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Non-sedating Antihistamine (H1 Antagonist — Second-generation) Pregnancy: Considered acceptable in pregnancy — most safety data among second-generation antihistamines. RCOG recommends loratadine or cetirizine in pregnancy.

Loratadine

Brand names: Clarityn, Benadryl Once A Day

Adult dose

Dose: Allergic rhinitis, urticaria: 10mg OD
Route: Oral
Frequency: Once daily
Max: 10mg OD
Second-generation antihistamine — minimal sedation, no anticholinergic effects, does not cross blood-brain barrier significantly. Once-daily dosing. Available OTC. No QTc prolongation (unlike terfenadine, its predecessor). Preferred antihistamine when patients need to drive or operate machinery.

Paediatric dose

Route: Oral
Frequency: Once daily
Max: 10mg OD
BNFc: 2–11 years (body weight <30kg): 5mg OD; (≥30kg): 10mg OD. 12–17 years: 10mg OD. Syrup available (5mg/5mL).

Dose adjustments

Renal

eGFR <30: increase dosing interval to alternate days (every 48h).

Hepatic

Hepatic impairment: increase dosing interval to every 48h — hepatically metabolised to active desloratadine.

Clinical pearls

  • Non-sedating at standard doses — suitable for patients who drive; cetirizine causes more sedation in some patients (individual variation)
  • Preferred over chlorphenamine for regular/daily use in allergic rhinitis — non-sedating and once-daily; chlorphenamine is better for acute severe urticaria or anaphylaxis (faster onset and more potent)
  • Metabolised to desloratadine (active) — desloratadine is available separately (Neoclarityn) with similar profile and may be slightly more potent
  • Available OTC without prescription — good first-line recommendation for hay fever season

Contraindications

  • Hypersensitivity to loratadine

Side effects

  • Headache (most common)
  • Drowsiness (minimal at standard dose)
  • Dry mouth (minimal anticholinergic effect)
  • Fatigue

Interactions

  • CYP3A4/CYP2D6 inhibitors (ketoconazole, erythromycin) — increase loratadine levels; avoid combination or monitor for sedation
  • Alcohol — may cause minor additive sedation

Monitoring

  • Symptom control (allergic rhinitis / urticaria)
  • No routine monitoring required

Reference: BNFc; BNF 90; NICE CG134 (Allergic Rhinitis). Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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