Lansoprazole Side Effects

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Millions of people across the world use lansoprazole, a popular proton-pump inhibitor (PPI) medication that protects your stomach health and saves you from various digestive ailments. While some use it occasionally to fight dyspepsia and similar everyday complaints, others may make it a part of their daily life to fight more serious health issues. Available under the brand name Prevacid, this medication is generally presumed safe for health and everyday use; however, studies have shown that many people may develop lansoprazole side effects at some point in life, especially if they do not take it as directed. Knowing these side effects and how to prevent them is imperative to maintain good health and avoid unnecessary complications.

An Outline of Lansoprazole and its Uses

Lansoprazole is a prescription medication in two forms: delayed-release orally disintegrating tablets and delayed-release oral capsules. As a delayed-release medication, it does not release its chemical content until it passes through the stomach to enter the bloodstream. This mechanism of action prevents lansoprazole from undergoing inactivation in the stomach. Lansoprazole is most commonly available under the brand name Prevacid and multiple other generic versions. Generic versions are generally cheaper than the brand name and may come in various strengths.

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The biggest use of lansoprazole is its ability to reduce the stomach acid content in the body. The following are the most common indications for using this medication:

  • Treating ulcers in the stomach and duodenum
  • Preventing and treating stomach ulcers secondary to the use of non-steroidal anti-inflammatory drugs (NSAIDs)
  • Treating heartburn due to the underlying gastroesophageal reflux disease (GERD)
  • Managing a stomach infection due to a bacterium called Helicobacter pylori in combination with an appropriate antibiotic
  • Treating hypersecretory conditions (conditions where the stomach secretes too much acid), for example, Zollinger Ellison Syndrome)
  • Managing erosive esophagitis, a condition that causes ulcers and inflammation in the esophagus

Common Lansoprazole Side Effects

Following are the lansoprazole side effects long term-term and short-term.

Most Common Side Effects

The most common Prevacid side effects include the following:

  • Diarrhea
  • Headache
  • Nausea
  • Stomach pain
  • Constipation

The mild side effects mentioned above usually go away within a few days or weeks on their own. However, talk to a doctor if they become severe or do not go away.

Serious Side Effects of Lansoprazole

Outlined below are some serious Prevacid side effects for adults. Experts recommend calling a doctor right away if a person develops these symptoms or feels as if they are having a medical emergency:

Vitamin B12 Deficiency

Taking lansoprazole every day for a long time, usually for years, may make it harder for the body to absorb vitamin B12. As a result, its blood levels may drop, leading to the following symptoms:

  • Nervousness
  • Changes in menstruation
  • Poor muscle coordination
  • Tingling and numbness in hands and feet
  • Neuritis, or nerve inflammation

Poor Magnesium Levels

Continued lansoprazole for at least three months or more may cause magnesium levels to drop, leading to symptoms like:

  • Seizures
  • Abnormal or fast heart rate
  • Dizziness
  • Jitters
  • Muscle weakness
  • Tremors (jerking movements or shaking)
  • Spasms in your hands and feet
  • Spasms of your voice box
  • Cramps or muscle aches

Allergic Reactions

Following are the symptoms of a serious allergic reaction to lansoprazole and warrant immediate medical help:

  • Rash
  • Trouble breathing
  • Tightness in throat
  • Swelling of the face

Bacterial Infection

Continued use of lansoprazole may put users at risk of acquiring an infection from C. difficile, a bacterial strain that may cause the following symptoms:

  • Fever
  • Watery diarrhea
  • Stomach pain

Lansoprazole Interactions and Risks

Lansoprazole capsules can interact with other vitamins, herbs, or medications a person may take simultaneously. This interaction may lead to various outcomes, such as reduced efficiency of lansoprazole or other medications taken together. To minimize these interactions, a doctor must manage all medications a person is taking with great care. For this reason, patients must be honest about everything they are already taking before adding lansoprazole to their daily routine.

Following are different types of interactions that may occur when you combine lansoprazole with other drugs:

Interactions that increase side effects

Combining lansoprazole with the following drugs may increase the risk of acquiring side effects from these drugs:


You may experience more bleeding if you combine warfarin with lansoprazole. Hence, a doctor will have to keep a close eye on your lab results and monitor the warfarin dose accordingly.


Lansoprazole may increase the digoxin levels in the blood, putting a user at risk of side effects.


Lansoprazole also increases the blood levels of methotrexate, reinforcing the side effects. A doctor may test the methotrexate levels in the body periodically and stop lansoprazole if the levels are too high.


A person taking lansoprazole with Tacrolimus may experience more side effects due to the latter because of its elevated levels. A doctor may need to adjust the doses of both medications in people who need to take them together.

Interactions that make lansoprazole less effective

Using lansoprazole with certain medications may reduce its efficacy, making it ineffective in treating the underlying condition. Some examples of these medications include the following:


Lansoprazole may not work well enough for a person taking it with sucralfate. Hence, they must space both drugs by at least 30 minutes to avoid interactions.


Lansoprazole may not work efficiently with rifampicin.

St. John’s wort

St. John’s wort can also reduce the efficacy of lansoprazole when taken together.

Interactions that make other drugs less effective

Combining lansoprazole with certain drugs may interfere with the latter’s efficacy, primarily due to their reduced dosages in the blood. Some examples may include the following:


Lansoprazole interferes with the way the body absorbs ampicillin, reducing its efficacy and potency in treating the underlying infection.

