Ery-Tab (Erythromycin) - Oral

What Is Ery-Tab?

Ery-Tab (erythromycin delayed-release tablet) is a prescription drug used to treat various bacterial infections, including respiratory infections, skin infections, diphtheria, and pertussis.

As a macrolide antibiotic, Ery-Tab stops the growth of infection-causing bacteria. It comes in a delayed-release tablet form that is enteric-coated. Enteric-coated tablets protect the medicine from being inactivated by stomach acid. This coating also allows the antibiotic to be absorbed in the small intestine.

Drug Facts

Generic Name: Erythromycin

Brand Name(s): Ery-Tab, E.E.S. 200, E.E.S. 400, E.E.S Granules, Eryc, Eryped, Eryped 200, Eryped 400, Erythrocin, Erythrocin Stearate

Administration Route(s): Oral

Drug Availability: Prescription

Therapeutic Classification: Antibiotic

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Erythromycin

Dosage Form(s): Delayed-release enteric-coated tablet

What Is Ery-Tab Used For?

Ery-Tab treats certain bacterial infections, such as:

Ery-Tab does not treat infections caused by a virus, such as the common cold, flu, or COVID-19.

Ery-Tab (Erythromycin) Drug Information - Illustration by Zoe Hansen

Verywell / Zoe Hansen

How to Take Ery-Tab

Ery-Tab is an oral medicine to be taken as a tablet by mouth.

Because the tablet is delayed release, you should swallow the tablet whole. Do not chew, crush, or dissolve the tablet.

Take your medication as prescribed by your healthcare provider. You can take Ery-Tab with or without food, but it may be absorbed better on an empty stomach (one hour before or two hours after a meal). Make sure to finish the entire course as prescribed, even if you feel better. Do not skip doses or stop taking the medicine unless your provider tells you to do so. Taking the medication the full time prescribed ensures the bacteria do not come back. 

When taking Ery-Tab, avoid grapefruit and grapefruit juice. Grapefruit can increase the levels of erythromycin in your body and cause a dangerous heart rhythm.

Read the information guide that comes with your prescription, and talk to your provider if you have any questions.


Store Ery-Tab at room temperature (68–77 degrees Fahrenheit), away from heat, direct light, and moisture. Keep it in its original labeled container and out of the reach of children and pets.

Off-Label Uses

Healthcare providers may prescribe Ery-Tab for off-label uses, meaning for conditions not specifically indicated by the FDA.

Ery-Tab can be prescribed off-label for:

  • Acne
  • Burn wound infection
  • Certain infections in people with HIV
  • Chancroid (a type of sexually transmitted ulcer)
  • Cholera (a severe diarrheal infection, usually caused by contaminated water)
  • Early Lyme disease
  • Gastroparesis (delayed stomach emptying)
  • Impetigo 
  • Prevention of pneumonia in people with sickle cell disease who are allergic to penicillin
  • Tetanus

In addition to Ery-Tab, erythromycin is available in other formulations. These include oral liquid, IV (intravenous, which means it is injected into a vein), eye drops, and topical (applied to the skin) ointment, gel, or solution. 

How Long Does Ery-Tab Take to Work?

A dose of Ery-Tab reaches the highest level in the body in one to four hours. When taking Ery-Tab, you may feel better within a few days, but do not stop taking medicine. Taking the medicine for the full length of time prescribed ensures you get better and that the bacteria do not come back.

What Are the Side Effects of Ery-Tab?

This is not a complete list of side effects and others may occur. A medical professional can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at or 800-FDA-1088.

Common Side Effects

The most common side effects of Ery-Tab are:

  • Nausea 
  • Vomiting 
  • Diarrhea 
  • Abdominal pain
  • Appetite loss
  • Rash/hives 
  • Increased levels on liver function tests
  • Jaundice (yellowing of the skin or whites of the eyes caused by liver problems)

Severe Side Effects

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Hypersensitivity reaction or anaphylaxis: Symptoms can include rash, hives, swelling around the lips, tongue, and face, and difficulty breathing
  • Stevens-Johnson syndrome, a medical emergency characterized by flu-like symptoms, red or purple rash, and blisters
  • Erythema multiforme, a skin disorder with bullseye-shaped lesions
  • Toxic epidermal necrolysis, a life-threatening skin disorder with peeling and blistering of the skin 
  • Antibiotic-associated diarrhea, which can be severe or life-threatening
  • Superinfection (a secondary infection)
  • Liver problems
  • Heart rhythm problems 
  • Hearing loss
  • Seizures
  • Inflammation of the pancreas
  • Worsening of myasthenia gravis (autoimmune disorder affecting the communication between nerves and muscles causing muscle weakness)
  • Interstitial nephritis (a kidney disorder)

Symptoms of an allergic reaction or severe skin reaction require emergency medical attention.

