Omeprazole vs Esomeprazole: What’s the Difference?

Published August 1st, 2020 by Bridget Reed
Fact Checked by
Camille Freking
Updated Date: Apr 12th, 2022

According to the International Foundation for Gastrointestinal Disorders, an estimated 15 to 30 percent of Americans suffer from gastroesophageal reflux disease, or GERD.

People who have GERD experience heartburn or indigestion at least twice per week over an extended period of time. Rates of GERD are increasing rapidly in the United States, and it is believed that a combination of factors, including the rising obesity rate, are influencing the increase.

Lifestyle changes and antacid medications can go a long way towards reducing the symptoms of GERD for many people, but those with more severe or more persistent GERD may need to try a different kind of medication to treat their symptoms.

Lansoprazole, Rabeprazole, Pantoprazole, Omeprazole and esomeprazole are some of the most popular drugs on the market for the treatment of GERD, but when comparing omeprazole vs. esomeprazole specifically, which is better?  

Omeprazole vs Esomeprazole Drug Class

Omeprazole, sold under the brand name Prilosec, and esomeprazole, sold under the brand name Nexium, both belong to a class of medications called proton pump inhibitors (PPIs). Although the medications work in a similar way, their chemical compositions are slightly different.

Omeprazole contains two isomers (chemical compounds that have the same formula but differ in the arrangement of their atoms) of omeprazole, while esomeprazole contains one. Although originally available only by prescription, today, both medications are available for purchase over the counter at lower strengths and by prescription at higher strengths. Omeprazole and esomeprazole are two of the most commonly prescribed PPIs on the market today. 

Omeprazole vs Esomeprazole Conditions Treated

Omeprazole and esomeprazole both treat similar conditions, including GERD, Zollinger-Ellison Syndrome, stomach ulcers, duodenal ulcers, erosive esophagitis, and other digestive conditions. 

Symptoms of Gastroesophageal Reflux Disease 

Gastroesophageal reflux disease, also known as GERD or heartburn, is a condition in which erosive gastric acid and digestive enzymes flow backwards into the esophagus from the stomach. While most people occasionally experience heartburn or acid reflux, people with GERD have these symptoms several times per week over an extended period of time.

People with GERD often have esophageal sphincters that do not function properly; the esophageal sphincter is a muscular ring that prevents food and acid from coming back up into the esophagus. If the esophageal sphincter does not seal properly and remains relaxed between swallows, food and digestive juices are able to enter the esophagus.

When acid flows from the stomach into the esophagus, it can cause serious damage, including narrowing, development of open sores, inflammation, or a condition called Barrett’s esophagus, which has an increased risk of esophageal cancer. People with GERD often experience some or all of the following symptoms:

  • Difficulty swallowing
  • Hoarseness
  • Tightness in the chest or upper abdomen
  • Regurgitation
  • Nausea
  • Sore throat
  • A repeated sour or bitter taste in the mouth
  • Sharp or burning pain behind the breast bone
  • Coughing, wheezing or needing to clear your throat

Zollinger-Ellison Syndrome

Zollinger-Ellison syndrome is a condition in which tumors form in the pancreas or upper small intestines. These tumors secrete large amounts of a hormone called gastrin, which is responsible for the production of acid in the stomach. The high levels of gastrin in the body causes the stomach to overproduce acid, which can cause peptic ulcers, diarrhea, and other symptoms.  Zollinger-Ellison syndrome can be diagnosed at any time in life, but most people are diagnosed between the ages of 20 and 50. Symptoms associated with Zollinger-Ellison syndrome include:

  • Bleeding in the digestive tract
  • Abdominal pain
  • Diarrhea
  • Acid reflux and heartburn
  • Nausea and vomiting
  • Burning, aching, or discomfort in the upper abdomen
  • Decreased appetite

How Omeprazole & Esomeprazole Works

Proton pump inhibitors work by acting on the enzymes found in the parietal cells of the stomach, which are known as proton pumps. The proton pumps are responsible for the production of  hydrochloric acid, which is the primary component of stomach acid.

As the name suggests, proton pump inhibitors like omeprazole and esomeprazole inhibit the acid production of proton pumps, which helps to bring the level of acid down and prevent the creation of excess acid. First introduced in 1981, proton pump inhibitors are considered the most effective class of medications for reducing stomach acid.

