Drug interactions
Prazosin + Terazosin
Severity: Major
Prazosin and Terazosin: major interaction.
Last updated Sources: US FDA label
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
Both are alpha-1 blockers, so using them together duplicates therapy and increases the risk of significant hypotension, dizziness and syncope without added benefit.
What this interaction means in plain words
Prazosin and Terazosin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Prazosin belongs to Genitourinary; Terazosin belongs to Genitourinary.
Why it happens
Additive alpha-1 adrenergic receptor blockade causing vasodilation.
What to do
Avoid combining two alpha-1 blockers; use a single agent at an appropriate dose. If a switch is made, stop one drug before starting the other and retitrate.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Terazosin
- Alfuzosin + Terazosin Major
- Amifostine + Terazosin Major
- Avanafil + Terazosin Major
- Doxazosin + Terazosin Major
- Dutasteride-tamsulosin + Terazosin Major
- Lofexidine + Terazosin Major
Other interactions of Prazosin
- Alfuzosin + Prazosin Major
- Amifostine + Prazosin Major
- Avanafil + Prazosin Major
- Doxazosin + Prazosin Major
- Dutasteride-tamsulosin + Prazosin Major
- Phenoxybenzamine + Prazosin Major
Frequently asked questions
Can I take Prazosin with Terazosin?
MediHelp rates the interaction as major. Prazosin and Terazosin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Both are alpha-1 blockers, so using them together duplicates therapy and increases the risk of significant hypotension, dizziness and syncope without added benefit.
How serious is the interaction between Prazosin and Terazosin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid combining two alpha-1 blockers; use a single agent at an appropriate dose. If a switch is made, stop one drug before starting the other and retitrate.
What other medicines interact with Terazosin?
MediHelp also lists interactions of Terazosin with, for example, Alfuzosin, Amifostine, Avanafil. The full list is on the Terazosin page.
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