Call your provider right away if you have: 

  • Severe stomach pain
  • Watery or bloody diarrhea (this can occur up to several months after you stop taking erythromycin)
  • Headache
  • Chest pain
  • Dizziness
  • Fainting
  • Fast heartbeat
  • Seizure
  • Changes in hearing

Also notify your provider right away if you have symptoms of inflammation of the pancreas, such as severe pain in the upper stomach or nausea and vomiting), or liver problems.

Symptoms of liver problems can include:

  • Appetite loss
  • Stomach pain
  • Fatigue
  • Easy bruising or bleeding
  • Dark urine
  • Clay-colored stools
  • Jaundice

Long-Term Side Effects

Since Ery-Tab is only taken for a short period in many cases, most people only experience mild side effects like stomach upset and diarrhea. However, some people take erythromycin for a longer period. In these cases, there is a greater likelihood of long-term side effects.

In rare cases, Ery-Tab can cause liver problems or liver failure. People who take erythromycin for an extended period will have regular liver function test monitoring.

There is also a possibility of QT prolongation, which is a heart rhythm disorder that can be serious or cause death. People who have heart conditions, take medications for heart rhythm problems, or take other drugs that interact with erythromycin are at higher risk for QT prolongation.

As with any antibiotics, Ery-Tab can cause diarrhea which can be serious or life-threatening. Diarrhea can even occur months after stopping the antibiotic. Report diarrhea to your provider immediately. Seek emergency medical care for severe diarrhea, especially if it is watery or bloody.

Report Side Effects

Ery-Tab may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Ery-Tab Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage forms (granules for suspension, suspension, and tablets):
    • For treatment of bacterial infections:
      • Adults—400 milligrams (mg) every 6 hours or 800 mg every 12 hours. Depending on the severity of your infection, your doctor may increase your dose as needed up to 4000 mg per day.
      • Children—Dose is based on body weight and must be determined by your doctor. The dose is usually 30 to 50 milligrams (mg) per kilogram (kg) of body weight per day, divided in equal doses and taken every 6 hours. Depending on the severity of your infection, your doctor may increase your dose as needed.
  • For oral dosage form (PCE® tablets):
    • For prevention of recurring attacks of rheumatic fever:
      • Adults—250 milligrams (mg) 2 times a day.
      • Children—Use and dose must be determined by your doctor.
    • For treatment of bacterial infections:
      • Adults—333 milligrams (mg) every 8 hours or 500 mg every 12 hours. Depending on the severity of your infection, your doctor may increase your dose as needed up to 4000 mg per day.
      • Children—Dose is based on body weight and must be determined by your doctor. The dose is usually 30 to 50 milligrams (mg) per kilogram (kg) of body weight per day, divided in equal doses. Depending on the severity of your infection, your doctor may increase your dose as needed.


In some cases, certain people may require modifications to their Ery-Tab regimen.


Children can take erythromycin. However, healthcare providers more commonly prescribe children the oral suspension.

Pregnancy or Breastfeeding

People who are pregnant or planning to become pregnant should consult their healthcare provider before taking Ery-Tab. People who are breastfeeding should also ask their provider before taking Ery-Tab.

Older Adults

In adults who are 65 years or older, there are a few precautions with Ery-Tab.

Older adults, especially those with kidney or liver problems, are at higher risk for hearing loss due to erythromycin. Older adults may also be more likely to develop heart rhythm problems.

Older adults who take blood thinners may experience an increased blood thinner effect while taking Ery-Tab, making them more likely to bleed. Also, because Ery-Tab contains some sodium in the tablet, older adults with certain conditions (such as heart failure) may have trouble eliminating the sodium in the urine. Adults who are 65 and older should consult their provider before taking Ery-Tab.

Liver Problems

Ery-Tab should be used with caution in people with liver problems.

Missed Dose

If you miss a dose of Ery-Tab, take it as soon as possible. If it is almost time for the next dose, skip the missed dose. Do not take two doses together.

Overdose: What Happens If I Take Too Much Ery-Tab?

Do not take more erythromycin than prescribed by a healthcare provider. Seek emergency medical attention if you think you have overdosed on this medication.

