Bilastine Tablets Uses, Dosage & Side Effects

Sep 03, 2025

Bilastine Tablets 20 mg are a second-generation, non-sedating antihistamine (H1-receptor antagonist) used for the symptomatic relief of allergic rhinitis (seasonal and perennial) and chronic spontaneous urticaria (CSU) in adults and adolescents above 12 years.

What is Bilastine Tablet 20 mg?

Bilastine Tablet 20 mg is a selective, peripherally acting histamine H1-receptor antagonist belonging to the second-generation antihistamine class. It was developed to combine the clinical efficacy of first-generation antihistamines with an optimal safety profile — specifically, without the sedation, anticholinergic effects, or cardiac arrhythmia risks associated with older antihistamines.

Bilastine is chemically classified as a benzimidazole piperidine derivative. It does not cross the blood-brain barrier (BBB) to any clinically significant degree, which explains its non-sedating profile at the standard 20 mg therapeutic dose. The molecule was approved by the European Medicines Agency (EMA) in 2010 and has since been approved in 130+ countries, including India under CDSCO/DCGI regulation.

Mechanism of Action — How Does Bilastine 20 mg Work?

Pharmacological Action	Target	Clinical Result
Selective competitive H1-receptor antagonism	Peripheral H1-histamine receptors	Blocks histamine-mediated allergic response
Inverse agonism at H1 receptors	Constitutively active H1 receptors	Reduces baseline allergic tone
Stabilization of receptor inactive state	H1 receptor conformation	Prolonged antiallergic effect
Minimal CNS penetration	Blood-brain barrier efflux (P-gp substrate)	No sedation at therapeutic dose
No hERG channel blockade	Cardiac potassium channels	No QTc prolongation; cardiac safety
No CYP450 enzyme metabolism	Hepatic CYP system	Minimal drug interactions
No anticholinergic activity	Muscarinic receptors	No dry mouth, urinary retention, blurred vision

Pharmacokinetic Highlights: Bilastine reaches peak plasma concentration (Tmax) in approximately 1.3 hours after oral administration. Its plasma half-life (T½) is around 14.5 hours, supporting reliable once-daily dosing. Bioavailability is approximately 61% under fasting conditions but is significantly reduced (by ~30%) when taken with food or grapefruit juice — hence the mandatory fasting administration instruction. Bilastine is not metabolized by the liver; it is excreted unchanged primarily through urine and feces, making it safe in hepatic impairment.

Indications and Clinical Uses

Bilastine Tablets 20 mg are indicated for the following allergic conditions in adults and adolescents (≥12 years):

1. Seasonal Allergic Rhinitis (SAR — Hay Fever):
SAR is triggered by outdoor aeroallergens such as pollen from trees, grasses, and weeds. Bilastine 20 mg significantly reduces nasal symptoms (sneezing, rhinorrhoea, nasal congestion) and ocular symptoms (itching, redness, tearing) within 1 hour of administration. In the pivotal Phase III BILUS trial, bilastine demonstrated non-inferior efficacy to cetirizine 10 mg and loratadine 10 mg with superior somnolence profile.

2. Perennial Allergic Rhinitis (PAR):
PAR is caused by year-round allergens including house dust mites (HDM), animal dander, cockroach particles, and mold spores. Bilastine 20 mg provides sustained symptom control over 24-hour dosing intervals, making it highly suitable for PAR management requiring long-term antihistamine therapy.

3. Chronic Spontaneous Urticaria (CSU):
CSU is characterized by recurrent wheals and/or angioedema lasting >6 weeks without an identifiable external trigger. According to the EAACI/GA²LEN/EDF/WAO Guidelines (2022), second-generation H1-antihistamines like bilastine are the first-line pharmacological treatment for CSU. Bilastine 20 mg effectively reduces wheal formation, pruritus severity scores (ISS7), and urticaria activity scores (UAS7) in CSU patients.

4. Acute Urticaria:
Bilastine provides rapid onset relief in acute urticaria episodes, including dermographism, cold urticaria, and pressure urticaria, through prompt H1 receptor occupancy following fasting oral administration.

5. Allergic Conjunctivitis:
Bilastine controls ocular allergic symptoms including itching, redness, and lacrimation associated with allergic conjunctivitis, particularly in the context of rhinoconjunctivitis where nasal and ocular symptoms co-exist.

6. Insect Bite Reactions:
Local and systemic histamine-mediated reactions following insect bites (mosquitoes, bees, ants) are effectively managed with bilastine 20 mg for symptomatic relief.

