Drug interactions
Formoterol-mometasone + Metolazone
Severity: Moderate
Formoterol-mometasone and Metolazone: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Both formoterol and metolazone can lower serum potassium. Combined use may cause clinically significant hypokalemia, which raises the risk of arrhythmias, especially in patients with heart disease or on other QT-prolonging drugs.
What this interaction means in plain words
Formoterol-mometasone and Metolazone can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Formoterol-mometasone belongs to Respiratory; Metolazone belongs to Cardiovascular.
Why it happens
Additive hypokalemia from beta2-agonist-driven intracellular potassium shift and diuretic-induced renal potassium loss.
What to do
Check serum potassium and magnesium at baseline and periodically, and replace or add a potassium-sparing agent as needed. Take extra care in patients with cardiac disease or on high doses of formoterol.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Formoterol-mometasone
Other interactions of Metolazone
Frequently asked questions
Can I take Formoterol-mometasone with Metolazone?
MediHelp rates the interaction as moderate. Formoterol-mometasone and Metolazone can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Both formoterol and metolazone can lower serum potassium. Combined use may cause clinically significant hypokalemia, which raises the risk of arrhythmias, especially in patients with heart disease or on other QT-prolonging drugs.
How serious is the interaction between Formoterol-mometasone and Metolazone?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check serum potassium and magnesium at baseline and periodically, and replace or add a potassium-sparing agent as needed. Take extra care in patients with cardiac disease or on high doses of formoterol.
What other medicines interact with Formoterol-mometasone?
MediHelp also lists interactions of Formoterol-mometasone with, for example, Amiodarone, Amisulpride, Amoxapine. The full list is on the Formoterol-mometasone page.
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