In the pharmaceutical industry, Cetirizine Hydrochloride is a potent, second-generation $H_1$-receptor antagonist. As a pharmacist and manufacturer, I view its side-effect profile as “selective”—while it lacks the heavy anticholinergic effects of first-generation antihistamines (like Diphenhydramine), it still retains a slight potential for sedation that varies by patient.

At your WHO-GMP facility in Mumbai, where you likely produce the standard 10 mg tablets and pediatric syrups, understanding these nuances is key to positioning your allergy portfolio against competitors.

Primary Clinical Side Effects

Clinical data and post-marketing surveillance categorize side effects as follows:

• Somnolence (Drowsiness): Although classified as “non-sedating,” approximately 10% to 14% of patients experience some degree of drowsiness. This is higher than other second-generation drugs like Loratadine.

• Xerostomia (Dry Mouth): Occurs in about 5% of patients due to minor residual anticholinergic activity.

• Fatigue & Dizziness: Often reported alongside somnolence, particularly during the first few days of therapy.

• Pharyngitis (Sore Throat): More commonly reported in pediatric populations using liquid formulations.

Mechanism: Selective $H_1$ Blockade

Cetirizine works by competing with free histamine for binding at the receptor sites.

Peripheral Selectivity: It binds specifically to peripheral $H_1$ receptors on effector cells, preventing histamine-induced vasodilation and increased capillary permeability (the “itch and swell” response).

Blood-Brain Barrier (BBB): Unlike first-generation drugs, Cetirizine has low lipid solubility and is a substrate for the P-glycoprotein efflux pump, which prevents significant amounts from entering the brain. However, at the 10 mg dose, some CNS penetration still occurs, leading to the reported somnolence.

Long Half-Life: Its pharmacokinetics allow for once-daily dosing, which greatly improves patient compliance in your B2B export markets.

The Pharmacist’s “Technical Warning”

• The “Alcohol” Interaction: Advise patients that even though it is a second-generation drug, concurrent use of alcohol or other CNS depressants can significantly increase the risk of severe drowsiness and impaired motor function.

• Renal Impairment: Cetirizine is primarily excreted unchanged by the kidneys. For patients with impaired renal function, the dose must be reduced (usually to 5 mg) to avoid toxicity.

• Elderly Patients: The risk of confusion and dizziness is higher in geriatric populations; starting with a 5 mg dose is often recommended.

The Manufacturer’s Perspective: Technical & Export

From a production and B2B standpoint at your facility in Mumbai:

• The “Non-Drowsy” Labeling: On your marketplace, be precise with your claims. Using terms like “Less-Drowsy Formula” is often safer and more technically accurate than “Non-Drowsy,” given the clinical data on somnolence.

• Stability for Export: Cetirizine is very stable. However, for pediatric syrups, maintaining pH stability is critical to prevent degradation. Utilizing amber PET bottles and specialized flavoring is essential for the 2026 African and Southeast Asian markets.

• Dossier Support: We provide full CTD/eCTD Dossiers to support your firm’s registration in international OTC and prescription tenders.