Dosage and Administration

Indication	Dose	Frequency	Route	Duration
Seasonal Allergic Rhinitis	20 mg	Once daily	Oral	During allergen season; typically 2–4 weeks
Perennial Allergic Rhinitis	20 mg	Once daily	Oral	Long-term; reassess every 3–6 months
Chronic Spontaneous Urticaria	20 mg	Once daily	Oral	Minimum 3 months; review per EAACI guidelines
Acute Urticaria	20 mg	Once daily	Oral	Until symptoms resolve (typically 5–10 days)
Allergic Conjunctivitis	20 mg	Once daily	Oral	During symptomatic period

Critical Administration Rule — Empty Stomach Only:
Bilastine must be taken on an empty stomach — at least 1 hour before or 2 hours after food intake. Co-administration with food or grapefruit juice reduces bioavailability by approximately 25–30%, potentially compromising therapeutic efficacy. This is a clinically important instruction that differentiates bilastine from most other antihistamines.

Recommended Timing: Morning administration (30–60 minutes before breakfast) is the most practical approach for most patients, ensuring fasting conditions and full bioavailability.

Special Populations:

Elderly: No dose adjustment required; however, renal function monitoring is advisable in very elderly patients.
Renal impairment: No dose adjustment needed for mild-to-moderate renal impairment; use with caution in severe renal failure.
Hepatic impairment: No dose adjustment required (bilastine is not hepatically metabolized).
Paediatric (<12 years): Not recommended at 20 mg adult tablet formulation; paediatric bilastine formulations (10 mg for 6–11 years) should be used.
Pregnancy/Lactation: Not recommended; use only if clearly necessary under medical supervision.

Side Effects and Safety Profile

Common Side Effects (1–10%):

Headache
Somnolence (at recommended dose: comparable to placebo in clinical trials)
Dizziness
Fatigue
Nausea
Abdominal pain

Uncommon Side Effects (0.1–1%):

Dry mouth
Tachycardia
Insomnia
Anxiety or nervousness
Elevated liver enzymes (transient)
Epistaxis

Rare/Very Rare (<0.1%):

Anaphylaxis or hypersensitivity reactions
Urticaria paradox (hypersensitivity to bilastine itself — extremely rare)
QT interval changes (not clinically established; cardiac safety well documented)

Key Safety Advantages Over First-Generation Antihistamines:
Bilastine 20 mg demonstrated somnolence rates statistically equivalent to placebo (not significantly different) in multiple controlled trials including the BRISA study, clearly differentiating it from sedating first-generation antihistamines like chlorpheniramine and hydroxyzine. Studies using FMRI technology confirmed minimal CNS penetration of bilastine at standard doses, reinforcing its non-sedating classification.

Driving Safety: Bilastine does not impair driving performance at the 20 mg therapeutic dose. Multiple simulator-based studies confirmed no degradation in critical tracking, divided attention, or braking reaction time — unlike first-generation antihistamines and even some second-generation agents at higher doses.

Drug Interactions

Interacting Substance	Mechanism	Clinical Recommendation
Food (any meal)	Reduces bilastine bioavailability by ~25–30%	Always take on empty stomach; 1 hr before or 2 hrs after food
Grapefruit juice	P-glycoprotein inhibition; reduces bioavailability	Avoid grapefruit juice during bilastine therapy
Ketoconazole / Erythromycin	P-gp and OAT3 transporter inhibition	Increases bilastine plasma levels ~2-fold; monitor; avoid if possible
Diltiazem	OAT3 inhibition	Possible bilastine level increase; use cautiously
Alcohol	Additive CNS depression (mild)	Avoid alcohol during antihistamine therapy as a precaution
QT-prolonging drugs	Additive cardiac risk (theoretical)	Not clinically established for bilastine; monitor ECG in high-risk patients
Rifampicin	P-gp induction	Potential reduction in bilastine exposure; clinical significance low

Note: Bilastine is neither a substrate nor an inhibitor of major CYP450 isoenzymes (CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP3A4), making its drug interaction profile significantly cleaner than many antihistamines and most other antiallergic agents.

