Erythromycin Base

Reviewed on 5/18/2022

What Is Erythromycin Base and How Does It Work?

Erythromycin Base is a prescription antibiotic medication used to treat the symptoms of bacterial infections.

  • Erythromycin Base  is available under the following different brand names: Ery-Tab, PCE Dispertab

What Are Dosages of Erythromycin Base?

Adult and pediatric dosage


  • 250mg
  • 500mg

Tablet, delayed-release particles

  • 250mg
  • 333mg
  • 500mg

Capsule, delayed-release particles

  • 250mg

PCE Dispertab

  • 333mg
  • 500mg

Legionnaires Disease

Adult dosage

  • 1-4 g/day orally in divided doses for 21 days

Nongonococcal Urethritis

Adult dosage

  • 500 mg orally every 6 hours for 7 days

Bowel Preparation

Adult dosage

  • 1 g orally at 1:00, 2:00, and 11:00 PM on the day before surgery in combination with oral neomycin and mechanical cleansing of the large intestine

Pediatric dosage

  • 20 mg/kg orally at 1:00, 2:00, and 11:00 PM on the day before surgery in combination with oral neomycin and mechanical cleansing of the large intestine

Lymphogranuloma Venereum

Adult dosage

  • 500 mg orally every 6 hours for 21 days


Adult dosage

  • 500 mg orally every 6 hours for 14 days

Pediatric dosage

  • 40-50 mg/kg/day orally divided every 6 hours for 14 days; not to exceed 2 g/day

Chlamydial Infection

Pediatric dosage

  • 50 mg/kg/day orally divided every 6 hours for 14 days

Streptococcal Pharyngitis, Tonsillitis

Pediatric dosage

  • 20 mg/kg/day orally divided every 12 hours

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”


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What Are Side Effects Associated with Using Erythromycin Base?

Common side effects of the Erythromycin Base include:

  • nausea,
  • vomiting,
  • diarrhea,
  • abdominal pain, and
  • loss of appetite

Serious side effects of the Erythromycin Base include:

  • upper right abdominal pain,
  • abdominal swelling,
  • nausea,
  • vomiting,
  • feeling unwell,
  • confusion,
  • drowsiness,
  • dark-colored urine,
  • clay-colored stools,
  • loss of appetite,
  • weakness,
  • itching,
  • yellowing of the skin or eyes (jaundice),
  • fever,
  • abdominal cramps,
  • dehydration,
  • watery diarrhea,
  • pus or mucus in the stool,
  • shortness of breath,
  • racing or slow heartbeat,
  • chest pain,
  • dizziness,
  • fluttering or pounding heartbeat,
  • fainting,
  • lightheadedness,
  • cold sweats,
  • low blood pressure,
  • itching,
  • swelling of the lips, eyelids, and inside the throat,
  • joint pain,
  • sudden rash appearing on the palms of the hands, soles of the feet and face,
  • rash,
  • raw and painful areas on the skin,
  • skin peeling without blistering,
  • increased urine output,
  • high blood pressure,
  • sudden weight gain,
  • abdominal pain radiating to the back,
  • abdominal pain that increases after eating,
  • elevated pulse,
  • seizures (convulsions), and
  • reversible hearing loss.

Rare side effects of the Erythromycin Base include:

  • none 

This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Erythromycin Base?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Erythromycin Base has severe interactions with the following drugs:
  • Erythromycin Base has serious interactions with at least 264 other drugs.
  • Erythromycin Base has moderate interactions with at least 283 other drugs.
  • Erythromycin Base has minor interactions with at least 40 other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Erythromycin Base?


  • 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

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Erythromycin Base?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Erythromycin Base?”


  • 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 the patient and increases the 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 the myasthenic syndrome were reported in patients receiving erythromycin therapy
  • Infantile hypertrophic pyloric stenosis (IHPS) in infants following erythromycin therapy was reported; a possible dose-response effect was 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 the 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 an appropriate penicillin regimen
    • Clostridium difficile associated diarrhea
      • Clostridium difficile associated diarrhea (CDAD) is reported with the 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 the overgrowth of C. difficile; C. difficile produces toxins A and B which contribute to the 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 the 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 the 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 a 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 the 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 the 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 the central nervous system, extremities, and other tissues

Pregnancy and Lactation

  • May be acceptable during pregnancy
  • Lactation


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