Does omeprazole have serious drug interactions?

Yael Cooperman, MD - Contributor Avatar

Reviewed by Yael Cooperman, MD, Ro, 

Written by Anna Brooks 

Yael Cooperman, MD - Contributor Avatar

Reviewed by Yael Cooperman, MD, Ro, 

Written by Anna Brooks 

last updated: Oct 13, 2020

5 min read

Occasional heartburn can be annoying, but when it happens frequently, medications like omeprazole (brand name Prilosec) or other proton pump inhibitors just might be your best friend. 

Omeprazole is a widely used drug to help manage conditions like peptic ulcers, erosive esophagitis, and gastroesophageal reflux disease (GERD). Omeprazole can be taken at the same time as many medications without any adverse reactions, but there are some drugs that you should avoid when taking omeprazole (Li, 2013).

While drug interactions among patients taking omeprazole aren’t common, it’s important to know which ones could react to avoid any unexpected—or potentially dangerous—side effects.


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What is a drug interaction?

If you’re taking more than one medication, there’s always a risk one could react with another. When this happens, it’s called a drug interaction, and each one is different. A drug interaction could have little to no effect on a person, while another could lead to serious health complications.  

The chances of experiencing drug interactions is also higher for those taking more than one medication at the same time, putting certain demographics more at risk. For example, a 2016 study found that older people were twice as likely to have a drug reaction compared to younger groups (Gujjarlamudi, 2016). And this makes sense. 

The older we get, the more likely it is that we’re taking multiple medications, and this phenomenon, known as polypharmacy, is common today (Masnoon, 2017). Between 2013 and 2016, nearly 25% of the population took three or more prescription drugs in a given month. While just 4% of people under the age of 18 took multiple prescription medications, almost 70% of adults over the age of 65 took three or more medications, and 40% of them took five or more drugs, according to the Centers for Disease Control and Prevention (CDC) (CDC, 2018). 

Which drugs interact with omeprazole?

While mild interactions have occurred for patients taking omeprazole in combination with a range of other drugs, serious interactions are less frequent. Blood thinners, antiretroviral medications used to treat HIV, and cancer treatments are just a few examples of drugs that may react with omeprazole, which we’ll get into more detail below (FDA, 2018).

  • Warfarin: Abnormal bleeding could result from mixing omeprazole and warfarin, a medication that prevents blood clots from forming.

  • Methotrexate: Because of the way our livers process medications, combining methotrexate, a medication used for arthritis and cancer therapy, with omeprazole can result in toxic levels of methotrexate in the body. 

  • Clopidogrel: Omeprazole could decrease the effectiveness of blood thinners like clopidogrel. Other drugs, which aren’t blood thinners but are similarly affected by omeprazole, include citalopram, cilostazol, phenytoin, diazepam, and digoxin.

  • Tacrolimus: Omeprazole may cause levels of tacrolimus — a medication used to prevent transplant rejection in patients who have received a kidney, heart, or liver transplant — to increase in the body.

  • Antiretrovirals: Certain antiretrovirals used to treat HIV can become less effective when taken alongside omeprazole. Examples include rilpivirine, atazanavir, nelfinavir, and saquinavir.

This doesn’t cover the full list of drugs that could interact with omeprazole. Make sure to speak with a health provider before taking this drug — especially if you’re taking other medications at the same time.

What is omeprazole? 

Omeprazole, also available under the brand name Prilosec, is a generic drug used to treat a number of gastro-related conditions. It falls into a class of medications called proton pump inhibitors (PPIs), which help suppress acid production in the stomach (Strand, 2017). Compared to other types of medications used to treat the same conditions, such as H2 blockers (brand name Zantac), PPIs have been found to be more effective in treating the same digestive problems (Strand, 2017). 

Here’s a little more on the main uses of omeprazole (FDA, 2018): 

  • Gastroesophageal reflux disease (GERD): Omeprazole helps treat and manage chronic heartburn and other symptoms of GERD.

