What Not to Mix with Lansoprazole?

October 15, 2025 •

3 min read

Proton pump inhibitors (PPIs), like lansoprazole, are among the most widely used classes of drugs in the world [1.7.1]. To ensure this common medication works safely and effectively, it's crucial to understand what not to mix with lansoprazole.

Quick Summary

Lansoprazole can interact with various medications, supplements, and foods, potentially altering its effectiveness or increasing side effect risks. Always consult a healthcare provider about your current medications before starting treatment.

Key Points

Drug Interactions: Lansoprazole can interact with blood thinners (warfarin), heart medication (digoxin), methotrexate, and certain HIV drugs [1.2.1].
Supplement Caution: Do not take St. John's Wort with lansoprazole as it reduces its effectiveness [1.9.5]. Long-term use may also decrease absorption of Vitamin B12 and iron [1.8.4].
Timing is Key: Take lansoprazole on an empty stomach, at least 30 minutes before a meal, as food can reduce its absorption by over 50% [1.3.3].
Acid-Dependent Drugs: Medications requiring stomach acid for absorption, like some antifungals (ketoconazole) and iron supplements, may become less effective [1.8.4].
Consult a Professional: Always inform your doctor or pharmacist about all medications, supplements, and herbal products you are taking before starting lansoprazole [1.9.1].
Alcohol: While not a direct interaction, alcohol can worsen the underlying condition (e.g., acid reflux) and may increase side effects like dizziness [1.4.5, 1.4.2].
Sucralfate: If you also take sucralfate, take it at least 30 minutes after lansoprazole to avoid absorption issues [1.9.4].

Understanding Lansoprazole and Its Function

Lansoprazole is a widely prescribed medication belonging to a class of drugs known as proton pump inhibitors (PPIs) [1.5.3]. Its primary function is to reduce the amount of acid produced in the stomach [1.5.2]. This makes it effective for treating conditions such as gastroesophageal reflux disease (GORD), indigestion, heartburn, and stomach ulcers [1.5.5]. It works by blocking the 'proton pumps'—enzymes in the stomach lining responsible for making acid [1.9.5]. While generally safe, its effectiveness and safety can be compromised by interactions with other substances.

Major Prescription Drug Interactions

Lansoprazole can interfere with how your body absorbs or metabolizes other medications. This can either reduce the effectiveness of the other drug or increase the risk of side effects [1.2.1]. It is essential to inform your doctor of all medications you are taking [1.9.1].

Medications Dependent on Stomach Acid

By design, lansoprazole reduces stomach acidity. This change in pH can decrease the absorption of drugs that require an acidic environment to be effective [1.6.3].

Antifungal Agents: The absorption of antifungals like ketoconazole and itraconazole can be significantly reduced, making them less effective at treating infections [1.2.1, 1.8.4].
HIV Medications: Certain HIV drugs, such as atazanavir and nelfinavir, may have their efficacy decreased when taken with lansoprazole [1.2.1, 1.2.4].
Iron Salts: Your body may not absorb iron supplements as well, which can be a concern for individuals with anemia or iron deficiency [1.8.1, 1.8.2].

Medications Metabolized by the Liver

Lansoprazole is broken down in the liver by specific enzymes (CYP2C19 and CYP3A4) [1.6.3]. It can compete with or influence other drugs that use the same pathways.

Warfarin: This blood thinner's effects can be altered, potentially increasing the risk of bleeding. Close monitoring is often required [1.2.1].
Digoxin: Lansoprazole can increase the levels of this heart medication in your blood, raising the risk of side effects [1.2.1].
Methotrexate: When taken with lansoprazole, levels of methotrexate, a drug for rheumatoid arthritis and psoriasis, can increase, leading to potential toxicity [1.2.1].
Clopidogrel: This antiplatelet medication's effectiveness may be reduced [1.2.1].
Phenytoin: An epilepsy medication whose levels can be affected by lansoprazole [1.2.1].
Sucralfate: This medication, used for ulcers, can hinder the absorption of lansoprazole. It is recommended to take lansoprazole at least 30 minutes before sucralfate [1.8.4, 1.9.1].

