Metaproterenol and Formoterol: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Metaproterenol
Formoterol
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
An increased risk of clinically significant cardiovascular effects and fatalities
Interaction Deep Dive
Exert caution when formoterol is coadministered with beta-2 agonists as it may increase risk of sympathetic effects of formoterol and clinically significant cardiovascular effects and fatalities12.
Why it happens (mechanism)
Additive effects
Common questions
Can I take Metaproterenol and Formoterol together?
An increased risk of clinically significant cardiovascular effects and fatalities Always confirm with your pharmacist or prescriber before making any change.
How serious is the Metaproterenol and Formoterol interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Metaproterenol or Formoterol need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (2)
- Product Information: BREZTRI AEROSPHERE® inhalation aerosol, budesonide, glycopyrrolate, formoterol fumarate inhalation aerosol. AstraZeneca Pharmaceuticals LP, Wilmington, DE, 2026. DailyMed
- Product Information: SYMBICORT AEROSPHERE® oral inhalation aerosol, budesonide formoterol fumarate oral inhalation aerosol. AstraZeneca Pharmaceuticals LP, Wilmington, DE, 2026.
Keep reading about Metaproterenol
Keep reading about Formoterol
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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