Non-sedating Antihistamine (H1 Antagonist — Second-generation) 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, Benadryl Once A Day

Loratadine is a non-sedating second-generation oral antihistamine used for allergic rhinitis and chronic urticaria.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 10 mg (one tablet)

Route: Oral

Frequency: Once daily

General medicine / non-sedating antihistamine use. 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 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: an initial dose of 10 mg every other day is recommended for adults and children weighing more than 30 kg because of reduced clearance. 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. Indications covered by the safety data include allergic rhinitis and chronic idiopathic urticaria. Contains lactose monohydrate - not suitable for patients with rare hereditary problems of galactose intolerance, total lactase deficiency or glucose-galactose malabsorption.

Dose adjustments

Renal

No dosage adjustments are required in patients with renal insufficiency.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. 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-mediated allergic responses while crossing the blood-brain barrier poorly, limiting sedation.

Prescribing in practice

It is generally well tolerated and only mildly sedating, but advise caution as a minority of patients still experience drowsiness affecting driving or skilled tasks.
Dose adjustment may be needed in significant hepatic impairment.
Antihistamines are usually withheld before allergy skin testing as they can suppress the response.

Monitoring

No routine monitoring is required for this generally well-tolerated antihistamine.

Counselling the patient

It is usually taken once daily and is less likely to cause drowsiness than older antihistamines.
It can be taken with or without food.
Tell your clinician if symptoms persist despite treatment.

Evidence & guidelines

Non-sedating antihistamines such as loratadine are recommended first-line in NICE guidance for allergic rhinitis and chronic urticaria.

Reference: NICE CG134 (Allergic Rhinitis); 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).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways