceptible organisms, including *C. difficile*. Mild cases may respond to drug discontinuation; severe cases require specific therapy.

Erythromycin Dosage Information

Dosage varies widely based on the infection being treated, the patient’s age and weight, and the specific salt form of erythromycin. Always follow your doctor’s specific prescription.

Important Administration Notes

• Salt Equivalency: 400 mg of erythromycin ethylsuccinate is approximately equivalent to 250 mg of erythromycin base. Dosing instructions refer to the salt form prescribed.
• Pediatric Dosage: Typically 30-50 mg/kg/day of erythromycin ethylsuccinate in divided doses. Use the provided measuring device for the erythromycin suspension.
• Topical Forms: Erythromycin ointment or gel for acne is typically applied to affected areas once or twice daily as directed.
• With or Without Food: Taking with food can reduce stomach upset, but may impair absorption of some salt forms. Follow label instructions.

Drug Interactions with Erythromycin

Erythromycin has a high potential for significant drug interactions due to its inhibition of the CYP3A4 enzyme. Inform your doctor about all medications and supplements you take.

Additional Information

Historical Fact

Erythromycin was discovered in 1952 from a soil sample collected in the Philippines. It was the first macrolide antibiotic brought to market and became a critically important therapeutic agent, especially for patients allergic to penicillin. Its discovery highlighted the continued potential of soil microorganisms as sources of novel medicines.

Storage and Handling

Store erythromycin tablets and capsules at room temperature. The oral suspension should be stored according to the label (some require refrigeration after reconstitution) and any unused portion discarded after the directed number of days. Topical ointments and gels should be stored at room temperature. Keep all medications out of reach of children.

Obtaining Medication Safely

Erythromycin is a prescription-only medication. It should only be obtained with a valid prescription from a licensed healthcare provider who has evaluated your infection. Do not use leftover antibiotics from a previous illness or share your medication with others.

References and Medical Sources

The information on this page is compiled from reputable medical sources and prescribing information.

1. U.S. Food and Drug Administration (FDA). Erythromycin Prescribing Information. [Various dates]. https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/050536s026lbl.pdf
2. MedlinePlus. Erythromycin. U.S. National Library of Medicine; [Updated 2017]. https://medlineplus.gov/druginfo/meds/a682381.html
3. Drugs.com. Erythromycin Professional Monograph. Drugs.com; [Updated 2024]. https://www.drugs.com/monograph/erythromycin.html
4. World Health Organization (WHO). WHO Model List of Essential Medicines. Erythromycin. [Updated 2023]. https://www.who.int/publications/i/item/WHO-MHP-HPS-EML-2023.02

Disclaimer: The information on this site is provided for informational purposes only and is not medical advice. It does not replace professional medical consultation, diagnosis, or treatment. Do not self-medicate based on the information presented on this site. Always consult with a doctor or other qualified healthcare professional before making any decisions about your health.