Paroxetine (Paxil) + Cetirizine/Pseudoephedrine (Zyrtec-D): Interaction Profile

No major pharmacokinetic interaction between paroxetine (SSRI) and cetirizine/pseudoephedrine. However, additive CNS effects may occur:

• Serotonin syndrome risk: Theoretical (pseudoephedrine has weak serotonergic activity); monitor for hyperreflexia, clonus, hyperthermia.
• Cardiovascular: Pseudoephedrine ↑ BP/HR; paroxetine minimal cardiac effect but caution in hypertension.
• CNS: Both can cause insomnia, nervousness, dizziness.

Practical Advice

• Use short-term only for nasal congestion.
• Monitor BP if hypertensive.
• Report unusual agitation, tremor, fever.
• Consider non-drug alternatives (saline irrigation, intranasal corticosteroids).

Always inform prescriber of all OTC medications.