What Happens If I Overdose on Ery-Tab?

If you think you or someone else may have overdosed on Ery-Tab, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Ery-Tab, call 911 immediately.


Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check you or your child's progress at regular visits to make sure this medicine is working properly and to check for unwanted effects. If your or your child's symptoms do not improve within a few days, or if they become worse, check with your doctor.

Do not use this medicine if you or your child are also using astemizole (Hismanal®), cisapride (Propulsid®), ergotamine (Cafergot®, Ergomar®), dihydroergotamine (Migranal®), pimozide (Orap®), terfenadine (Seldane®), or statin medicine (eg, lovastatin, simvastatin, Mevacor®, Zocor®). Using these medicines together may increase risk for more serious side effects.

Check with your doctor right away if you or your child have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, unusual tiredness or weakness, or yellow eyes or skin. These could be symptoms of a serious liver problem.

This medicine can cause changes in heart rhythms, such as a condition called QT prolongation. It may change the way your heart beats and cause fainting or serious side effects in some patients. Contact your doctor right away if you or your child have worsening symptoms of heart rhythm problems, such as fast, pounding, or uneven heartbeat.

Make sure your doctor knows if you are pregnant or may be pregnant before using this medicine.

Erythromycin may cause diarrhea, and in some cases it can be severe. It may occur 2 months or more after you stop using this medicine. Do not take any medicine to treat diarrhea without first checking with your doctor. Diarrhea medicines may make the diarrhea worse or make it last longer. If you have any questions about this or if mild diarrhea continues or gets worse, check with your doctor.

Before you have any medical tests, tell the medical doctor in charge that you or your child are using this medicine. The results of some tests may be affected by this medicine.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Take Ery-Tab?

Ery-Tab is not appropriate for everyone. You should not take Ery-Tab if you are allergic to erythromycin or any of the inactive ingredients in Ery-Tab, or any macrolide antibiotics such as Zithromax (azithromycin) or Biaxin (clarithromycin).

Other reasons you may not be prescribed Ery-Tab include:

  • QT prolongation (a heart rhythm disorder) or a history of QT prolongation
  • Low potassium or low magnesium levels
  • Slow heart rate 
  • Recent heart attack
  • Cardiomyopathy (a disease of the heart muscle)
  • If you take certain other drugs, including Orap (pimozide); Belcomp-PB, Cafatine PB, Micomp-PB, and Ergocomp-PB (ergotamine); Migranal and D.H.E. 45 (dihydroergotamine); Altoprev and Mevacor (lovastatin); or Zocor (simvastatin)

Ery-Tab can be used with caution in:

  • Older adults
  • People with kidney or liver problems
  • People with myasthenia gravis
  • Recent antibiotic-associated colitis (severe diarrhea caused by antibiotics)

What Other Medications Interact With Ery-Tab?

Before taking Ery-Tab, tell your healthcare provider about all your medicines, including prescription and over-the-counter (OTC) medicines, and vitamins or supplements. Your provider can advise you on any possible drug interactions. The list below includes some of the drugs that interact with erythromycin:

  • Alprazolam (brands include Xanax)
  • Amlodipine (brands include Caduet and Consensi)
  • Bromocriptine (brands include Cycloset and Parlodel)
  • Carbamazepine (brands include Tegretol)
  • Cilostazol (brands include Pletal)
  • Colchicine (brands include Colcyrs and Mitigare)
  • Cyclosporine (brands include Gengraf and Sandimmune)
  • Digoxin (brands include Digox and Lanoxin)
  • Diltiazem (brands include Cardizem)
  • Ergotamine/dihydroergotamine (brands include D.H.E. 45 and Migranal)
  • Fluconazole (brands include Diflucan)
  • Midazolam (brands include Versed)
  • Phenytoin (brands include Dilantin)
  • Pimozide (brands include Orap)
  • Posaconazole (brands include Noxafil and Posanol)
  • Procainamide (brands include Pronestyl)
  • Quinidine (brands include Cardioquin and Cin-Quin)
  • Saquinavir (brands include Invirase)
  • Sildenafil (brands include Viagra and Revatio)
  • Sotalol (Betapace and Sorine)
  • Statins (e.g., lovastatin such as the brands Altoprev or Mevacor and simvastatin such as Zocor)
  • Theophylline (brands include Theo 24, Theochron)
  • Thioridazine (brands include Mellaril or Melleril)
  • Triazolam (brands include Halcion)
  • Valproic acid (brands include Belvo and Depakote)
  • Verapamil (brands include Verapamil)
  • Warfarin (brands include Coumadin and Jantoven)

In addition to these medications, other drugs interact with erythromycin, too. This is not a full list of drug interactions. Consult your healthcare provider for a full list of drug interactions.

