Phenylephrine and Terazosin Interaction
Drug interaction information between Phenylephrine and Terazosin.
Phenylephrine and Terazosin have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Phenylephrine and Terazosin. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
These drugs work against each other because one relaxes blood vessels to lower blood pressure while the other narrows them to raise it. This can make your blood pressure medicine less effective.
FDA Label Information
Terazosin has been used concomitantly in at least 50 patients on the following drugs or drug classes: analgesic/anti-inflammatory (e.g., acetaminophen, aspirin, codeine, ibuprofen, indomethacin); antibiotics (e.g., erythromycin, trimethoprim and sulfamethoxazole); anticholinergic/sympathomimetics (e.g., phenylephrine hydrochloride, phenylpropanolamine hydrochloride, pseudoephedrine hydrochloride); antigout (e.g., allopurinol); antihistamines (e.g., chlorpheniramine); cardiovascular agents (e.g., atenolol, hydrochlorothiazide, methyclothiazide, propranolol); corticosteroids;...
Terazosin Also Interacts With
- Hydrochlorothiazide minor
- Ibuprofen minor
- Allopurinol minor
- Aspirin minor
- Atenolol minor
Frequently Asked Questions
What SPL severity band is on file for Phenylephrine + Terazosin?
Compiled FDA labeling labels this pair minor. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Terazosin has 15 labeled pairs on file vs Phenylephrine's 2. In the minor band specifically: Phenylephrine has 1; Terazosin has 15 (also Hydrochlorothiazide, Ibuprofen, Allopurinol, Aspirin).
What mechanism field is on file for Phenylephrine and Terazosin?
These drugs work against each other because one relaxes blood vessels to lower blood pressure while the other narrows them to raise it. This can make your blood pressure medicine less effective.
Phenylephrine carries more major-labeled pairs than Terazosin
SPL source-record counts only. This page's band is minor · classes on file: Phenylephrine (Alpha-1 Agonist); Terazosin (Alpha-1 Blocker).
Phenylephrine has 1 major-labeled pair vs Terazosin's 0. This page itself is in the minor band, not the major band.
1 major · 0 moderate · 1 minor · 2 total
Phenylephrine has no other minor-band peer in this dataset besides Terazosin.
0 major · 0 moderate · 15 minor · 15 total
- Other minor peers for Terazosin
- Hydrochlorothiazide
- Ibuprofen
- Allopurinol
- Aspirin
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.