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Can I take Flecainide and Lansoprazole together?

Drug interaction guide

There is no known direct interaction between flecainide and lansoprazole. It is generally considered safe to take these two medications together.

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Why this happens

Lansoprazole is a proton pump inhibitor (PPI) used to reduce stomach acid, and flecainide is an anti-arrhythmic medicine used to treat heart rhythm problems. They are processed by different pathways in the liver and do not significantly affect each other's absorption or excretion.

You can continue to take both medications as prescribed by your doctor. However, always inform your healthcare provider if you notice any new symptoms, such as dizziness or a change in your heartbeat, as flecainide requires careful monitoring.

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Heart failure or previous heart attack

Flecainide must not be used if you have heart failure or have previously suffered a heart attack, as it can increase the risk of life-threatening heart rhythm problems.

Permanent atrial fibrillation

This medicine should not be used if you have long-standing (permanent) atrial fibrillation that has not been corrected, as it can paradoxically cause the heart rate to become dangerously fast.

Severe diarrhoea

If you develop severe or persistent watery diarrhoea while taking lansoprazole, contact your doctor immediately, as it is associated with an increased risk of Clostridium difficile infection.

Lupus (SLE) or skin reactions

Contact your doctor if you develop a skin rash, especially in areas exposed to the sun, as lansoprazole can cause a rare but serious autoimmune skin reaction.

Alcohol

It is best to avoid or strictly limit alcohol while taking flecainide. Alcohol can interfere with your heart rhythm and may increase the risk of side effects such as dizziness or blurred vision. Combining alcohol with heart medication can also put extra strain on your heart and liver.

It is best to avoid or strictly limit alcohol while taking lansoprazole. Alcohol increases the amount of acid your stomach produces, which can make your symptoms worse and counteract the effects of the medicine.

Caffeine (Coffee, tea, energy drinks, cola)

Caffeine is a stimulant that can increase your heart rate or cause irregular heart rhythms. Since flecainide is used to treat heart rhythm problems (arrhythmias), consuming high amounts of caffeine may counteract the effects of your medicine or make your condition worse. It is best to limit your intake of caffeine.

Dairy products (Milk)

In some cases, particularly in children or patients on a milk-based diet, high intake of milk can affect how flecainide is absorbed. However, for most adults, normal amounts of dairy are fine. If you are making a significant change to your dairy intake, discuss this with your doctor.

Low-salt (low-sodium) diets

A sudden change to a very low-salt diet or using salt substitutes can increase the levels of flecainide in your blood, which may lead to toxicity. Do not make major changes to your salt intake without consulting your doctor.

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Taking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.

Disclaimer

This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.

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Article history

The information on this page is written and peer reviewed by qualified clinicians.

  • 25 Jan 2026 | Originally published
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