Omeprazole Side Effects

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So your doctor has recommended that you take omeprazole, a medicine used to help stomach issues. While omeprazole can certainly be effective, there are some things you should know including the potential side effects.

Before you take omeprazole, let’s take a look at what it is, who it’s for, the risks, as well as the side effects. Understanding everything there is to know about a drug is essential to ensure it’s suitable for you.

What Is Omeprazole?

Medical News Today explains, “Omeprazole belongs to the proton pump inhibitor (PPI) class of medications.” It’s a generic drug that your doctor can prescribe. However, it is also available over-the-counter (OTC).

Even though many people can tolerate this medication, there are some risks when using it for long periods of time. Next, let’s find out what this drug is used for.

What Does Omeprazole Treat?

Omeprazole is used to treat conditions that cause too much acid in the stomach. In some cases, omeprazole is used in combination therapy, meaning you take it with other medications.

So what does it treat? Medical News Today says the Food and Drug Administration (FDA) has approved omeprazole capsules and granules for medical conditions like intestinal ulcers and stomach ulcers in adults. It is also used to treat gastroesophageal reflux disease (GERD), helicobacter pylori infections, and Zollinger-Ellison syndrome.

How Does It Work?

When you take omeprazole, it works by decreasing the amount of acid your stomach produces. “It does this by blocking a system in the cells of your stomach called the proton pump,” notes Medical News Today.

When the proton pump is blocked, less stomach acid is produced. This can decrease your symptoms. It’s worth noting, doctors don’t recommend omeprazole tablets for immediate heartburn relief. It can take the drug up to 4-days before it has a full effect.

Who Can Take Omeprazole?

Before we dive into the side effects of this drug, let’s establish who it’s suitable for. The National Health Service (NHS) explains omeprazole is suitable for adults, including pregnant and breastfeeding women.

It can also be suitable for children and infants if it’s prescribed by a doctor. However, make sure you consult your doctor before taking a new medication to ensure it’s safe for you. It may not be suitable if you’ve had an allergic reaction to other medicines, if you have liver problems, or if you’re having an endoscopy.

Omeprazole Side Effects

Just like most medications, there are potential side effects that you should be aware of. Some of the more common omeprazole side effects for adults include headache, dizziness, stomach pain, gas, nausea, vomiting, and diarrhea.

Children’s side effects are slightly different. They may experience the same side effects as adults but they can also experience fever too.

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How Long Do Side Effects Last?

Even though these side effects are mild, they still aren’t pleasant. The good news is, if you experience mild omeprazole side effects, they typically go away within a few days or a couple of weeks.

However, if the side effects become more severe (which we’ll discuss next), or they don’t go away, make sure you talk to your doctor.

Serious Side Effects

Serious side effects are rare, but nonetheless, it’s important to be aware of the risks. If you do experience any of these serious side effects you should contact your doctor right away.

If your symptoms feel life-threatening then make sure you get emergency medical help immediately. Let’s take a look at some of the serious side effects of omeprazole.

Low Magnesium Levels

Using omeprazole for long periods of time (3-months or longer) may cause low magnesium levels. This can be serious because symptoms include seizures, tremors, and abnormal heart rate.

Other symptoms include jitteriness, muscle weakness, cramps, muscle aches, and spasm of your hands, feet, or voice box.

Vitamin B-12 Deficiency

Another serious side effect of omeprazole is a vitamin B-12 deficiency. This can also occur after taking the drug for long periods of time (longer than 3-years) because it can make it harder for your body to absorb this essential nutrient.

Signs and symptoms of a vitamin B-12 deficiency include numbness or tingling in your hands or feet, poor muscle coordination, and nervousness. You may also experience neuritis (inflammation of a nerve), or changes in menstruation.

Severe Diarrhea

Omeprazole may also cause severe diarrhea. This can be triggered by a Clostridium difficile (also known as C. diff) infection.

Symptoms may include watery stool, stomach pain, and a persistent fever. If you suspect you’re suffering from a C. diff infection, contact your doctor right away.


Inflammation of your stomach lining is another serious side effect of omeprazole. Signs that you may be suffering from inflammation include stomach pain, nausea, and vomiting. You may also experience weight loss.

Once again, if you’re taking omeprazole and experience any of these rare but serious side effects, make sure you contact your doctor to help determine the best course of action for you.

Drug Interactions

Omeprazole can also have interactions with other drugs. It’s important to discuss this with your doctor to ensure the drugs you are currently taking won’t conflict with omeprazole.

It’s not recommended to take omeprazole with atazanavir, rilpivirine, nelfinavir, and clopidogrel. Combining these drugs can cause dangerous interactions in the body.


The proper dosage of omeprazole will depend on a variety of factors. These include your age, the condition it’s treating, the severity of your condition, as well as other medical conditions you currently have.

If you purchase this drug OTC be sure to read the directions on the bottle. However, if it’s prescribed by your doctor, follow their instructions. Finally, if you’re unsure of what dosage you should take, talk with your doctor.

The information on this site is not intended or implied to be a substitute for professional medical advice, diagnosis, or treatment. All content, including text, graphics, images, and information, contained on or available through this website is for general information purposes only.

Clarissa Vanner

Clarissa Vanner

Clarissa is the Junior Managing Editor of ActiveBeat. She aspires to live a healthy lifestyle by staying active and eating foods that nourish her body, but she isn't afraid to indulge in a little chocolate here and there! Clarissa loves cooking, being outdoors, and spending time with her dog. In her free time, you'll find her relaxing in her hammock or curled up on the couch reading a book.