Drug interactions
Cetirizine + Theophylline
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.
Overview
Theophylline (400 mg/day) modestly reduces cetirizine clearance (~16%), potentially increasing cetirizine exposure; no meaningful effect on theophylline levels.
Mechanism of action
Pharmacokinetic—reduced cetirizine clearance with theophylline; precise mechanism not fully defined.
Clinical management
No routine dose adjustment needed; monitor for increased cetirizine adverse effects (e.g., somnolence). If symptomatic, consider dose reduction.
Drug reference
References
- Zyrtec (cetirizine) Prescribing Information – Drug Interactions — FDA Label
Frequently asked questions
Can I take Cetirizine with Theophylline?
The interaction is rated: Minor. Theophylline (400 mg/day) modestly reduces cetirizine clearance (~16%), potentially increasing cetirizine exposure; no meaningful effect on theophylline levels.
How serious is the interaction between Cetirizine and Theophylline?
The interaction is rated: Minor. Evidence level: High.
How is the interaction between Cetirizine and Theophylline managed?
No routine dose adjustment needed; monitor for increased cetirizine adverse effects (e.g., somnolence). If symptomatic, consider dose reduction.
Why do Cetirizine and Theophylline interact?
Pharmacokinetic—reduced cetirizine clearance with theophylline; precise mechanism not fully defined.
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