Drug interactions
Formoterol + Timolol
Severity: Major
Formoterol and Timolol: major interaction.
Last updated Sources: US FDA label
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
Timolol is a nonselective beta-blocker, and even ophthalmic doses can be absorbed enough to block beta-2 receptors, reducing formoterol's effect and possibly triggering bronchospasm in asthma or COPD. Oral timolol carries a greater risk.
What this interaction means in plain words
Formoterol and Timolol can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Formoterol belongs to Respiratory; Timolol belongs to Cardiovascular.
Why it happens
Pharmacodynamic antagonism at beta-2 adrenergic receptors.
What to do
Avoid timolol in patients with asthma or bronchospastic COPD and choose an alternative such as a prostaglandin analogue for glaucoma. If unavoidable, monitor respiratory status closely.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
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 Timolol
- Acebutolol + Timolol Major
- Aldesleukin + Timolol Major
- Amifostine + Timolol Major
- Amiodarone + Timolol Major
- Arformoterol + Timolol Major
- Atenolol-chlorthalidone + Timolol Major
Frequently asked questions
Can I take Formoterol with Timolol?
MediHelp rates the interaction as major. Formoterol and Timolol can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Timolol is a nonselective beta-blocker, and even ophthalmic doses can be absorbed enough to block beta-2 receptors, reducing formoterol's effect and possibly triggering bronchospasm in asthma or COPD. Oral timolol carries a greater risk.
How serious is the interaction between Formoterol and Timolol?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid timolol in patients with asthma or bronchospastic COPD and choose an alternative such as a prostaglandin analogue for glaucoma. If unavoidable, monitor respiratory status closely.
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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