Drug interactions
Guanfacine + Timolol
Severity: Moderate
Guanfacine and Timolol: 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
Guanfacine and timolol both lower heart rate and blood pressure, so bradycardia and hypotension may be additive. If guanfacine is stopped while a beta-blocker continues, rebound hypertension can be worsened because of unopposed alpha stimulation.
What this interaction means in plain words
Guanfacine and Timolol 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.
Guanfacine belongs to Cardiovascular; Timolol belongs to Cardiovascular.
Why it happens
Additive sympatholytic effects from central alpha-2 agonism and beta-adrenergic blockade, with exaggerated rebound after alpha-agonist withdrawal.
What to do
Monitor heart rate and blood pressure. If guanfacine is to be stopped, taper it gradually and consider withdrawing the beta-blocker first.
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 Timolol
- Acebutolol + Timolol Major
- Aldesleukin + Timolol Major
- Amifostine + Timolol Major
- Amiodarone + Timolol Major
- Arformoterol + Timolol Major
- Atenolol-chlorthalidone + Timolol Major
Other interactions of Guanfacine
- Clonidine + Guanfacine Major
- Guanfacine + Lofexidine Major
- Aldesleukin + Guanfacine Moderate
- Amiodarone + Guanfacine Moderate
- Amisulpride + Guanfacine Moderate
- Amitriptyline + Guanfacine Moderate
Frequently asked questions
Can I take Guanfacine with Timolol?
MediHelp rates the interaction as moderate. Guanfacine and Timolol 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. Guanfacine and timolol both lower heart rate and blood pressure, so bradycardia and hypotension may be additive. If guanfacine is stopped while a beta-blocker continues, rebound hypertension can be worsened because of unopposed alpha stimulation.
How serious is the interaction between Guanfacine and Timolol?
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 heart rate and blood pressure. If guanfacine is to be stopped, taper it gradually and consider withdrawing the beta-blocker first.
What other medicines interact with Timolol?
MediHelp also lists interactions of Timolol with, for example, Acebutolol, Aldesleukin, Amifostine. The full list is on the Timolol page.
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