Terfenadine has 10 known drug interactions based on U.S. FDA drug labeling data. Of these, 1 are contraindicated combinations that should be avoided entirely. 1 are classified as major interactions requiring close medical supervision. Notable interactions include combinations with Clarithromycin, Erythromycin Lactobionate, Azithromycin. Patients taking Terfenadine should inform their healthcare provider of all current medications — including over-the-counter drugs and supplements — to avoid potentially harmful combinations. Data sourced from OpenFDA and the NIH National Library of Medicine.
- Total
- 10
- Contraindicated
- 1
- Major
- 1
- Moderate
- 5
- Minor
- 2
Contraindicated (1)
- Terfenadine + Clarithromycin— Concomitant administration is contraindicated. Clarithromycin increases plasma concentrations of terfenadine's active ac…
Major (1)
- Terfenadine + Erythromycin Lactobionate— Erythromycin significantly alters metabolism of this nonsedating antihistamine; rare serious cardiovascular adverse even…
Moderate (5)
- Terfenadine + Azithromycin— Macrolide products including azithromycin may increase terfenadine concentrations. Careful monitoring is advised.
- Terfenadine + Carbamazepine— CYP3A4 inhibitor that increases carbamazepine plasma levels; close monitoring and dosage adjustment may be required.
- Terfenadine + Dermatophagoides Farinae— Second-generation antihistamine that suppresses histamine skin test reactions and could mask positive response. Avoid sk…
- Terfenadine + Lanreotide Acetate— Lanreotide may decrease metabolic clearance of terfenadine; avoid concomitant use or consider dose reduction.
- Terfenadine + Octreotide Acetate— Octreotide may decrease metabolic clearance of terfenadine through CYP3A4 suppression; use with caution due to low thera…
Minor (2)
- Terfenadine + Montelukast— No dose adjustment needed when co-administered with montelukast sodium.
- Terfenadine + Montelukast Sodium— No dose adjustment needed when co-administered with montelukast sodium.