Drug interactions
Carbamazepine + Guanfacine
Severity: Moderate
Carbamazepine 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
Carbamazepine substantially lowers guanfacine concentrations and shortens its half-life, which may lead to loss of blood pressure or ADHD symptom control.
What this interaction means in plain words
Carbamazepine 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.
Carbamazepine belongs to Central Nervous System; Guanfacine belongs to Cardiovascular.
Why it happens
Carbamazepine induces CYP3A4, increasing guanfacine metabolism.
What to do
Monitor blood pressure and clinical response; consider doubling the extended-release guanfacine dose in ADHD or dosing immediate-release more often. Reduce the dose if carbamazepine is stopped.
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 Carbamazepine
- Artemether / lumefantrine + Carbamazepine Contraindicated
- Cabotegravir + Carbamazepine Contraindicated
- Carbamazepine + Delamanid Contraindicated
- Carbamazepine + Dienogest / estradiol valerate Contraindicated
- Carbamazepine + Doravirine Contraindicated
- Carbamazepine + Elbasvir / grazoprevir Contraindicated
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 Carbamazepine with Guanfacine?
MediHelp rates the interaction as moderate. Carbamazepine 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. Carbamazepine substantially lowers guanfacine concentrations and shortens its half-life, which may lead to loss of blood pressure or ADHD symptom control.
How serious is the interaction between Carbamazepine 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 blood pressure and clinical response; consider doubling the extended-release guanfacine dose in ADHD or dosing immediate-release more often. Reduce the dose if carbamazepine is stopped.
What other medicines interact with Carbamazepine?
MediHelp also lists interactions of Carbamazepine with, for example, Artemether / lumefantrine, Cabotegravir, Delamanid. The full list is on the Carbamazepine page.
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