Levocetirizin Ab (Levocetirizine Dihydrochloride)

Levocetirizine is a selective peripheral H1‑receptor antagonist used to manage allergic conditions.

• Allergic rhinitis: reduces nasal congestion, sneezing, itching and watery discharge.
• Seasonal allergic rhinitis: alleviates symptoms triggered by pollen or outdoor allergens.
• Chronic idiopathic urticaria: diminishes the frequency and severity of hives and associated itching.

• Levocetirizine binds selectively to peripheral H1 receptors, blocking the action of endogenous histamine released during allergic reactions. By preventing histamine from activating these receptors, it reduces vasodilation, increased vascular permeability, and sensory nerve stimulation, thereby alleviating typical allergic symptoms such as itching, swelling, and rhinorrhea.

Levocetirizine is generally well tolerated, but adverse reactions can occur.

Common Side Effects

• Drowsiness: mild to moderate sedation, especially at the start of therapy.
• Headache: transient, often resolves without intervention.
• Dry mouth: reduced salivation causing mild discomfort.
• Fatigue: feeling of tiredness that may improve with continued use.
• Nausea: occasional stomach upset.

Serious or Rare Side Effects

• Angioedema: swelling of face, lips, tongue requiring urgent care.
• Severe skin reactions: such as Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Anaphylaxis: rare systemic allergic response with respiratory compromise.
• Thrombocytopenia: low platelet count, may present with easy bruising.
• Hepatic injury: abnormal liver function tests, monitor if symptoms arise.

Before initiating Levocetirizin Ab, consider the following safety measures.

• Renal impairment: adjust dose or monitor closely in patients with reduced kidney function.
• Hypersensitivity: discontinue if signs of allergic reaction to levocetirizine occur.
• Concomitant CNS depressants: use caution as combined sedation may increase.
• Elderly patients: start with the lowest effective dose due to increased sensitivity.
• Alcohol consumption: limit intake to reduce additive drowsiness.
• Store at ambient temperature: keep below 25 °C, retain in original packaging, protect from moisture.

Levocetirizin Ab may interact with other medicines; awareness helps prevent adverse outcomes.

Major Interactions (Avoid)

• Other H1 antihistamines: additive sedation and reduced efficacy.
• Alcohol or CNS depressants: heightened drowsiness and impaired coordination.

Moderate Interactions (Monitor Closely)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, ritonavir): may increase plasma concentrations.
• Theophylline: potential for altered theophylline levels.
• Anticholinergic agents: may exacerbate dry mouth.
• Diuretics: monitor for changes in electrolyte balance.