  • Erosive esophagitis: Omeprazole manages symptoms and helps heal erosive esophagitis quickly.

  • Duodenal and gastric ulcers: PPIs like omeprazole help prevent gastric and duodenal ulcers, as well as heal existing ones.

  • Zollinger-Ellison syndrome: Omeprazole is used to treat Zollinger-Ellison syndrome, a rare condition marked by tumors in the small intestine and pancreas.

Available by prescription and over-the-counter (OTC), omeprazole is also used to treat Helicobacter pylori infections, heal damage caused by frequent acid reflux, and prevent bleeding in the upper gastrointestinal tract (Khan, 2018). Omeprazole is taken once per day for a cycle of anywhere from 10 days to 8 weeks, depending on what your healthcare provider recommends (FDA, 2018). 

It comes as a delayed-release tablet or oral suspension for those who can’t or have trouble swallowing pills. Make sure to take omeprazole 30-60 minutes before eating. Dosages come in 10 mg, 20 mg, 40 mg, and 60 mg and will vary depending on factors like age, weight, and what health condition it’s being used for. Omeprazole usually starts working within an hour or less, but it may take up to four days for your body to feel the full effects (FDA, 2018). 

Side effects of omeprazole

The risk of having a serious reaction to omeprazole is low. However, there can be adverse effects if you don’t take the drug as recommended. The most common side effects are typically mild and may include: dizziness, headache, abdominal pain, nausea, vomiting, constipation, and diarrhea (Casciaro, 2019). 

Serious or life-threatening health outcomes from omeprazole are rare, but they can happen. Taking omeprazole at the same time as blood thinners could reduce the blood thinners’ effectiveness (FDA, 2018). Studies have found that long-term use of the drug can put patients at a higher risk of developing kidney disease, bone fractures, and irritable bowel disease (Kinoshita, 2018). While adverse events aren’t common, they are often triggered by allergies or interactions with other drugs.

Who should not take omeprazole

Omeprazole is considered a safe and well-tolerated drug for many patients. However, there are people who should avoid the drug. Do not take omeprazole if you are allergic to it or have ever had a reaction to other proton pump inhibitors. (Casciaro, 2019).  

If you’re pregnant or breastfeeding, speak to a healthcare provider before taking omeprazole. Studies have found traces of omeprazole in the breastmilk of nursing women. However, no significant adverse effects have been noted as of yet (FDA, 2018). There also is little to no conclusive evidence yet on if omeprazole presents any risks to pregnant women. The safety and effectiveness of omeprazole has not been established in pediatric patients less than one year old.

When to talk with a healthcare provider about heartburn

If you experience heartburn more than once or twice a week, it might be time to reach out to a healthcare professional. Not only is frequent heartburn uncomfortable, but it could also be an indication of an underlying condition like GERD, a digestive disease that causes inflammation of the esophagus due to excess acid reflux. GERD affects roughly 23% of adults in North America (El-Serag, 2014). 

Left untreated, GERD can lead to serious or even permanent damage to the esophagus. It can also cause a potentially cancerous condition called Barrett’s esophagus, which causes changes in the cells that line your esophagus and can lead to serious health complications (Wang, 2015).

Frequent heartburn isn’t the only symptom of digestive disease. Talk to a healthcare professional if you are experiencing any of the following symptoms (Clarrett, 2018):

  • Difficulty or pain swallowing

  • Frequent burping

  • Gum inflammation

  • Laryngitis 

  • Bad breath or a sour taste in your mouth, especially after lying down

  • Chest pain

  • Dizziness

  • Stomach pain or cramps

  • Black or tarry stool

  • Any obvious signs of gastric bleeding 

Talk to a healthcare provider before taking PPIs, especially if you are taking multiple medications or have other health conditions. 


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

October 13, 2020

Written by

Anna Brooks

Fact checked by

Yael Cooperman, MD

About the medical reviewer

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.