Drug interactions
Guanfacine + Tadalafil
Severity: Moderate
Guanfacine and Tadalafil: 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 lowers blood pressure through central action, and tadalafil adds vasodilation, so additive hypotension may occur.
What this interaction means in plain words
Guanfacine and Tadalafil 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; Tadalafil belongs to Genitourinary.
Why it happens
Additive hypotensive effects of central alpha-2 agonism and PDE5 inhibition.
What to do
Monitor blood pressure and orthostatic symptoms when starting or adjusting either drug. Counsel patients to rise slowly.
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 Tadalafil
- Amyl nitrite + Tadalafil Contraindicated
- Isosorbide dinitrate + Tadalafil Contraindicated
- Isosorbide mononitrate + Tadalafil Contraindicated
- Nitroglycerin po + Tadalafil Contraindicated
- Nitroglycerin rectal + Tadalafil Contraindicated
- Nitroglycerin sublingual + Tadalafil 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 Guanfacine with Tadalafil?
MediHelp rates the interaction as moderate. Guanfacine and Tadalafil 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 lowers blood pressure through central action, and tadalafil adds vasodilation, so additive hypotension may occur.
How serious is the interaction between Guanfacine and Tadalafil?
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 orthostatic symptoms when starting or adjusting either drug. Counsel patients to rise slowly.
What other medicines interact with Tadalafil?
MediHelp also lists interactions of Tadalafil with, for example, Amyl nitrite, Isosorbide dinitrate, Isosorbide mononitrate. The full list is on the Tadalafil page.
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