Levocetirizine (Levocetirizine Dihydrochloride)

Levocetirizine is a second‑generation antihistamine used to manage allergic conditions by blocking H1 receptors.

• Allergic rhinitis (seasonal and perennial): reduces nasal congestion, sneezing, itching and rhinorrhea.
• Chronic idiopathic urticaria: decreases the frequency and severity of hives and associated itching.
• Histamine‑mediated skin itching: alleviates itching caused by histamine release in various dermatologic reactions.

• Levocetirizine acts as a selective peripheral H1‑receptor antagonist. By binding to the histamine H1 receptor on mast cells, basophils and sensory nerves, it prevents histamine from triggering vasodilation, increased vascular permeability and nerve stimulation, thereby reducing the clinical manifestations of allergic reactions while largely sparing central nervous system activity.

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

Common Side Effects

• Drowsiness: mild to moderate sleepiness, especially at treatment initiation.
• Dry mouth: reduced salivation leading to oral discomfort.
• Headache: transient cranial pain.
• Nausea: mild gastrointestinal upset.
• Altered taste: temporary metallic or bitter sensation.
• Fatigue: feeling of reduced energy.

Serious or Rare Side Effects

• Angioedema: swelling of face, lips or tongue requiring urgent care.
• Severe skin rash: including Stevens‑Johnson syndrome.
• Anaphylaxis: rapid onset of systemic allergic reaction.
• Hepatitis: signs of liver inflammation.
• Blood dyscrasias: unexplained bruising or low blood counts.

When prescribing Levocetirizine, consider the following safety measures.

• Pregnancy: safety not established; use only if clearly needed.
• Breastfeeding: unknown excretion; weigh potential risks and benefits.
• Renal impairment: dose may require adjustment in severe dysfunction.
• Elderly patients: monitor for increased sedation or confusion.
• Concomitant CNS depressants: avoid or use with caution due to additive drowsiness.
• Store at ambient temperature: keep in the original container, protect from moisture and light.

Levocetirizine may interact with other medicines; review patient medication lists.

Major Interactions (Avoid)

• Ketoconazole: can increase levocetirizine plasma concentrations.
• Ritonavir: may raise levocetirizine levels, enhancing side effects.
• Other antihistamines: additive sedation and anticholinergic effects.

Moderate Interactions (Monitor Closely)

• Alcohol: may potentiate drowsiness.
• CNS depressants (e.g., benzodiazepines): monitor for excessive sedation.
• Theophylline: may increase the risk of central nervous system side effects.