Difference Between Erythromycin and Clarithromycin (With Table)

Erythromycin and Clarithromycin are both types of macrolide antibiotics that are used for treating soft tissue infections, infections of the respiratory tract, urinary tract, chest, etc. One antibiotic is considered as a derivative of the latter and better in tolerance. Though being the derivative of others and treating the same kind of infections, the difference arises in the way the drug affects the body and the action against the bacteria.

Erythromycin v/s Clarithromycin 

The main difference between Erythromycin and Clarithromycin is that erythromycin is a type of antibiotic that is used for treating infections that are caused by bacteria, which is Gram-positive, and other infections of the chest, ears, skin, etc. On the other hand, Clarithromycin is an antibiotic pill that is used for treating chest diseases or infections like pneumonia, skin problems like cellulitis, infections of ears, and stomach ulcers.

Erythromycin is an antibiotic medicine used for treating many bacterial infections or diseases like infections of the respiratory tract, skin, Chlamydia, pelvic inflammatory disease, and syphilis. While pregnancy, this drug is also given to the pregnant woman to prevent the newborn from the Group B streptococcal infection and also helps in improving gastroparesis.

The Clarithromycin pill is used to treat numerous infections caused by bacteria and even prevent that infection beforehand. Clarithromycin is also sometimes combined with anti-ulcer medicines for treating some specific stomach ulcers. The other name for Clarithromycin is a macrolide antibiotic that helps to prevent the bacteria from spreading to other parts of the body.

Comparison Table Between Erythromycin and Clarithromycin

Parameters of Comparison




Poor coverage of H.flu and MSSA.

Better coverage of H.flu and MSSA.

How it is administered

It is usually taken 4 times a day i.e. every six hours

It is usually taken 3 times a day i.e. every 8 hours.


This medicine concentrates in the liver and then gets transferred to bile.

This medicine is largely distributed in tissues and fluids.

Food consumption

It affects the absorption of the medicine.

It does not affect the absorption of the medicine.

Intravenous form

Erythromycin can be taken in intravenous form.

Clarithromycin is not recommended to be taken in intravenous form.


Erythromycin drugs are usually recommended during pregnancy.

Clarithromycin drugs can cause miscarriage and hence not recommended.

What is Erythromycin?

Erythromycin is a drug that is used for treating bacterial infections like respiratory tract infections which includes bronchitis, pneumonia, legionnaires disease which is the infection of lungs, and pertussis which is an infection causing severe coughing, diphtheria which is throat infection, STDs like syphilis and infections of ears, urinary tract, and skin.

Erythromycin also helps to treat recurrent rheumatic fever. Erythromycin falls under the medication class called macrolide antibiotics that works as an agent that stops the bacteria from growing. Antibiotics like erythromycin do not help to treat colds, flu, and other viral infections. When you take an antibiotic when it is not prescribed, it increases the chance of getting infected later on which will oppose the treatment using antibiotics. Erythromycin comes in a form of a delayed-release capsule, regular capsule, delayed-release tablet, regular tablet, and also oral suspension medicine.

Erythromycin can be taken with or without food every 6 hours which means 4 times a day, every 8 hours that is 3 times a day, or 12 hours means twice a day. This antibiotic is also used to prevent the infection of the heart in people who are suffering from dental and other procedures. Taking erythromycin also comes with some side effects like itchy rashes, hives, difficulty while breathing or swallowing food or water, feeling lethargic, dark-colored urine, seizures, serious diarrhea, etc.

What is Clarithromycin?

Clarithromycin is also a macrolide antibiotic that fights infections in the body. Clarithromycin treats many kinds of bacterial infections that affect the skin and respiratory system. Other than that, it is also combined with other medicines to treat patients suffering from stomach ulcers that are caused by Helicobacter pylori. Just like erythromycin, clarithromycin also does not work for common colds and flu and it is recommended to take the medicine till the prescription date or it can cause infections in the future which will resist the treatment by antibiotic drugs.

Certain medications are not suitable for patients with some specific conditions which is why it is important to inform your doctor before taking clarithromycin. The conditions for clarithromycin are pregnancy or breastfeeding, problems in the working of liver and kidney, heart problems, myasthenia gravis if you are having a statin medicine that is for high cholesterol and allergic to this medicine. Clarithromycin should be taken exactly as your doctor prescribed you.

Many types of clarithromycin tablets are recommended to take two times a day that is in the morning and evening. If the tablet prescribed to you is a modified release tablet, then taking one dose a day is enough as the benefits of these tablets release slowly throughout the day. Other types of clarithromycin like standard release tablets or liquid medicine and sachets are taken before or after eating. When a clarithromycin tablet is prescribed for a child, the dosage depends on the weight of the child. The course of this antibiotic can last from 5 to 14 days. Even though you feel that you got rid of the infections, you should not stop the medication unless your doctor tells you to.

Main Differences Between Erythromycin and Clarithromycin

  1. Erythromycin is an antibiotic drug that is prescribed to be taken every 6 hours a day. On the other hand, clarithromycin is also an antibiotic drug that is prescribed to be taken every 8 hours a day.
  2. If erythromycin is taken after eating food, the benefits of the medicine spread slower while the food consumption does not affect the benefits of the clarithromycin drug. 
  3. Erythromycin can be taken through intravenous form whereas, clarithromycin should not be taken through the intravenous form.
  4. Erythromycin provides bad coverage of H.flu and MSSA whereas, clarithromycin provides better coverage of H.flu and MSSA than erythromycin.
  5. When women get pregnant, their doctors usually allow them to take erythromycin whereas, clarithromycin is strictly not recommended during pregnancy as it can cause miscarriage or may harm the baby in the womb.


In conclusion, the antibiotics Erythromycin and Clarithromycin are used to treat diseases and infections caused by bacteria and do not cure common fever, flu, and cold. Clarithromycin is a derivative of erythromycin that provides better tolerance and better tissue penetration compared to erythromycin.

The good thing about Clarithromycin is that the benefits of this medicine do not depend on the consumption of food. It works properly even if you take the medicine before and works the same after eating. While the erythromycin medicinal properties slow down when the food is being consumed before taking it. But during pregnancy, clarithromycin is not recommended as it increases the chances of miscarriage, while erythromycin is usually prescribed as no scientific reasons are available that state that it harms the unborn baby.


  1. https://link.springer.com/article/10.1023/A:1027309703313
  2. https://www.sciencedirect.com/science/article/pii/S0149291896801792