Mycophenolate mofetil

Lansoprazole stops the body from absorbing this medication properly, rendering it less effective. Experts are not sure how this interaction may affect the body; hence, a doctor must carefully analyze if an individual should use both medications together

Ketoconazole & itraconazole

The efficacy of these antifungal drugs may take a dip when taken with lansoprazole, reducing their ability to fight fungal infection.


Lansoprazole can mess with the working of theophylline, a medication used to manage chronic obstructive pulmonary disease (COPD) or asthma.

Iron salts

Lansoprazole can also interfere with the absorption of iron salts in the body.

Lansoprazole Warnings to Remember

If you or someone you love has recently started taking lansoprazole or is considering taking it, keep the following warnings in mind:

Bone Fractures Warnings

Individuals who take multiple doses of lansoprazole for at least one year or longer may be at a higher risk of acquiring bone fractures. These fractures may occur in the spine, wrist, or hips. Hence, it is imperative to discuss these risks with a doctor and take the medication exactly as prescribed with the lowest possible dose for the shortest possible time.

Diarrhea Warning

In some people, taking lansoprazole may increase their risk of acquiring severe diarrhea. This diarrhea is usually secondary to an infection in the intestines caused by Clostridium difficile bacterium. Contact a doctor immediately if you experience severe watery diarrhea, fever, and stomach pain that does not go away.

Kidney Damage Warning

Lansoprazole can cause damage to the kidneys at any point during treatment. Keep a close eye on any renal symptoms and call a doctor if you feel pain in your sides and back, experience changes in urination, or see blood in urine during treatment.

SLE and CLE Warning

Treatment with lansoprazole can put a person at risk of acquiring systemic lupus erythematosus (SLE) or cutaneous lupus erythematosus (CLE). Both SLE and CLE are autoimmune diseases with variable symptoms. The symptoms of SLE may include weight loss, tiredness, fever, stomach pain, heartburn, blood clots, and joint pain. CLE, on the other hand, may cause rashes on the nose and skin.

Fundic Gland Polyps Warnings

Long-term use of lansoprazole, especially for a year or more, may put a person at risk of fundic gland polyps. These polyps are growths along the stomach lining that may become cancerous.

Warning for Pregnant Women

Research so far has not confirmed any risks to the fetus due to lansoprazole use by mothers. However, more studies are needed to further confirm these results. Talk to the doctor if you are pregnant or planning to conceive while on this drug to discuss the possible risks and adjustments if needed.

Warning for Breastfeeding Mothers

Experts are not sure if lansoprazole can pass into breast milk to cause side effects in the baby. Talk to a doctor about the possibility of this transfer and ask if taking lansoprazole is safe during nursing.

Minimizing Lansoprazole Side Effects: Important Considerations

Keep the following considerations in mind if a doctor prescribes lansoprazole to you to ensure that you do not experience any side effects:

  • Take the medication half an hour before having a meal
  • Take the drug exactly as prescribed during the times recommended by the doctor
  • Do not cut, crush, or chew the medication. You may consider opening the capsule and mixing its content with food or beverage; however, seek professional advice before going ahead with it
  • Do not store lansoprazole in damp or moist areas, such as bathrooms
  • Keep lansoprazole at room temperature, possibly between 68°F and 77°F  or 20°C and 25°C).

If you stop taking lansoprazole all of a sudden or choose to discontinue it completely, your underlying condition may worsen, and the symptoms may not improve. If you miss a dose or do not take the medication on schedule, it may not work well or stop working completely. On the other hand, taking too much lansoprazole may cause it to reach a dangerously high level in the body, leading to symptoms like:

  • Nausea
  • Stomach pain
  • Diarrhea
  • Headache
  • Constipation


How does lansoprazole work?

Lansoprazole belongs to a group of drugs known as proton pump inhibitors or PPIs. These medications interfere with stomach acid secretion by blocking the proton pumps on the stomach cell lining. By reducing the stomach acid content, lansoprazole helps relieve the symptoms of indigestion and prevents excessive acid from returning to the esophagus to relieve heartburn.

How long does lansoprazole take to work?

The duration it takes for lansoprazole to work depends on the condition it treats. If you take it for indigestion or heartburn, you may feel relief immediately or in a few days. For more serious conditions, such as a peptic ulcer, treatment may continue for weeks to acquire full benefits.

Who should not take lansoprazole?

The following people must inform their doctor about their circumstances before they start using lansoprazole as it may not be safe for them:

  • People with liver issues
  • People who are allergic to PPIs
  • People who have experienced an allergic reaction to lansoprazole or any other medication in the past

Which drugs should I not combine with lansoprazole?

Combining the following drugs with lansoprazole is not recommended as the combination may lead to dangerous side effects:

  • HIV drugs, such as saquinavir, may increase its levels in the body, leading to more effects than needed
  • HIV drugs, such as nelfinavir, atazanavir, and rilpivirine, may decrease their levels and reduce their efficacy

How long does lansoprazole stay in your system?

While the exact duration may vary from one person to another, lansoprazole mostly gets out of the body within 24 hours after the last dose.

Will I experience any lansoprazole side effects after stopping it?

When a person stops lansoprazole, they may experience rebound acid secretion, a condition where the amount of acid secretion in their stomach significantly increases. The condition usually reverts within 2 weeks.

Does lansoprazole cause weight gain?

Lansoprazole does not directly cause weight gain.

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