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Can Omeprazole Cause Green Stool? All Side Effects Of Omeprazole

Omeprazole is used to treat different gut diseases, including peptic ulcers, gastroesophageal reflux disease or GERD, and Zollinger-Ellison syndrome. Like many other drugs, Omeprazole can also cause side effects. But, can Omeprazole cause green stool? Any change in the stool color and texture can be expected if you take medications that affect the gastrointestinal system.

So, one may ask, why Omeprazole green stool occurs?

Yes, Omeprazole can be a reason for color change in stool. Diarrhea is included in the list of common side effects of Omeprazole. It is well known that diarrhea involves more bowel movements than average. Anything that causes the bowel movements to pass quickly through the intestine can be a reason for the color change. 

Learn more by continuing to read.

Table of Content

Can Omeprazole Cause Green Stools?

As mentioned earlier, diarrhea is the most common side effect of Omeprazole, and it is the main reason for stool to appear green.

The standard color of stool is usually brown. This is due to the breakdown of bile pigments in the intestine by some chemical components and bacteria. The bile pigments are present in bilirubin, the final product formed by the breakdown of hemoglobin in red blood cells in the liver. This bilirubin undergoes breakdown in the intestine before its excretion. The large intestine’s digestive enzymes and bacteria are responsible for this process.


But, what if stool passes too quickly through the intestine? This can occur in diarrhea, which causes the stool to pass rapidly through the intestine. You have noticed that a person facing diarrhea has more than one bowel movement per day. This means he is passing stool with a shorter gap between them, or you can say he is passing stool quickly.

When the stool is passing quickly through the intestine, bile pigments in the intestine cannot undergo complete breakdown by enzymes and bacteria in the large intestine. This incomplete breakdown of bile pigment causes a change in the color of stools. The stool may appear green or yellow. So, you can say Omeprazole causes green stools by causing diarrhea.

Why Do People Use Omeprazole?

As discussed earlier, Omeprazole is a medication used to treat several gastrointestinal disorders.

Omeprazole drug information infographic

Gastroesophageal Reflux Disease

It can cure gastroesophageal reflux disease, a condition in which acidic fluid from the stomach flows back into the esophagus due to malfunctioning of the circular band at the bottom of the esophagus. 

This circular band works by preventing the backflow movement of food from the stomach into the esophagus. Omeprazole treats this condition simply by reducing the acid production in the stomach, thus preventing the acidic backflow movement. 

Peptic Ulcer

Omeprazole is also used to cure peptic ulcers, a condition in which holes or open sores are produced on the stomach’s inner lining, including the lower portion of the esophagus and upper portion of the small intestine. 

A peptic ulcer can be caused by removing the inner mucus membrane of the stomach. 

This inner lining of mucus in the stomach is responsible for protecting stomach walls against gastric acid. This lining can be damaged due to the high production of gastric acid, creating holes in the stomach lining. 


Omeprazole treats peptic ulcers by reducing the gastric acid production in the stomach and healing the wholes already formed inside the linings.

Zollinger-Ellinger Syndrome

Omeprazole can also treat Zollinger-Ellinger syndrome. This situation is caused by over-secretion of the gastrin hormone, which further causes the overproduction of gastric acid. This gastric acid can cause peptic ulcers and some other gastric complications. Omeprazole inhibits this overproduction of gastric acid, thus treating this condition.

Erosive And Eosinophilic Esophagitis

This medication can also be used to treat erosive and eosinophilic esophagitis. Erosive esophagitis occurs when the esophagus becomes inflamed due to some medications, GERD, or bad eating habits like excessive consumption. 

Similarly, eosinophilic esophagitis is also an inflammation of the esophagus caused by the presence of eosinophils.

In a healthy esophagus, no white blood cells are in the esophagus. But, in eosinophilic esophagitis, these eosinophils start damaging the tissues whenever food is taken, causing pain. Omeprazole can be used to treat erosive esophagitis as well as eosinophilic esophagitis.

