Drug interactions
Formoterol + Metolazone
Severity: Moderate
Formoterol 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 agents can lower serum potassium, and the combination may produce clinically significant hypokalemia. This raises the risk of arrhythmias, particularly in patients with cardiac disease or other QT-prolonging drugs.
What this interaction means in plain words
Formoterol 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 belongs to Respiratory; Metolazone belongs to Cardiovascular.
Why it happens
Additive hypokalemia from beta-2-mediated intracellular potassium shift and thiazide-like diuretic renal potassium loss.
What to do
Monitor serum potassium and magnesium periodically and replace as needed. Take extra care in patients with severe asthma or COPD, where hypoxia increases the risk.
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
- Adagrasib + Formoterol Major
- Amiodarone + Formoterol Major
- Amisulpride + Formoterol Major
- Amitriptyline + Formoterol Major
- Amoxapine + Formoterol Major
- Arformoterol + Formoterol Major
Other interactions of Metolazone
Frequently asked questions
Can I take Formoterol with Metolazone?
MediHelp rates the interaction as moderate. Formoterol 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 agents can lower serum potassium, and the combination may produce clinically significant hypokalemia. This raises the risk of arrhythmias, particularly in patients with cardiac disease or other QT-prolonging drugs.
How serious is the interaction between Formoterol 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: Monitor serum potassium and magnesium periodically and replace as needed. Take extra care in patients with severe asthma or COPD, where hypoxia increases the risk.
What other medicines interact with Formoterol?
MediHelp also lists interactions of Formoterol with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Formoterol page.
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