Hydroxyzine Hydrochloride Brillpharma (Ireland) (Hydroxyzine Hydrochloride)

Hydroxyzine hydrochloride is a first‑generation H1 antihistamine that addresses allergic and anxiety‑related conditions.

• Allergic skin conditions (e.g., urticaria, pruritus): reduces itching and hives by blocking histamine receptors.
• Anxiety and tension: provides a calming effect through central H1 antagonism.
• Pre‑operative or post‑operative sedation: induces sedation to facilitate surgical procedures.
• Prevention of nausea and vomiting: mitigates emesis by antihistaminic and anticholinergic actions.

• Hydroxyzine hydrochloride acts as a selective antagonist of peripheral and central histamine H1 receptors, preventing histamine‑mediated responses such as vasodilation, increased vascular permeability, and neuronal excitation. Its anticholinergic activity further contributes to sedation and antiemetic effects, while central H1 blockade produces anxiolytic and sedative properties. The drug readily crosses the blood‑brain barrier, allowing central nervous system effects, and its high affinity for H1 receptors results in prolonged receptor occupancy, accounting for its lasting therapeutic action.

Hydroxyzine hydrochloride may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Drowsiness: mild to moderate sedation.
• Dry mouth: reduced salivation.
• Dizziness: light‑headed sensation.
• Blurred vision: temporary visual disturbance.
• Constipation: slowed gastrointestinal motility.
• Headache: mild cranial pain.

Serious or Rare Side Effects

• Cardiac arrhythmia: irregular heart rhythm.
• Severe hypotension: marked drop in blood pressure.
• Hepatotoxicity: liver enzyme elevation or injury.
• Extrapyramidal symptoms: involuntary muscle movements.
• Anaphylaxis: severe allergic reaction.
• Seizures: rare convulsive episodes.

When prescribing hydroxyzine hydrochloride, clinicians should consider several safety measures.

• Assess patient history: evaluate for glaucoma, urinary retention, or prostatic hypertrophy before use.
• Monitor CNS effects: caution in patients prone to excessive sedation or dizziness.
• Avoid in elderly: increased risk of falls and anticholinergic burden.
• Use with caution in hepatic impairment: dose adjustment may be required.
• Drug‑interaction review: check concurrent use of CNS depressants, antihistamines, or MAO inhibitors.
• Store at ambient temperature: keep below 25 °C in original packaging, protect from moisture and light.

Hydroxyzine hydrochloride can interact with several medicines, altering its efficacy or safety.

Major Interactions (Avoid)

• CNS depressants (e.g., benzodiazepines, opioids): may cause profound sedation or respiratory depression.
• MAO inhibitors: increase risk of hypertensive crisis and severe sedation.
• Anticholinergic agents: additive anticholinergic effects leading to confusion or urinary retention.

Moderate Interactions (Monitor Closely)

• Alcohol: enhances drowsiness and impairment.
• Other antihistamines: may increase sedation and anticholinergic load.
• QT‑prolonging drugs: potential additive effect on cardiac repolarization.
• CYP3A4 inhibitors (e.g., ketoconazole): may raise hydroxyzine plasma levels.