Levocetirizine Dihydrochloride Bristol Laboratories (Levocetirizine Dihydrochloride)

• Levocetirizine Dihydrochloride is a second‑generation antihistamine that targets histamine‑mediated allergic conditions.
• Allergic rhinitis: alleviates nasal congestion, sneezing, itching and rhinorrhea.
• Chronic idiopathic urticaria: reduces frequency and severity of hives and associated itching.
• Allergic conjunctivitis: relieves eye itching, redness and tearing caused by allergens.

• Levocetirizine Dihydrochloride selectively blocks peripheral histamine H1 receptors, preventing histamine from binding to these sites on mast cells, basophils and sensory nerves. By inhibiting this receptor activation, it diminishes the vascular permeability, edema, and sensory nerve stimulation that underlie the classic symptoms of allergic reactions, while sparing central nervous system H1 receptors, which reduces sedation significantly.

Levocetirizine Dihydrochloride may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Drowsiness: mild sedation that may affect alertness.
• Headache: transient cranial discomfort.
• Dry mouth: reduced salivary flow.
• Fatigue: generalized tiredness.

Serious or Rare Side Effects

• Angioedema: swelling of face, lips or airway requiring urgent care.
• Anaphylactic reaction: severe, potentially life‑threatening hypersensitivity.
• Severe skin rash: including Stevens‑Johnson syndrome or toxic epidermal necrolysis.

• When prescribing Levocetirizine Dihydrochloride, clinicians should observe the following precautions to ensure safe use.
• Assess renal function: dose adjustment may be required in severe renal impairment.
• Monitor hepatic status: use with caution in patients with liver disease.
• Avoid operating machinery: drowsiness can impair psychomotor performance.
• Observe for hypersensitivity: discontinue if signs of rash, swelling or breathing difficulty appear.
• Pregnancy and lactation: only use if benefit outweighs potential risk to fetus or infant.
• Store below 25°C: keep in the original pack, protect from moisture.

Levocetirizine Dihydrochloride can interact with other medicines; awareness of major and moderate interactions helps prevent adverse outcomes.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, ritonavir): may increase levocetirizine plasma concentrations.
• Alcohol: combined use can enhance sedation and impair cognition.

Moderate Interactions (Monitor Closely)

• CNS depressants (e.g., benzodiazepines, opioids): additive drowsiness.
• Other antihistamines: may increase risk of anticholinergic effects.
• Diuretics (e.g., thiazides): may raise levocetirizine levels.