What Medications Are Similar?

Ery-Tab is a macrolide antibiotic. Other macrolide antibiotics include:

  • Biaxin (clarithromycin)
  • Dificid (fidaxomicin): This is a macrolide antibiotic but it is only used to treat antibiotic-related diarrhea
  • Zithromax (azithromycin)

There are many other classes of antibiotics, which are used for various bacterial infections.

Some common classes of antibiotics and examples of drugs in each class include:

  • Cephalosporin antibiotics: Omnicef (cefdinir), Keflex (cephalexin), Ceftin (cefuroxime)
  • Lincosamide antibiotics: Clindamycin
  • Penicillin antibiotics: Augmentin (amoxicillin and clavulanic acid), penicillin, and amoxicillin
  • Quinolone antibiotics: Levofloxacin and ciprofloxacin
  • Sulfa antibiotics: Bactrim (trimethoprim/sulfamethoxazole)
  • Tetracycline antibiotics: Doxycycline, minocycline, and tetracycline

There are also topical, OTC antibiotics, such as Neosporin and bacitracin. Your healthcare provider will select an antibiotic based on what will be effective against the bacteria causing your infection.

This is a list of drugs also prescribed for bacterial infections. It is not a list of drugs recommended to take with erythromycin. Ask your healthcare practitioner if you have questions.

Frequently Asked Questions

  • What is Ery-Tab used for?

    Ery-Tab is an antibiotic. It contains the ingredient erythromycin. Ery-Tab treats certain bacterial infections, such as bronchitis, pneumonia, Legionnaires’ disease, whooping cough, and more. Ery-Tab only works against bacterial infections. It does not treat viral infections like the flu, cold, or COVID-19.

  • How does Ery-Tab work?

    Erythromycin works by killing bacteria and preventing their growth.

  • What drugs should not be taken with Ery-Tab?

    Many drugs can possibly interact with Ery-Tab. Some of these drugs include Viagra (sildenafil), Xanax (alprazolam), statins such as lovastatin or simvastatin, calcium channel blockers such as amlodipine, verapamil, or diltiazem, and digoxin.

    Talk to your healthcare provider about all of the medications you take before starting Ery-Tab.

  • How long does it take for Ery-Tab to work?

    A single dose of Ery-Tab reaches its highest levels between one to four hours. You may start to feel better several days after you start taking Ery-Tab. Although you may feel better, it’s important to finish the full course of antibiotics prescribed to make sure the infection completely clears up.

  • How do I stop taking Ery-Tab?

    Your healthcare provider will advise you on how long to take Ery-Tab. When you finish your last dose of Ery-Tab, you can stop taking it. There is no need to taper off of this drug.

How Can I Stay Healthy While Taking Ery-Tab?

Before taking Ery-Tab, discuss all medical conditions and medical history with your healthcare provider, including your medication use. Erythromycin can interact with many different medications, so telling your provider this information helps ensure that Ery-Tab will be prescribed safely. Do not consume grapefruit or grapefruit juice when taking Ery-Tab. 

While taking Ery-Tab, it is important to remember that erythromycin is an antibiotic. You must take antibiotics for the full length of time prescribed. If you stop taking the antibiotic too soon, the infection could come back, or the bacteria may become resistant to the medication. If this happens, the treatment might not work as well next time you need it.

However, there are times when you might not be able to take the medicine due to serious side effects. So, if you are taking Ery-Tab and you notice any concerning symptoms, call your provider or get emergency medical attention if needed. In these cases, your provider may tell you to stop taking Ery-Tab and take a different antibiotic instead. Always check with a medical professional if you have any concerns or questions.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare professional. Consult your doctor before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. U.S. National Library of Medicine. Medline Plus. Erythromycin.

  2. U.S. National Library of Medicine. DailyMed. Ery-Tab.

  3. Epocrates. Ery-Tab.

  4. Prescriber’s Digital Reference. Ery-Tab.

  5. Farzam K, Nessel TA, Quick J. StatPearls. Erythromycin.

By Karen Berger, PharmD
Karen Berger, PharmD, is a community pharmacist and medical writer/reviewer.