Famotidine vs. Omeprazole


Various medications are available for patients suffering from acid reflux and other related gastrointestinal issues. Acid reflux occurs when the esophagus sphincter muscle that connects to the stomach malfunctions and starts relaxing at the wrong time, allowing the stomach acid to move upwards into the esophagus [1]. This causes heartburn and can damage the internal tissue of the esophagus as it does not have mucosal protection against the acid.

Famotidine and Omeprazole are two of the most popular options to treat acid reflux. Famotidine and Omeprazole work by inhibiting or halting the production of stomach acid, relieving symptoms caused by the medical condition. While both effectively reduce acid reflux symptoms, they work in slightly different ways and have different potential side effects.

About Famotidine and Omeprazole

What is Famotidine?

Famotidine (also called Pepcid AC) is a histamine-2 (H2) blocker often prescribed for patients suffering from GERD or similar gastrointestinal conditions that cause increased acid production or the movement of stomach acid to the esophageal tract. Famotidine, molecular formula C8H15N7O2S3 was approved by the FDA in 1998 to treat stomach ulcers [2].

What Conditions is Famotidine Approved to Treat?

Famotidine is a medication that belongs to a class of drugs known as H2 blockers. It works by reducing the amount of acid the stomach produces, which can help relieve symptoms like heartburn, indigestion, and acid reflux. Famotidine is commonly used to treat conditions like gastroesophageal reflux disease (GERD), stomach ulcers, and Zollinger-Ellison syndrome, a rare condition that causes the stomach to produce too much acid [3].

How Does Famotidine Work For GERD??

Famotidine works as a histamine blocker by antagonistically working on the H2 receptor. Histamine is a hormone that stimulates acid production by activating the parietal cells in the stomach tissue. Once activated, the parietal cells activate the proton pumps, which results in stomach acid secretion [4]. Famotidine acts as a bouncer of the parietal club, not allowing histamine to enter and interact with the H2 receptor [5].

Since histamine no longer interacts with the H2 receptor, the proton pump cannot be activated, causing a decrease in the production and secretion of stomach acid. By doing so, Famotidine successfully prevents stomach acid secretion and stimulation by different acid-inducing food, such as caffeine [6].

What is Omeprazole?

Omeprazole is an oral medication that belongs to a class of drugs known as Proton Pump Inhibitors (PPI) [7]. Omeprazole reduces the amount of acid the stomach produces, which can help treat conditions like gastroesophageal reflux disease (GERD), stomach ulcers, and heartburn. Omeprazole, chemical formula C17H19N3O3S received approval from the FDA to treat gastric conditions in 1989 [8].

What Conditions is Omeprazole Approved to Treat?

As a PPI, Omeprazole works by blocking the enzyme that produces acid in the stomach. Like Famotidine, Omeprazole treats conditions like GERD, stomach ulcers, hypersecretion of stomach acid, and similar gastrointestinal problems [9]. It can also prevent ulcers from forming in people who take nonsteroidal anti-inflammatory drugs (NSAIDs) regularly.

How Does Omeprazole Work For GERD?

The secretion of stomach acid is regulated primarily by the proton pumps (H+ and K+), and increased activation of these pumps can cause increased production of stomach acid [10]. ATPase, an enzyme in the parietal cell membrane, controls the activation of these pumps. Think of it as if the body hired the ATPase to turn on the machine that pumps acid into the stomach.

Now, think of Omeprazole as the outsider that prevents the employee (ATPase) from turning on the machine (proton pump). Omeprazole works by binding and inhibiting the proton pump, successfully reducing or stopping acid secretion for up to 36 hours [11].


How Effective are Famotidine and Omeprazole for Treating GERD?

According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Famotidine and Omeprazole are excellent medications that effectively treat GERD and other gastric conditions [12]. H2 blockers like Famotidine and PPIs like Omeprazole are some of the first-choice treatments for GERD patients. However, research suggests that Omeprazole might be more effective in treating GERD and related gastrointestinal conditions than famotidine [13].

One research study published in the Papich Handbook of Veterinary Drugs suggests that Omeprazole is more potent and long-lasting than H2 blockers like famotidine [14]. Another study states that while H2-receptor antagonists such as Famotidine are effective at first and may act faster than Omeprazole, the body quickly gets used to the medication, building up a tolerance and causing Famotidine to lose effectiveness [15].

Moreover, several clinical trials have assessed the efficacy of Famotidine and Omeprazole. One clinical trial compared the two medications in 60 patients with duodenal ulcers and concluded that Omeprazole showed greater healing rates than Famotidine in treating ulcers [16].

Another research found that Famotidine and Omeprazole effectively prevented ulcers in patients prescribed blood thinners, with PPIs such as Omeprazole performing better than Famotidine [17].

Dosage Information

How is Famotidine administered for GERD?

Famotidine is an oral medication that can be taken by mouth. However, Famotidine is also available as an injection for infusion into a vein. Moreover, Famotidine can be taken with or without food. Before taking oral Famotidine, shake the liquid suspension for around ten seconds and use the dosing syringe provided with the medicine.

