Erythromycin 333mg EC Tablets
It is used to treat or prevent bacterial infections.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Antibiotic
Pharmacologic Class
Macrolide Antibiotic
Pregnancy Category
Category B
FDA Approved
Jan 1970
DEA Schedule
Not Controlled
Overview
What is this medicine?
Erythromycin is an antibiotic used to treat various bacterial infections, such as respiratory tract infections, skin infections, and certain sexually transmitted infections. It works by stopping the growth of bacteria.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, take it exactly as directed by your doctor. Carefully read all the information provided with your prescription and follow the instructions closely. You can take this medication with or without food, unless your doctor specifies otherwise. It's essential to swallow the medication whole, without chewing, breaking, or crushing it.
Continue taking your medication as prescribed by your doctor or healthcare provider, even if you start feeling better. This will help ensure that you receive the full benefits of the treatment.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature in a dry location, avoiding the bathroom. Keep all medications in a secure place, out of the reach of children and pets. When disposing of unused or expired medications, do not flush them down the toilet or pour them down the drain unless instructed to do so by your doctor or pharmacist. Instead, check with your pharmacist for guidance on the best disposal method or explore local drug take-back programs.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Avoid taking two doses at the same time or taking extra doses, as this can increase the risk of side effects.
To get the most benefit from your medication, take it exactly as directed by your doctor. Carefully read all the information provided with your prescription and follow the instructions closely. You can take this medication with or without food, unless your doctor specifies otherwise. It's essential to swallow the medication whole, without chewing, breaking, or crushing it.
Continue taking your medication as prescribed by your doctor or healthcare provider, even if you start feeling better. This will help ensure that you receive the full benefits of the treatment.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature in a dry location, avoiding the bathroom. Keep all medications in a secure place, out of the reach of children and pets. When disposing of unused or expired medications, do not flush them down the toilet or pour them down the drain unless instructed to do so by your doctor or pharmacist. Instead, check with your pharmacist for guidance on the best disposal method or explore local drug take-back programs.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Avoid taking two doses at the same time or taking extra doses, as this can increase the risk of side effects.
Lifestyle & Tips
- Take the medication exactly as prescribed by your doctor, even if you start feeling better. Do not skip doses or stop taking it early, as this can lead to antibiotic resistance.
- Erythromycin EC tablets can usually be taken with or without food. Follow specific instructions on your prescription label.
- Avoid taking antacids containing aluminum or magnesium at the same time as erythromycin, as they can reduce its absorption. Separate doses by at least 2 hours.
- Avoid grapefruit juice while taking this medication, as it can increase the levels of erythromycin in your body.
- Inform your doctor about all other medications you are taking, including over-the-counter drugs, herbal supplements, and vitamins, as erythromycin can interact with many drugs.
Available Forms & Alternatives
Available Strengths:
- Erythromycin Ophth Oint 3.5gm
- Erythromycin 2% Gel 60gm
- Erythromycin 2% Gel 30gm
- Erythromycin Ophth Oint 1gm Sgl/use
- Erythromycin 2% Topical Soln 60ml
- Erythromycin DR 250mg Capsules
- Erythromycin Ophth Oint 1gm Sgl/use
- Erythromycin Base 250mg Tablets
- Erythromycin Base 500mg Tablets
- Erythromycin Ethyl 400mg/5ml Susp
- Erythromycin Eth 400mg Tablets
- Erythromycin 250mg DR Tablets
- Erythromycin 333mg EC Tablets
- Erythromycin 500mg EC Tablets
Dosing & Administration
Adult Dosing
Standard Dose:
333 mg every 8 hours or 500 mg every 12 hours
Dose Range:
250 - 500 mg
Condition-Specific Dosing:
mild_moderate_infections:
333 mg every 8 hours or 500 mg every 12 hours
severe_infections:
Up to 4 g/day in divided doses
streptococcal_infections:
250 mg every 6 hours or 333 mg every 8 hours for 10 days
pertussis:
500 mg every 6 hours for 14 days
legionnaires_disease:
500 mg to 1 g every 6 hours
Pediatric Dosing
Neonatal:
Not established (use with caution due to risk of infantile hypertrophic pyloric stenosis)
Infant:
30-50 mg/kg/day in divided doses every 6-8 hours (max 4 g/day)
Child:
30-50 mg/kg/day in divided doses every 6-8 hours (max 4 g/day)
Adolescent:
30-50 mg/kg/day in divided doses every 6-8 hours (max 4 g/day) or adult dose if weight appropriate
Dose Adjustments
Renal Impairment:
Mild:
No adjustment needed
Moderate:
No adjustment needed
Severe:
No adjustment needed (caution with doses >4 g/day)
Dialysis:
Not significantly removed by hemodialysis or peritoneal dialysis; no supplemental dose needed
Hepatic Impairment:
Mild:
No specific adjustment, but use with caution
Moderate:
Use with caution; consider dose reduction or increased dosing interval
Severe:
Use with caution; consider dose reduction or increased dosing interval due to primary hepatic excretion
Pharmacology
Mechanism of Action
Erythromycin binds to the 50S ribosomal subunit of susceptible bacteria, thereby inhibiting protein synthesis without affecting nucleic acid synthesis. It is generally considered bacteriostatic but may be bactericidal at high concentrations or against highly susceptible organisms.
