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Prilosec is the first of a new class of drugs that combat acid secretion by blocking the final step.

This so-called proton pump is prescribed for the short-term treatment of duodenal ulcer and for conditions of abnormal acidity such as serious heartburn (GERD) or the rare Zollinger-Ellison syndrome.

It has a very quick onset and is extremely effective in reducing stomach acid.

Prilosec should not be prescribed as maintenance therapy to keep ulcers from coming back.

Side Effects and Interactions

Prilosec is generally well tolerated. However, headache, diarrhea, stomachache, muscle weakness and rash have been reported.

Other adverse reactions that have been reported less commonly include constipation, cough, fatigue, sore throat and vomiting. Report any symptoms or suspected reactions to your physician promptly.

Prilosec slows the elimination of several drugs that must be processed by the liver, including the anxiety medicine Valium, the anti-epileptic Dilantin and the blood thinner Coumadin.

Blood levels of these drugs may rise and side effects become a problem. If you take both Prilosec and Coumadin, tell your doctor right away if you experience any unusual bruising, bleeding, reddish urine or blackened stools. Prilosec is also reported to blood levels of Sandimmune or Antabuse.

Many other prescription drugs require acidity for absorption. Prilosec can interfere with such medicines, which include Nizoral, ampicillin and iron supplements, among others.

People taking acid-suppressing drugs such as Prilosec should not take enteric-coated peppermint oil. The enteric coating is designed to keep the oil from being absorbed until it reaches the more alkaline lower intestine. But when there is very little stomach acid, the enteric coating may dissolve prematurely, releasing the oil into the stomach.

In older people with too little stomach acid or in patients taking a strong acid suppressor such as Prilosec, vitamin B12 absorption may be impaired. Cranberry juice appears to improve the absorption of this crucial vitamin in such cases.

Be sure to check with your pharmacist and physician about potential interactions before taking any other medication or herb in combination with Prilosec.

Special Precautions

Animal studies have shown that Prilosec is associated with a dose-related increase in stomach cancers. It is not known whether this risk also applies to humans.

In addition, because it is so effective at reducing stomach acid concentrations, patients taking this medicine have higher levels of certain microorganisms in their stomachs than would normally survive there.

Scientists do not yet know whether these bacteria have negative long-term consequences.

Regular supplementation with vitamins C and E might in theory provide protection against nitrosamines produced by the bacteria.

People with liver disease have more trouble metabolizing Prilosec. Older people also remove the drug from circulation more slowly.

Taking the Medicine

Prilosec should be taken before meals.

These delayed-release capsules should not be opened, crushed or chewed, as that might expose them to stomach acid. The medication can be inactivated by acid.

Antacids may be taken with Prilosec if they are needed.

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.” .
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I have taken 40 mg twice daily since 2000. My stomach has felt great since I started this. It has all but eliminated Barrett syndrome!!!! I have ZERO issues!

OME can cause blurred vision, my right eye can not focus, I want to know how to fix it…

All I can say is WEIGHT GAIN helped me, RADICAL WEIGHT GAIN IN ARMS AND LEGS, AND BELLY BLOAT TO END ALL BELLY BLOAT!! :( Yes, it solves the GERD, but I can’t fit into any of my clothes.

Omeprazol can cause b12 deficiency and b12 deficiency can cause nerve damage. Blurry vision could be nerve damage. Check your b12 level.

My husband was taking ranitidine for years without any side effects. For some unknown reasons a doctor he visited for his throat changed it to Smallwood. Gradually a man who had been my ‘telephone directory’ could no longer remember numbers, the date and other short term memory issues. His cognition is fine. I read about memory issues with oemeprazole and so we went back to ranitidine. I see a little improvement after one week. Older people should not be put on this drug. Bernice

I have extreme nausea and very weak feeling after only two days of taking omeprozole.

I need to quit taking Omeprazole. I do not have heartburn, so are there any rebound effects I may suffer? I have taken them for about two years.

Many people who stop taking their heartburn medications do experience painful rebound reflux or hyperacidity.
We have written about this topic at length before. Take a look at the following articles for advice when weaning off of these medications.


Thank you all for your comments. This is the only site I have found that has contained much about the side effects I’ve recently experienced. I’ve only taken Prilosec OTC 20 mg pills since late April, and those only occasionally. I got immediate relief, and found them to be continuously effective even taking only two pills or fewer per week. However, after I’d taken only about 20 pills, I noticed random itchiness on my shoulder blades at first, then also on my face throughout that first night. I stopped taking them immediately, but the itching immediately progressed to sun sensitivity on the back of my neck, my forearms, and my face, causing slight puffiness and mild acne too.
It’s been two weeks today since my last pill, and the sun sensitivity continues. The itching subsided, but is not gone yet either. Also, I’ve had some insomnia, which I had not had before two weeks ago. The one question I still have after reading this and several other websites is: how long does it take for the sun sensitivity to go away? I am a 53 year-old male with, thankfully, no other health problems than the throat irritation and hoarseness due to a hiatus hernia that eventually led me to try Prilosec.

I could not tolerate Omeprazol any more and have been switched to Ranitidine, which is less invasive. I have made drastic changes to my eating habits, and have had notable improvement with me acid reflux.
I do have Barrett’s which developed while I was on Omeprazol.

I’ve recently been diagnosed with pernicious anemia and have received the first six injections of vitamin B12. Awaiting results of blood test for levels of B12. I read that prilosec impairs the absorption of B12, hence injections instead of pills which I would very much prefer. Can one wean oneself off prilosec and find an alternative solution. I have been taking prilosec for about 7 years.

I have been on prilosec for 11 years now. I was diagnosed with acid reflux when my ENT doc looked in my sinus and saw I had a deviated septum and reflux damadge in my esophogus. He started me on nexium to heal my throat and after that ran out I started on prilosec to keep the acid at bay.
I used to be constantly tired and had a hard time remembering things so after looking things up on prilosec I noticed the vitamin b deficiency problem. When you don’t get enough vitamin b then you can have memory problems and fatigue. I now take Vit B Complex daily and I also take Calcium Citrate to prevent osteoporosis (it has the acid in it to process in your body since I don’t have it anymore when taking prilosec – other calcium supplements don’t absorb without acid).
I have more energy now but could be better still. I also am able to remember better but still have times when it is hard to remember specific instances of things but that may be normal with age. I want to try to get off Prilosec.
Every time I try to get off it the rebound acid is horrendous. I am going to give it another try by trying to taper off my prilosec little by little by using Tums and Gaviscon in addition to 1/2 dose of my prilosec. wish me luck. I read on another site that it takes the body 2 months for the stomach cells to revert back to normal after taking a PPI.

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