Contraindications

Known hypersensitivity to bilastine or any tablet excipient
Children below 6 years of age (adult 20 mg formulation)
Severe renal impairment (GFR <30 mL/min) — relative contraindication; use with caution
Co-administration with ketoconazole or erythromycin in patients with pre-existing cardiac conditions or QT risk
Pregnancy and lactation (insufficient safety data; avoid unless benefit outweighs risk)

Bilastine 20 mg vs Other Antihistamines — Comparison Table

Parameter	Bilastine 20 mg	Cetirizine 10 mg	Loratadine 10 mg	Fexofenadine 120 mg	Levocetirizine 5 mg
Generation	2nd generation	2nd generation	2nd generation	2nd generation	2nd generation
Sedation	None (placebo-equivalent)	Mild-moderate	Minimal	Minimal	Mild
Onset of action	~1 hour	~1 hour	1–3 hours	~1–2 hours	~1 hour
Duration	24 hours	24 hours	24 hours	12 hours	24 hours
Food interaction	Yes — must take fasting	Minimal	Minimal	Yes — avoid high fat	Minimal
Hepatic metabolism	None (excreted unchanged)	Minimal	Significant	None	Minimal
QTc risk	None documented	None	None	None	None
CYP interactions	None	None	CYP3A4/2D6 minor	None	None
Driving safety	Confirmed safe	Mild impairment	Safe	Safe	Mild impairment
Dosing	Once daily	Once daily	Once daily	Twice daily	Once daily
CDSCO Schedule	Schedule H	Schedule H	OTC/Rx	Schedule H	Schedule H

Bilastine in Urticaria — Clinical Evidence Summary

The EAACI/GA²LEN/EDF/WAO Urticaria Guidelines (updated 2022) recommend second-generation H1-antihistamines as the unequivocal first-line treatment for CSU, with bilastine specifically referenced as a guideline-endorsed agent. Key clinical data points:

UAS7 Reduction: In the PKIDZ03 pivotal trial, bilastine 20 mg reduced UAS7 scores by 11.5 points vs 5.1 points in placebo (p<0.001), demonstrating statistically and clinically significant urticaria symptom control.
ISS7 (Itch Severity Score): Bilastine produced a 5.8-point reduction in ISS7, vs 2.6 for placebo — a >50% improvement in pruritus severity.
Complete Response Rate: Approximately 35–40% of CSU patients on bilastine 20 mg achieved complete symptom suppression (UAS7 = 0) within 4 weeks.
Long-Term Safety (52 weeks): Open-label extension studies confirmed sustained efficacy and safety of bilastine 20 mg over 52 weeks without tachyphylaxis.

Frequently Asked Questions

Can Bilastine 20 mg be taken at night?

Yes. Bilastine 20 mg can be taken at any time of day, provided the fasting condition is met (1 hour before or 2 hours after a meal). Bedtime administration is acceptable if the patient has fasted for at least 2 hours after dinner. Morning administration before breakfast is generally the most convenient approach.

Does Bilastine 20 mg cause drowsiness or sedation?

No, at the recommended dose of 20 mg, bilastine does not cause clinically significant sedation. Multiple controlled trials using objective CNS performance tests and FMRI imaging confirmed bilastine's somnolence rate is statistically indistinguishable from placebo. This makes it particularly suitable for patients who need to drive, operate machinery, or perform cognitively demanding tasks.

Why must Bilastine be taken on an empty stomach?

Food reduces bilastine's oral bioavailability by approximately 25–30%. Grapefruit juice similarly impairs absorption. To ensure full therapeutic plasma concentrations are achieved, bilastine must be taken at least 1 hour before or 2 hours after eating. This is a pharmacokinetically important instruction unique to bilastine among common antihistamines.

How is Bilastine 20 mg different from Cetirizine and Levocetirizine?

Bilastine offers a superior sedation profile compared to cetirizine and levocetirizine, with sedation rates equivalent to placebo versus mild CNS effects reported with both cetirizine and levocetirizine at standard doses. Bilastine also has no hepatic metabolism and no CYP450 interactions, offering a cleaner pharmacological profile for polypharmacy patients. Driving and cognitive performance are unaffected by bilastine.

Is Bilastine safe for long-term use in Chronic Urticaria?

Yes. Bilastine 20 mg has demonstrated sustained efficacy and an excellent safety profile over 52 weeks of continuous use in chronic spontaneous urticaria trials. No clinically significant adverse effects accumulated with long-term use, and no cardiac, hepatic, or renal safety signals emerged in extended studies. Long-term use should nonetheless be under periodic physician review.

Is bilastine a steroid?

It is a non-sedating, second-generation antihistamine used to treat allergic conditions

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