Pharmacokinetics
Absorption:
Bioavailability:
Variable (20-60% for base, improved with EC formulations)
Tmax:
2-4 hours (for EC tablets)
FoodEffect:
EC tablets can generally be taken without regard to meals, but some formulations may recommend taking with food to reduce GI upset.
Distribution:
Vd:
0.7-0.8 L/kg
ProteinBinding:
70-90%
CnssPenetration:
Limited (poor penetration into CSF unless meninges are inflamed)
Elimination:
HalfLife:
1.5-2 hours (prolonged in hepatic impairment)
Clearance:
Not readily available as a specific rate, primarily hepatic clearance
ExcretionRoute:
Primarily biliary/fecal (90-95%), minor renal excretion (2-5%)
Unchanged:
Less than 5% (renal)
Pharmacodynamics
OnsetOfAction:
Rapid
PeakEffect:
Within 2-4 hours (plasma concentration)
DurationOfAction:
Dependent on dosing interval (typically every 6-12 hours)
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction: rash, hives, itching, red, swollen, blistered, or peeling skin (with or without fever), wheezing, tightness in the chest or throat, difficulty breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat.
Signs of liver problems: dark urine, fatigue, decreased appetite, stomach pain or upset, light-colored stools, vomiting, or yellow skin or eyes.
Signs of a severe skin reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis): red, swollen, blistered, or peeling skin (with or without fever), red or irritated eyes, or sores in the mouth, throat, nose, or eyes.
Urination problems: inability to pass urine or changes in urine output.
Severe dizziness or fainting.
Rapid heartbeat.
Abnormal heartbeat (long QT on ECG), which can be life-threatening. This risk may increase when taking other medications with this drug. Seek medical help immediately if you experience an irregular heartbeat.
Diarrhea, particularly a severe form called C. diff-associated diarrhea (CDAD), which can lead to life-threatening bowel problems. CDAD may occur during or after antibiotic treatment. Contact your doctor immediately if you experience stomach pain, cramps, or loose, watery, or bloody stools.
Hearing loss, which is rare but may be more likely if you have kidney problems or take high doses of this medication. If you experience hearing problems, such as hearing loss, contact your doctor right away.
Common Side Effects
Most people taking this medication will not experience severe side effects, but some may encounter mild or moderate side effects. If you experience any of the following, contact your doctor if they bother you or do not resolve:
Diarrhea
Stomach pain
Upset stomach
Vomiting
Decreased appetite
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction: rash, hives, itching, red, swollen, blistered, or peeling skin (with or without fever), wheezing, tightness in the chest or throat, difficulty breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat.
Signs of liver problems: dark urine, fatigue, decreased appetite, stomach pain or upset, light-colored stools, vomiting, or yellow skin or eyes.
Signs of a severe skin reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis): red, swollen, blistered, or peeling skin (with or without fever), red or irritated eyes, or sores in the mouth, throat, nose, or eyes.
Urination problems: inability to pass urine or changes in urine output.
Severe dizziness or fainting.
Rapid heartbeat.
Abnormal heartbeat (long QT on ECG), which can be life-threatening. This risk may increase when taking other medications with this drug. Seek medical help immediately if you experience an irregular heartbeat.
Diarrhea, particularly a severe form called C. diff-associated diarrhea (CDAD), which can lead to life-threatening bowel problems. CDAD may occur during or after antibiotic treatment. Contact your doctor immediately if you experience stomach pain, cramps, or loose, watery, or bloody stools.
Hearing loss, which is rare but may be more likely if you have kidney problems or take high doses of this medication. If you experience hearing problems, such as hearing loss, contact your doctor right away.
