Can I take Flecainide and Mirabegron together?

Why this happens

Mirabegron can slow down the action of a specific enzyme in the liver (called CYP2D6) that is responsible for breaking down flecainide. Because the flecainide is broken down more slowly, it can build up to higher levels in your body.

What you should do

You should speak to your doctor before taking these medicines together. Your doctor may need to adjust your dose of flecainide or monitor your heart rhythm more closely using an ECG (electrocardiogram). If you experience any new palpitations, fainting, or shortness of breath, seek medical advice immediately.

Important precautions

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 uncontrolled high blood pressure

Do not take mirabegron if your blood pressure is very high (180/110 mmHg or higher). It can cause a dangerous further increase in blood pressure and requires regular monitoring during treatment.

Food and drink warnings

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 mirabegron. Alcohol can irritate the bladder and increase urine production, which may counteract the benefits of your treatment. Additionally, both alcohol and mirabegron can affect your blood pressure; combining them may increase the risk of dizziness or lightheadedness.

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.

Mirabegron is used to treat an overactive bladder. Caffeine is a natural diuretic and bladder irritant that can worsen the symptoms you are taking this medicine to treat (such as urgency and frequency). You should limit your intake of caffeinated drinks to help the medicine work effectively.

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.

Using other medicines

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.