Omeprazole vs Esomeprazole Dosing

Whether taking omeprazole or esomeprazole, most adults will take between 20 to 40 mg once or twice daily for control of symptoms associated with GERD and other digestive conditions. 

Omeprazole can be purchased over the counter in the form of 20 mg strength delayed-release tablets, but it can also be purchased by prescription in the form of delayed-release capsules and suspension at higher strengths.

Esomeprazole can be purchased over the counter in tablets, capsules, and mini capsules at 20 mg strength; the medication can be purchased by prescription in the form of delayed-release capsules, suspension, packets, and injections at higher strengths.

The recommended dosing instructions for omeprazole indicate that the medication can be taken anywhere from ten days to eight weeks, while esomeprazole is recommended for a period of use ranging from ten days to six months. Patients with chronic GERD or another chronic condition may take the medications for much longer periods of time. 


Long term usage of proton pump inhibitors like omeprazole and esomeprazole is associated with certain risks. Using PPIs for a longer period of time than is indicated on the dosing instructions may increase the risk of developing the following conditions:

  • Bacterial inflammation of the colon (Clostridium difficile-associated diarrhea)
  • Bone weakening conditions, such as osteoporosis. Postmenopausal women can experience bone fractures in the spine and wrist, particularly when the medication is taken for a year or more at a high dose
  • Cutaneous lupus erythematosus (CLE) and systemic lupus erythematosus (SLE) 
  • Fundic gland polyps
  • Pneumonia
  • Nutritional deficiencies, such as vitamin B-12 and magnesium deficiencies
  • Kidney disease and other problems

Some people are more likely to experience issues resulting from the long term use of PPIs than others. Risk factors include:

  • History of liver disease
  • History of low magnesium levels
  • Being of Asian descent, because the body may require more time to process PPIs, thereby requiring a lower dose
  • Being pregnant or planning to become pregnant
  • Breastfeeding

Side Effects

Neither omeprazole or esomeprazole is likely to cause side effects; however, esomeprazole is slightly more likely to produce side effects than omeprazole. Common side effects associated with both medications include:

  • Nausea
  • Vomiting
  • Diarrhea
  • Increased risk of heart attack
  • Headache

Drug Interactions

Certain drugs and supplements should not be taken with either esomeprazole or omeprazole. These medications include:

  • St. John’s wort
  • Delavirdine
  • Clopidogrel
  • Nelfinavir
  • Rilpivirine
  • Rifampin
  • Risedronate

Certain medications may interact with esomeprazole or omeprazole but can be taken with them under specific conditions. Make sure to tell your doctor or pharmacist if you are taking any of the following medications:

  • Bosentan
  • Cilostazol
  • Amphetamine
  • Atazanavir
  • Mesalamine
  • Methylphenidate
  • Antifungal drugs
  • Iron
  • Voriconazole
  • Aripiprazole
  • Bisphosphonates
  • Carvedilol
  • Raltegravir
  • Tacrolimus
  • Fosphenytoin
  • Hydrocodone
  • Methotrexate
  • Clozapine
  • Dextroamphetamine
  • Citalopram
  • Cyclosporine
  • Escitalopram
  • Phenytoin
  • Saquinavir
  • Warfarin or other vitamin K antagonists

Use in Pregnant and Breastfeeding Women


Omeprazole is categorized by the FDA as a Category C medication for pregnant women; Class C medications have not been conclusively studied regarding their effects on developing fetuses. It is recommended that women speak to their doctors about omeprazole to determine if the benefit of taking the medication during pregnancy outweighs the risks.

Although PPIs like omeprazole do pass through breast milk, no negative side effects have been demonstrated; therefore, omeprazole is generally considered safe to use while breastfeeding. Some infants take omeprazole to help with acid reflux, and the amount that these infants receive is actually greater than the amount that passes through the breast milk. 


Esomeprazole has been more conclusively studied for its effects on pregnant women than omeprazole and is considered an FDA Class B medication for pregnant women. Class B medications receive this categorization because no harm has been shown to occur to an unborn child when the medication is taken during pregnancy.

Nonetheless, each woman should consult with her doctor before taking new medications during pregnancy. No studies have been conducted regarding the safety of esomeprazole as it relates to breastfeeding, but because of the similarities between esomeprazole and omeprazole, the medication is considered safe to use while breastfeeding. 

References and Sources: 

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