Drug interactions
Carbidopa + Doxazosin
Severity: Moderate
Carbidopa and Doxazosin: 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
Carbidopa is given with levodopa, and the levodopa-derived dopamine can lower blood pressure and cause orthostatic hypotension. With doxazosin, which also causes postural hypotension, the effects may be additive. Carbidopa alone has little hypotensive action.
What this interaction means in plain words
Carbidopa and Doxazosin 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.
Carbidopa belongs to Central Nervous System; Doxazosin belongs to Genitourinary.
Why it happens
Additive hypotensive effects: alpha-1 blockade by doxazosin plus dopaminergic vasodilation and autonomic effects from levodopa therapy.
What to do
Check standing and sitting blood pressure when starting or adjusting levodopa/carbidopa. Reduce doxazosin dose if symptomatic orthostasis 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 Doxazosin
- Alfuzosin + Doxazosin Major
- Amifostine + Doxazosin Major
- Avanafil + Doxazosin Major
- Doxazosin + Dutasteride-tamsulosin Major
- Doxazosin + Phentolamine Major
- Doxazosin + Prazosin Major
Other interactions of Carbidopa
Frequently asked questions
Can I take Carbidopa with Doxazosin?
MediHelp rates the interaction as moderate. Carbidopa and Doxazosin 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. Carbidopa is given with levodopa, and the levodopa-derived dopamine can lower blood pressure and cause orthostatic hypotension. With doxazosin, which also causes postural hypotension, the effects may be additive. Carbidopa alone has little hypotensive action.
How serious is the interaction between Carbidopa and Doxazosin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check standing and sitting blood pressure when starting or adjusting levodopa/carbidopa. Reduce doxazosin dose if symptomatic orthostasis occurs.
What other medicines interact with Doxazosin?
MediHelp also lists interactions of Doxazosin with, for example, Alfuzosin, Amifostine, Avanafil. The full list is on the Doxazosin page.
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