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Omeprazole vs Pepcid (Famotidine) – Comparison of Uses & Side Effects

Omeprazole vs Pepcid (Famotidine)


Acid reflux is a common condition that features a burning pain, known as heartburn, in the lower chest area. Acid reflux occurs when there is acid backflow from the stomach into the esophagus.

Here is a comparison of two medicines that are prescribed for acid reflux:


It is a proton pump inhibitor that reduces the amount of acid produced in the stomach. By decreasing the amount of acid, this medicine can help to reduce the symptoms of acid reflux disease, like heartburn.

Omeprazole is found by the following brand names – Zegerid, Prilosec, and Losec.


The active ingredient in Pepcid is called famotidine, a histamine H2-receptor antagonist that inhibits the action of histamine on the cells, hence, reducing the production of acid.



It is used in conditions where the inhibition of gastric acid secretion may be beneficial, including:

  • the Zollinger–Ellison syndrome;
  • peptic ulcer disease;
  • gastroesophageal reflux disease;
  • dyspepsia;
  • aspiration syndromes.

In addition, it may be given together with antibiotics to treat gastric ulcers caused by infection with H. pylori.


It treats the following conditions:

  • conditions where the stomach makes too much acid, such as the Zollinger-Ellison syndrome;
  • stomach ulcers;
  • duodenal ulcer – it is  usually caused by an infection;
  • acid-related damage to the lining of the esophagus;
  • gastroesophageal reflux disease – it happens when acid in the stomach backs up into your esophagus. This may lead to a sour taste in the mouth, a burning feeling in the throat or chest, or burping.

Mechanism of Action

Omeprazole works by inhibiting the secretion of gastric acid by irreversibly blocking the enzyme system of hydrogen/potassium ATP.

Pepcid works by blocking the histamine 2 receptor in the stomach. By blocking this receptor, the histamine H2-receptor antagonist lowers the amount of acid released in the stomach.

Side Effects


The most common adverse events include:headache

  • headache;
  • diarrhea;
  • excessive gas;
  • vomiting;
  • nausea;
  • stomach pain.

Serious side effects include:

  • seizure (convulsions);
  • diarrhea which is watery or bloody;
  • fast heartbeats;
  • severe stomach pain;
  • numbness;
  • joint pain;
  • muscle cramps;
  • a rash;
  • twitching;
  • tremors;
  • unusual pain in your thigh, hip, wrist, or back;
  • feeling irritable;
  • confusion;
  • drowsiness;
  • rapid weight gain;
  • blood in your urine;
  • urinating more or less than usual.

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The most common adverse events include:

  • vomiting;
  • constipation;
  • nausea;
  • diarrhea;
  • muscle pain;
  • fatigue;
  • insomnia;
  • headache.

Serious side effects include:

  • rash;
  • anemia;
  • yellowing of the skin or eyes (jaundice);
  • confusion;
  • visual changes;
  • irregular heartbeat;
  • hallucinations;
  • depression;
  • hair loss;
  • easy bruising or bleeding.

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For gastroesophageal reflux disease, the usual initial recommended dose of omeprazole is 20 mg orally once per day before a meal for 4 to 8 weeks. If needed, the dose may be increased to 40 mg a day.

For gastroesophageal reflux disease, the usual initial recommended dose of Pepcid is 20 mg orally once per day for up to 6 weeks.

Warnings & Precautions


There is a strong association between omeprazole and an increased risk of heart problems, according to a report done by the US Food and Drug Administration.

Moreover, taking a proton pump inhibitor, particularly over a period of more than 12 months, may increase your risk of fracture in the wrist, hip, or spine.


Recent research has concluded that this medication can have adverse effects on the central nervous system in individuals who have moderate to severe kidney problems. Therefore, if you have kidney problems, it is best to avoid this medication.

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Drug Interactionsdrugs


It may interact in a negative way with the following medications:

  • aspirin;
  • Xanax (alprazolam);
  • Cipro (an antibiotic that belongs to the family of medications known as quinolones);
  • Plavix (clopidogrel);
  • Cymbalta (duloxetine);
  • duloxetine (a selective serotonin and norepinephrine reuptake inhibitor antidepressant).


It may interact in a negative way with the following medications:

  • Advil (ibuprofen);
  • Zoloft (sertraline);
  • albuterol (a bronchodilator that relaxes muscles in the airways);
  • Cipro (ciprofloxacin);
  • Zofran (ondansetron);
  • ketoconazole (Nizoral, Extina, Kuric);
  • itraconazole (an antifungal medication that fights infections caused by fungus).


Avoid drinking alcoholic beverages while taking these medicines, as they may be damaging to the stomach.

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Is It Safe During Pregnancy or Breastfeeding?pregnant woman


This medication is excreted in breast milk, but it’s not likely to influence the breastfed baby when therapeutic doses are used. However, there are no conclusive studies regarding the safe use of this proton pump inhibitor during pregnancy.


There isn’t enough information about the safety of using this histamine H2-receptor antagonist during pregnancy. Please always consult with your healthcare professional to weigh the potential benefits and risks before taking this medicine.

It is secreted into breast milk. Due to the potential but unknown harm that this histamine H2-receptor antagonist might cause to the breastfed infant, nursing mothers should consider discontinuing the use of this medicine.

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Bottom Line – Omeprazole vs Pepcid (Famotidine)

Omeprazole is a proton pump inhibitor that reduces the amount of acid the stomach produces, hence, it allows the stomach and esophagus to heal to some degree.

Pepcid (famotidine) is an oral drug that belongs to a family of drugs called H2 blockers. It works by blocking the production of acid by acid-producing cells in the stomach. It is available as both prescription medicine and over-the-counter medicine.

According to a 2005 study done at the Department of Gastroenterology, Osaka, Japan, omeprazole is more effective than Pepcid for the control of gastro-oesophageal reflux disease symptoms in Helicobacter pylori-negative sufferers.

Furthermore, as per a 2007 study done at the University of Oklahoma Health Sciences Center, USA, gastric acid suppression in the omeprazole group over 14 days was comparable with the Pepcid group on day 1, and superior thereafter.

In conclusion, omeprazole has slightly greater efficacy in promoting ulcer healing in humans than Pepcid.

Images source – Shutterstock

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