Drug interactions
Fentanyl + Guanfacine
Severity: Moderate
Fentanyl and Guanfacine: 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 commonly causes somnolence, fatigue and hypotension, which may add to the sedation and hypotensive effects of fentanyl. Patients may experience excessive drowsiness and dizziness.
What this interaction means in plain words
Fentanyl and Guanfacine 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.
Fentanyl belongs to Musculoskeletal; Guanfacine belongs to Cardiovascular.
Why it happens
Additive CNS depression and hypotension via central alpha-2 agonism combined with opioid effects.
What to do
Monitor sedation and blood pressure and counsel on rising slowly. Reduce doses if excessive drowsiness occurs.
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 Fentanyl
- Alvimopan + Fentanyl Contraindicated
- Fentanyl + Isocarboxazid Contraindicated
- Fentanyl + Olanzapine / samidorphan Contraindicated
- Fentanyl + Phenelzine Contraindicated
- Fentanyl + Tranylcypromine Contraindicated
- Alfentanil + Fentanyl 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 Fentanyl with Guanfacine?
MediHelp rates the interaction as moderate. Fentanyl and Guanfacine 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 commonly causes somnolence, fatigue and hypotension, which may add to the sedation and hypotensive effects of fentanyl. Patients may experience excessive drowsiness and dizziness.
How serious is the interaction between Fentanyl and Guanfacine?
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 sedation and blood pressure and counsel on rising slowly. Reduce doses if excessive drowsiness occurs.
What other medicines interact with Fentanyl?
MediHelp also lists interactions of Fentanyl with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Fentanyl page.
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