Skip to content
ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Non-sedating H1 antihistamine Pregnancy: Large amount of data (>1000 exposed outcomes) indicate no malformative nor feto/neonatal toxicity; as a precautionary measure it is preferable to avoid use during pregnancy. Excreted in breast milk - not recommended in breast-feeding women.

Loratadine

Brand names: Clarityn

Loratadine is a non-sedating second-generation oral antihistamine used to relieve the symptoms of allergic rhinitis and chronic urticaria.

Adult dose

Dose: 10 mg (one tablet)
Route: Oral
Frequency: Once daily
Adults: one 10 mg tablet once daily. Paediatric population: children 6 years of age and older with a body weight greater than 30 kg - one tablet (10 mg) once daily; for appropriate dosing in children younger than 6 years or with body weight of 30 kg or less, other formulations are more suitable - verify against a children's formulary. Children under 2 years: safety and efficacy of loratadine tablets have not been established, no data available. Severe liver impairment: a lower initial dose should be used because of reduced clearance - an initial dose of 10 mg every other day is recommended for adults and children weighing more than 30 kg. Elderly: no dosage adjustment required. May be taken without regard to mealtime. Discontinue at least 48 hours before skin tests, since antihistamines may prevent or reduce positive reactions to dermal reactivity index.

Dose adjustments

Renal

No dosage adjustments are required in patients with renal insufficiency.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to the active substance or to any of the excipients

Side effects

  • Somnolence (1.2%)
  • Headache (0.6%)
  • Increased appetite (0.5%)
  • Insomnia (0.1%)
  • Very rare: hypersensitivity reactions (including angioedema and anaphylaxis), dizziness, convulsion, tachycardia, palpitation, nausea, dry mouth, gastritis, abnormal hepatic function, rash, alopecia, fatigue
  • Paediatric (2-12 years): headache (2.7%), nervousness (2.3%), fatigue (1%)

Interactions

  • Potential interaction with all known inhibitors of CYP3A4 or CYP2D6, resulting in elevated loratadine levels and possible increase in adverse events
  • Increased plasma concentrations of loratadine reported with concomitant ketoconazole, erythromycin and cimetidine in controlled trials, but without clinically significant changes (including electrocardiographic)
  • No potentiating effect when administered concomitantly with alcohol, as measured by psychomotor performance studies
  • Interaction studies have only been performed in adults

Clinical monograph

How it works

It is a selective peripheral histamine H1-receptor antagonist that blocks histamine-driven allergic symptoms including itch, sneezing, rhinorrhoea, and urticarial weals.

Prescribing in practice

  • Dose adjustment is advised in significant hepatic impairment, where clearance is reduced; refer to the SPC and use a children's formulary for paediatric dosing.
  • It is generally well tolerated and non-sedating, though occasional drowsiness, headache, and dry mouth can occur.
  • Available over the counter for short-term allergy symptom relief as well as on prescription; review current prescribing references for cautions.

Monitoring

Routine monitoring is not required; assess symptom control and tolerability, with caution in hepatic impairment.

Counselling the patient

  • This usually relieves allergy symptoms without causing drowsiness, but stop and seek advice if it does affect you.
  • It can be taken regularly during periods of allergen exposure such as the pollen season.

Evidence & guidelines

Loratadine and other second-generation antihistamines are recommended first-line for allergic rhinitis and chronic urticaria in NICE and international allergy guidance.

Reference: BSACI; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Calculators
Drugs
Pathways