Common Side Effects
Most people taking this medication will not experience severe side effects, but some may encounter mild or moderate side effects. If you experience any of the following, contact your doctor if they bother you or do not resolve:
Diarrhea
Stomach pain
Upset stomach
Vomiting
Decreased appetite
Reporting Side Effects
This list is not exhaustive, and you may experience other side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Severe or watery diarrhea, especially if it contains blood or mucus (may be a sign of C. difficile infection)
- Yellowing of the skin or eyes (jaundice)
- Dark urine or pale stools
- Unusual tiredness or weakness
- Severe stomach pain or cramping
- Nausea or vomiting that is severe or persistent
- Hearing loss or ringing in the ears (tinnitus)
- Fast, pounding, or irregular heartbeat
- Dizziness, lightheadedness, or fainting
- Rash, itching, or hives
- Swelling of the face, lips, tongue, or throat
- Difficulty breathing or swallowing
Before Using This Medicine
Before taking this medication, it is essential to inform your doctor about the following:
Any allergies you have, including allergies to this drug, its components, or other substances. Be sure to describe the allergic reaction and its symptoms.
Certain health conditions, such as:
+ Abnormal heartbeat patterns, including a prolonged QTc interval on an electrocardiogram (ECG)
+ Slow heartbeat
+ Low potassium or magnesium levels
Other medications you are taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This is crucial because some medications, such as those used to treat mood disorders, abnormal heart rhythms, or migraine headaches, may interact with this drug and should not be taken concurrently.
It is critical to note that this is not an exhaustive list of all potential interactions. Therefore, it is vital to discuss all your medications and health conditions with your doctor and pharmacist to ensure safe use.
To guarantee your safety, always consult with your doctor before starting, stopping, or modifying the dosage of any medication. This includes verifying that it is safe to take this medication with all your other medications and health conditions.
Any allergies you have, including allergies to this drug, its components, or other substances. Be sure to describe the allergic reaction and its symptoms.
Certain health conditions, such as:
+ Abnormal heartbeat patterns, including a prolonged QTc interval on an electrocardiogram (ECG)
+ Slow heartbeat
+ Low potassium or magnesium levels
Other medications you are taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This is crucial because some medications, such as those used to treat mood disorders, abnormal heart rhythms, or migraine headaches, may interact with this drug and should not be taken concurrently.
It is critical to note that this is not an exhaustive list of all potential interactions. Therefore, it is vital to discuss all your medications and health conditions with your doctor and pharmacist to ensure safe use.
To guarantee your safety, always consult with your doctor before starting, stopping, or modifying the dosage of any medication. This includes verifying that it is safe to take this medication with all your other medications and health conditions.
Precautions & Cautions
Important Information for Patients Taking This Medication
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
If you are taking this medication long-term, your doctor may recommend regular blood tests to monitor your condition. Be sure to discuss this with your doctor.
This medication may interfere with certain laboratory tests. Therefore, it is crucial to notify all your healthcare providers and laboratory personnel that you are taking this medication.
Do not take this medication for longer than prescribed, as this may increase the risk of a second infection.
If you are following a low-sodium or sodium-free diet, consult your doctor before taking this medication, as some products may contain sodium.
If you have myasthenia gravis, discuss your condition with your doctor. If your symptoms worsen, contact your doctor immediately. Additionally, if you experience new or worsening muscle weakness, difficulty chewing or swallowing, breathing problems, droopy eyelids, or changes in vision (such as blurred vision or double vision), seek medical attention right away.
Patients 65 years or older should use this medication with caution, as they may be more susceptible to side effects.
If you are pregnant, planning to become pregnant, or breastfeeding, consult your doctor to discuss the potential benefits and risks to you and your baby.
Special Considerations for Newborns
Newborns taking this medication are at risk of developing a severe stomach problem. If your child vomits or becomes irritable during feeding, contact your doctor immediately.
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
If you are taking this medication long-term, your doctor may recommend regular blood tests to monitor your condition. Be sure to discuss this with your doctor.
This medication may interfere with certain laboratory tests. Therefore, it is crucial to notify all your healthcare providers and laboratory personnel that you are taking this medication.
Do not take this medication for longer than prescribed, as this may increase the risk of a second infection.
If you are following a low-sodium or sodium-free diet, consult your doctor before taking this medication, as some products may contain sodium.