Famotidine Dosage Infromation

Famotidine dosage for GERD is approved at 20 mg orally twice a day for six weeks [18]. However, the exact dosage would depend on the patient's health, condition, and age. The doctor can alter the prescription, especially if the patient faces kidney problems. Famotidine dosage for children depends on their body weight [19].

For heartburn conditions, famotidine dosage for patients 12 or older is between ten to twenty mg if taken to relieve symptoms. The famotidine dosage for patients 12 or older is the same for patients who wish to prevent heartburn. However, patients should not take over two doses of Famotidine within 24 hours.

How is Omeprazole Administered for GERD?

Omeprazole is present in the form of an oral suspension or capsule. Before taking the oral suspension, shake the bottle and use a dosing syringe. Alternatively, you can take a capsule. If you cannot consume the capsule hole, you can crush and mix it with applesauce or water and swallow the mix without chewing. However, the mixture should not be kept for later as crushed Omeprazole has a small shelf-life.

Omeprazole Dosage Information

The approved omeprazole dosage for GERD is 20 mg daily for four weeks [20]. However, your doctor can alter the dosage depending on your health or the presence of side effects. The dosage for children is based on their weight.

For patients wanting to relieve heartburn symptoms, adults should take 20 mg daily for two weeks every four months.

Side Effects

What are the Most Common Side Effects of Famotidine?

Some of the most common side effects of Famotidine include:

  • Headache
  • Dizziness
  • Constipation
  • Diarrhea
  • Nausea and vomiting
  • Muscle pain
  • Decreased libido
  • Dry mouth
  • Inability to have an erection
  • Fatigue

Are there any Potential Serious Side Effects of Famotidine?

If you experience any of the following serious side effects of Famotidine, seek medical help immediately:

  • Bleeding Gums
  • Blisters or peeling skin
  • Blood in urine
  • Difficulty breathing
  • Heart palpitations
  • Lack of appetite
  • Rashes on skin
  • Seizures
  • Swollen eyes
  • Delusions
  • Insomnia
  • Nose bleeds

What are the Most Common Side Effects of Omeprazole?

Some of the most common side effects of Omeprazole include:

  • Headaches
  • Stomach pain
  • Nausea and vomiting
  • Constipation
  • Diarrhea
  • Dizziness
  • Fatigue
  • Gas

Are There Any Potential Serious Side Effects of Omeprazole?

If you experience any of the following serious side effects of Omeprazole, seek medical help immediately:

  • Muscle pain
  • Bleeding gums
  • Blisters or skin rashes
  • Joint pain
  • Loss of appetite
  • Difficulty breathing
  • Pain while urinating
  • Mouth sores
  • Red eyes
  • Sore throat

Contraindications and Interactions

Contraindications and Important Interactions for Famotidine and Omeprazole



Hypersensitivity to Famotidine or any active ingredient

Cross-sensitivity in patients with hypersensitivity to cimetidine


Patients may experience hypersensitivity to substituted benzimidazoles or other active ingredients

Concomitant use of rilpivirine products

Drug/Medication Interactions


  • Atazanavir
  • Dasatinib
  • Azole antifungal such as itraconazole
  • Levo ketoconazole
  • pazopanib
  • Cimetidine and nizatidine


  • Warfarin
  • Citalopram
  • digoxin
  • HIV medication such as atazanavir and nelfinavir
  • Clopidogrel
  • Transplant medication such as tacrolimus
  • Diazepam
  • Cilostazol
  • Phenytoin

Food/Beverage/Supplement Interactions


  • St. John’s Wort
  • Alcohol
  • Nicotine


  • St. John’s Wort
  • Alcohol
  • Nicotine

Cost Comparison

How much do Famotidine and Omeprazole Cost?

Famotidine and Omeprazole are generic medicines that are available at low costs. The cost of a 20 mg famotidine dosage which contains six tablets, is $14.93, $2.49 per tablet [21]. An adult GERD patient will require a dosage worth four weeks, taking one a day, equating to $69.72. On the other hand, the cost of 20 mg omeprazole dosage, which contains 50 tablets, is $60.85, $1.22 per tablet [22]. An adult GERD patient will require a four-week dosage and take one tablet daily, equivalent to $34.

The popularity of Famotidine and Omeprazole

Famotidine and Omeprazole are one of the most prescribed medications for GERD patients. There are over 10 million prescriptions of Famotidine in the United States, with over three million estimated patients [23]. On the other hand, there are over 56 million prescriptions of Omeprazole in the United States, with over 13 million estimated patients [24].



Famotidine and Omeprazole are effective drugs for treating acid reflux, heartburn, and GERD. Famotidine is a histamine-2 blocker and indirectly reduces acid production, while Omeprazole directly blocks the enzyme responsible for acid production. Omeprazole may take longer to reach its full effect, and it has been associated with a higher risk of certain side effects.

Ultimately, choosing these two drugs depends on individual preferences and medical history. It is important to consult a healthcare provider before starting any medication to ensure it is safe and appropriate for your specific condition.