Comparison of Key Drug Interactions


Drug Class	Example(s)	Type of Interaction	Potential Consequence
Blood Thinners	Warfarin, Clopidogrel	Metabolic Interference	Altered effectiveness, increased risk of bleeding or clotting [1.2.1].
Heart Medications	Digoxin	Increased Absorption	Higher risk of digoxin toxicity [1.2.1].
Antifungals	Ketoconazole, Itraconazole	Reduced Absorption	Decreased effectiveness of the antifungal medication [1.8.4].
Certain Antibiotics	Rifampicin	Increased Metabolism of Lansoprazole	Decreased effectiveness of lansoprazole [1.2.1].
HIV Protease Inhibitors	Atazanavir, Nelfinavir	Reduced Absorption	Reduced antiviral effect [1.2.4].
Immunosuppressants	Methotrexate, Mycophenolate Mofetil	Increased Drug Levels or Reduced Absorption	Increased toxicity (Methotrexate) or reduced effectiveness (MMF) [1.2.1, 1.8.4].

Herbal Supplements and Over-the-Counter Products

Interactions are not limited to prescription drugs. Common supplements can also cause problems.

St. John's Wort: This herbal remedy for depression should not be taken with lansoprazole. It can speed up the breakdown of lansoprazole in the body, making it less effective [1.9.5, 1.8.2].
Iron and Vitamin B12: As mentioned, lansoprazole can reduce the absorption of iron [1.8.1]. Long-term use (over three years) can also lead to a deficiency in Vitamin B12 because its absorption from food is acid-dependent [1.8.4, 1.9.2].

Food and Alcohol Considerations

For maximum effectiveness, lansoprazole should be taken on an empty stomach, at least 30 to 60 minutes before a meal [1.3.3, 1.9.5]. Food can reduce the amount of lansoprazole absorbed by the body by up to 50-70%, decreasing its acid-reducing effects [1.3.3, 1.6.3].

While there is no direct, major interaction between lansoprazole and alcohol, alcohol itself can increase stomach acid production and worsen the symptoms of acid reflux or indigestion [1.4.2, 1.3.2]. It can also exacerbate side effects like dizziness [1.4.5]. Therefore, it is generally best to avoid or limit alcohol intake while being treated for acid-related conditions [1.3.4].

Conclusion: Prioritize Communication with Your Doctor

Lansoprazole is a powerful tool for managing acid-related stomach conditions, but its effectiveness is highly dependent on how it is taken. Mixing it with certain drugs, supplements, or even taking it with food can lead to reduced efficacy or an increased risk of adverse effects. Always maintain an open dialogue with your healthcare provider and pharmacist, informing them of everything you take—from prescription medications to herbal supplements—to create a safe and effective treatment plan [1.9.1].

For more detailed information from a primary source, you can visit the MedlinePlus page on Lansoprazole.

Frequently Asked Questions

It is best to take lansoprazole with water on an empty stomach, at least 30 minutes before food or drink. Coffee can be acidic and may worsen your symptoms, and food or other drinks can reduce the drug's effectiveness [1.3.2, 1.3.3].

Lansoprazole is often prescribed in combination with antibiotics, including amoxicillin and clarithromycin, to treat stomach ulcers caused by H. pylori bacteria. This is a standard and effective treatment regimen [1.5.4].

Yes, it is generally safe to take painkillers such as paracetamol or ibuprofen with lansoprazole. In fact, lansoprazole is sometimes prescribed to prevent ulcers that can be caused by nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen [1.9.5, 1.5.3].

You should avoid foods that can trigger your acid reflux symptoms, such as spicy foods, tomatoes, chocolate, peppermint, and fatty or fried foods. These don't directly interact with the drug but can worsen the condition it's treating [1.3.2].

Yes, you can take an antacid with lansoprazole if you need immediate relief from symptoms while waiting for the lansoprazole to take full effect, which can be a few days [1.9.5].

Long-term use (more than a year) may increase the risk of bone fractures, Vitamin B12 deficiency, and low magnesium levels in your blood. Your doctor will monitor your health if you need to take it for an extended period [1.9.5, 1.10.4].

St. John's wort is an herbal supplement that can interfere with how your body processes lansoprazole, making the medication less effective at reducing stomach acid [1.9.5, 1.8.4].

If you suspect an interaction or experience unusual side effects such as severe diarrhea, dizziness, or muscle cramps, contact your doctor or pharmacist immediately for advice. Do not stop taking any medication without consulting them first [1.10.2, 1.9.1].