If you have myasthenia gravis, discuss your condition with your doctor. If your symptoms worsen, contact your doctor immediately. Additionally, if you experience new or worsening muscle weakness, difficulty chewing or swallowing, breathing problems, droopy eyelids, or changes in vision (such as blurred vision or double vision), seek medical attention right away.
Patients 65 years or older should use this medication with caution, as they may be more susceptible to side effects.
If you are pregnant, planning to become pregnant, or breastfeeding, consult your doctor to discuss the potential benefits and risks to you and your baby.
Special Considerations for Newborns
Newborns taking this medication are at risk of developing a severe stomach problem. If your child vomits or becomes irritable during feeding, contact your doctor immediately.
Overdose Information
Overdose Symptoms:
- Severe nausea
- Vomiting
- Diarrhea
- Abdominal pain
- Hearing loss
- Severe liver dysfunction
- Cardiac arrhythmias (rare but possible)
What to Do:
Seek immediate medical attention or call a poison control center (1-800-222-1222). Treatment is generally supportive, including gastric lavage and general supportive measures. Hemodialysis is not effective.
Drug Interactions
Contraindicated Interactions
- Colchicine (in patients with renal or hepatic impairment)
- Ergotamine, Dihydroergotamine (risk of acute ergot toxicity)
- Lurasidone, Pimozide (risk of QT prolongation, arrhythmias)
- Lovastatin, Simvastatin (risk of rhabdomyolysis)
- Eliglustat (in patients who are CYP2D6 poor metabolizers or taking strong/moderate CYP2D6 inhibitors)
- Dronedarone, Ivabradine, Ranolazine (risk of QT prolongation)
Major Interactions
- Statins (e.g., atorvastatin, rosuvastatin - increased risk of myopathy/rhabdomyolysis)
- Warfarin (increased INR/bleeding risk)
- Carbamazepine, Phenytoin, Valproic acid (increased anticonvulsant levels)
- Theophylline (increased theophylline levels, toxicity)
- Digoxin (increased digoxin levels)
- QT-prolonging drugs (e.g., antiarrhythmics like amiodarone, sotalol; antipsychotics; tricyclic antidepressants; fluoroquinolones - increased risk of Torsades de Pointes)
- Calcium channel blockers (e.g., verapamil, diltiazem, amlodipine - increased CCB levels, hypotension, bradycardia)
- Corticosteroids (e.g., methylprednisolone - increased corticosteroid levels)
- Sildenafil, Tadalafil (increased PDE5 inhibitor levels)
- Immunosuppressants (e.g., cyclosporine, tacrolimus, sirolimus - increased immunosuppressant levels, nephrotoxicity)
- Benzodiazepines (e.g., midazolam, triazolam - increased sedation)
- Cimetidine (may increase erythromycin levels)
- Clindamycin, Lincomycin (antagonistic effect)
- Chloramphenicol (antagonistic effect)
Moderate Interactions
- Oral contraceptives (potential decreased efficacy, though evidence is weak)
- Rifampin (may decrease erythromycin levels)
- Antacids (may decrease erythromycin absorption, separate administration)
- Grapefruit juice (may increase erythromycin levels)
Minor Interactions
- Not available
Monitoring
Baseline Monitoring
Liver Function Tests (LFTs)
Rationale: To assess baseline hepatic function, especially in patients with pre-existing liver disease, as erythromycin is primarily metabolized and excreted by the liver.
Timing: Before initiating therapy, particularly for prolonged courses or in patients with hepatic impairment.
Electrolytes (Potassium, Magnesium)
Rationale: To assess baseline electrolyte status, as hypokalemia or hypomagnesemia can increase the risk of QT prolongation.
Timing: Before initiating therapy, especially in patients at risk for arrhythmias or on other QT-prolonging drugs.
ECG
Rationale: To assess baseline QT interval, especially in patients with pre-existing cardiac conditions, electrolyte imbalances, or concomitant use of other QT-prolonging drugs.
Timing: Before initiating therapy in high-risk patients.
Routine Monitoring
Liver Function Tests (LFTs)
Frequency: Periodically, especially during prolonged therapy (e.g., >2 weeks) or if signs/symptoms of hepatotoxicity develop.
Target: Within normal limits
Action Threshold: Significant elevation (e.g., >3x ULN) of transaminases or bilirubin; discontinue if cholestatic hepatitis occurs.
Signs and Symptoms of Hepatotoxicity
Frequency: Daily patient assessment
Target: Absence of symptoms
Action Threshold: Yellowing of skin/eyes, dark urine, severe abdominal pain, persistent nausea/vomiting; discontinue and investigate.