Duodenal Ulcers

This can also be recommended to cure duodenal ulcers. Duodenal ulcer is damage to the inner lining of the upper portion of the small intestine. 

It can be caused by the overproduction of gastric juice from the stomach into the intestine. Omeprazole works by decreasing this acid production.

How Does Omeprazole Work?

Omeprazole is a proton pump inhibitor because it inhibits or blocks the gastric proton pump. Omeprazole reduces stomach acid production by blocking an enzyme called H+/K+ ATPase, also known as a gastric proton pump, responsible for acid production. The proton pump is located in the parietal cells of the stomach wall. Omeprazole affects both baselines and stimulates gastric acid secretion. 

How Long Can You Safely Take Omeprazole?

You should not use it for more than 14 days. It may cause side effects if you keep taking it without a prescription. You may experience specific side effects if you take Omeprazole longer than a year, such as bone fractures and gastritis. Several signs indicate vitamin B12 deficiency, such as weakness, fatigue, sore tongues, mouth ulcers, and pins and needles.


Can Omeprazole Interact with Other Drugs?

There is the potential for Omeprazole to interfere with the functions of other drugs. It may reduce the absorption and effectiveness of other drugs. The side effects can be mild or severe.

Some drugs that can interfere with Omeprazole include:

  • Warfarin
  • Clopidogrel
  • Diazepam
  • Digoxin

Some diseases can become worse while using Omeprazole. These diseases include cancer, dementia, hepatic diseases, and bone diseases, including osteoporosis.

Common Side Effects of Omeprazole: Omeprazole Green Stool

Besides diarrhea, Omeprazole can also cause many other side effects.

  • A severe stomachache, bloody or watery diarrhea
  • Experiencing new thigh, back, or wrist pain
  • Nervousness
  • Kidney problems may further cause a fever, rash, fatigue, nausea, loss of appetite, less urination than usual, weight gain, blood in your urine. Also, It can cause pain in the joints. In recent years, chronic kidney disease (CKD) has been linked to proton pump inhibitors (PPI), particularly Omeprazole. It can even cause kidney failure if you use it for too long.
  • Sweating
  • Convulsions (seizure)
  • Diarrhea
  • Weakness
  • Abnormal heartbeat
  • Skin rash
  • Blurred vision
  • Headache
  • Dizziness
  • Upper respiratory tract infection
  • Constipation
  • Flatulence
  • Omeprazole consumption can lead to muscle weakness, which eventually results in arthritis. Among the side effects of Omeprazole are frequent joint pains.
  • As a side effect, some women taking Omeprazole during pregnancy have reported additional bloating, swelling, or weight gain. While taking the medication, the fetus may also experience weight gain.

Is There A Substitute For Omeprazole To Avoid Green Stool  ?

Some other proton pump inhibitors such as esomeprazole (Nexium), pantoprazole (Protonix), and lansoprazole (Prevacid) can be used as an alternative to omeprazole. It is best to consult your healthcare provider or pharmacist to determine which medication is proper for you.


Question: Can I take Omeprazole for an upset stomach?

Answer: It can be used to cure stomach problems. Many stomach complications are just due to the high level of gastric juice in it. Overproduction of gastric juice can even cause an ulcer in the stomach. So, Omeprazole can be used in this condition, as it works by blocking the production of acidic gastric juice. 

Question: Does omeprazole increase appetite?

Answer: According to scientific evidence, Omeprazole and other proton pump inhibitors do not increase appetite. According to researchers, 97.5% of people taking proton pump inhibitors did not experience changes in their appetite. 

Question: Is drinking water beneficial for acid reflux?

Answer: Acidity and GERD symptoms can be reduced by drinking water. If you drink water after eating, you can dilute the acid in the stomach, which can cause less heartburn.


Omeprazole causes green stool by causing diarrhea. The frequent bowel movements during diarrhea reduce the time gap between stools, preventing the bile pigments from breaking down entirely in the intestine. 

Furthermore, it may cause a wide variety of side effects and interact with other drugs, causing severe complications.

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