Antihistamine (H1, second-generation, non-sedating) Pregnancy: There are no or limited data in pregnant women; as a precautionary measure it is preferable to avoid bilastine during pregnancy. Excretion in human milk has not been studied (animal data show excretion in milk) - decide whether to continue/discontinue breast-feeding or bilastine weighing the benefits of each.

Bilastine

Brand names: Ilaxten

Bilastine is a non-sedating second-generation H1 antihistamine used for allergic rhinoconjunctivitis and 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: 20 mg (1 tablet) once daily

Route: Oral

Frequency: Once daily, taken one hour before or two hours after food or fruit juice

Adults and adolescents (12 years of age and over): 20 mg bilastine once daily for the relief of symptoms of allergic rhinoconjunctivitis (seasonal and perennial) and urticaria. Swallow the tablet with water; take the daily dose in one single intake. Duration: for allergic rhinoconjunctivitis limit treatment to the period of allergen exposure - seasonal allergic rhinitis treatment may be stopped once symptoms resolve and restarted on reappearance; in perennial allergic rhinitis continued treatment may be proposed during allergen exposure periods. For urticaria the duration depends on the type, duration and course of the complaints. Elderly and hepatic impairment: no dosage adjustment required. Paediatric population (non-weight-based, from the same SPC): children 6 to 11 years with a body weight of at least 20 kg should use bilastine 10 mg orodispersible tablets or 2.5 mg/mL oral solution; children under 6 years or under 20 kg - no posology recommendation can be made and bilastine should not be used. Product: Bilastine 20 mg Tablets.

Dose adjustments

Renal

No dosage adjustment is necessary in adults with renal impairment; however, avoid coadministration with P-glycoprotein inhibitors in patients with moderate or severe renal impairment

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — 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

Headache (common, 4.01%)
Somnolence (common, 3.06%)
Dizziness (uncommon, 0.83%)
Fatigue (reported among the most common ADRs)
Electrocardiogram QT prolonged (uncommon, 0.53%)
Upper abdominal pain, nausea, diarrhoea, dry mouth (uncommon)

Interactions

Food significantly reduces the oral bioavailability of bilastine by 30% - take 1 hour before or 2 hours after food
Grapefruit juice (and possibly other fruit juices) decreased bilastine bioavailability by 30% via OATP1A2 inhibition
Ketoconazole 400 mg once daily or erythromycin 500 mg three times daily increased bilastine AUC 2-fold and Cmax 2-3 fold (P-gp interaction)
P-glycoprotein inhibitors (e.g. ketoconazole, erythromycin, ciclosporin, ritonavir, diltiazem) - avoid coadministration in patients with moderate or severe renal impairment (increased bilastine levels and risk of adverse effects)
OATP1A2 substrates or inhibitors such as ritonavir or rifampicin may decrease bilastine plasma concentrations
Other medicinal products associated with QT/QTc prolongation - caution (QT prolongation has been reported with bilastine)

Clinical monograph

How it works

It is a selective peripheral histamine H1 receptor antagonist that suppresses histamine-mediated allergic symptoms.

Prescribing in practice

It should be taken on an empty stomach because food and fruit juices substantially reduce its absorption.
It undergoes minimal hepatic metabolism and is largely excreted unchanged, which limits relevant drug interactions.
Concurrent use with certain transporter-inhibiting drugs may increase its plasma levels.

Monitoring

Routine monitoring is not required; review symptom control clinically.

Counselling the patient

Take at least one hour before or two hours after food or fruit juice.
Report any unexpected drowsiness.
Use regularly during allergy season for best symptom control.

Evidence & guidelines

Second-generation antihistamines such as bilastine are recommended first-line for allergic rhinitis and chronic urticaria in current guidance.

Reference: SmPC Ilaxten; BSACI Rhinitis Guideline 2017; EAACI/GA²LEN Urticaria Guideline 2022; Confirm identity and dosing against the manufacturer SPC (eMC) and NICE. 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

Drugs

Desloratadine · Antihistamine (H1, second-generation, non-sedating)

Pathways