Signs and Symptoms of QT Prolongation/Arrhythmias
Frequency: Daily patient assessment, especially in high-risk patients
Target: Absence of symptoms
Action Threshold: Palpitations, dizziness, syncope; obtain ECG and discontinue if significant QT prolongation or arrhythmia is suspected.
INR (for patients on warfarin)
Frequency: More frequently (e.g., daily to every few days) after initiating erythromycin and until stable
Target: Therapeutic range for indication
Action Threshold: INR above therapeutic range; adjust warfarin dose.
Drug Levels (for co-administered drugs with narrow therapeutic index, e.g., theophylline, carbamazepine, digoxin, cyclosporine)
Frequency: As clinically indicated, especially after initiating or discontinuing erythromycin
Target: Therapeutic range for specific drug
Action Threshold: Levels outside therapeutic range; adjust dose of co-administered drug.
Symptom Monitoring
- Diarrhea (especially severe or bloody, indicative of C. difficile-associated diarrhea)
- Nausea
- Vomiting
- Abdominal pain/cramping
- Hearing loss/tinnitus (especially with high doses or renal/hepatic impairment)
- Yellowing of skin or eyes (jaundice)
- Dark urine
- Unusual tiredness or weakness
- Palpitations or irregular heartbeat
- Dizziness or lightheadedness
- Syncope (fainting)
Special Patient Groups
Pregnancy
Erythromycin is generally considered safe for use during pregnancy (Category B). It is often used as an alternative for penicillin-allergic pregnant women.
Trimester-Specific Risks:
First Trimester:
No increased risk of major birth defects observed in human studies.
Second Trimester:
No increased risk of adverse outcomes observed.
Third Trimester:
No increased risk of adverse outcomes observed.
Lactation
Erythromycin is excreted into breast milk in small amounts. It is generally considered compatible with breastfeeding (L2). Monitor the infant for gastrointestinal upset (diarrhea, candidiasis) or rash.
Infant Risk:
Low risk. Potential for mild gastrointestinal upset (diarrhea, candidiasis) in the infant.
Pediatric Use
Use with caution in neonates and young infants due to an association with infantile hypertrophic pyloric stenosis (IHPS), particularly when administered during the first 2 weeks of life. Benefits should outweigh risks. Dosing is weight-based. EC formulations may not be suitable for very young children who cannot swallow tablets.
Geriatric Use
No specific dose adjustment is typically needed based on age alone, but elderly patients may be more susceptible to adverse effects such as hearing loss (especially with high doses), QT prolongation, and drug interactions due to polypharmacy and potential age-related decline in hepatic function. Monitor closely for adverse effects and drug interactions.
Clinical Information
Clinical Pearls
- Erythromycin is a potent CYP3A4 inhibitor; thoroughly review patient's medication list for potential drug interactions, especially with narrow therapeutic index drugs or QT-prolonging agents.
- While EC formulations reduce GI upset compared to erythromycin base, gastrointestinal side effects (nausea, vomiting, abdominal cramps) are still common.
- Advise patients to complete the full course of therapy, even if symptoms improve, to prevent the development of antibiotic resistance.
- Erythromycin is a good alternative for patients with penicillin allergies, particularly for respiratory tract infections, skin infections, and atypical pneumonias.
- Monitor for signs of C. difficile-associated diarrhea (CDAD), which can occur during or even several weeks after antibiotic therapy.
- Transient hearing loss can occur, especially with high doses or in patients with renal or hepatic impairment; it is usually reversible upon discontinuation.
Alternative Therapies
- Azithromycin (another macrolide, longer half-life, less frequent dosing, fewer CYP interactions)
- Clarithromycin (another macrolide, similar spectrum, more potent CYP3A4 inhibitor than azithromycin)
- Amoxicillin/Clavulanate (for respiratory/skin infections, broader spectrum)
- Doxycycline (for atypical infections, some skin infections)
- Levofloxacin/Moxifloxacin (fluoroquinolones, broader spectrum, but with specific risks)
- Penicillin V (for streptococcal infections, if not allergic)
Cost & Coverage
Average Cost:
Varies, typically $20-$100 per 30 tablets
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (Generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea to check with your pharmacist. If you have any questions or concerns about this medication, don't hesitate to discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When seeking help, be prepared to provide detailed information about the overdose, including the medication taken, the amount, and the time it occurred.