In an adult with perennial allergic rhinitis or chronic spontaneous urticaria, which is the preferred first‑line oral antihistamine: bilastine 20 mg once daily or desloratadine 5 mg once daily?

Bilastine vs Desloratadine for Perennial Allergic Rhinitis and Chronic Spontaneous Urticaria

Both bilastine 20 mg and desloratadine 5 mg are equally effective for controlling symptoms of perennial allergic rhinitis and chronic urticaria, but bilastine is the preferred choice when absolute avoidance of sedation is critical—such as in patients who drive, operate machinery, or have high fall risk—because it demonstrates a superior safety profile with significantly less somnolence and fatigue than other second-generation antihistamines. 1, 2

Evidence for Equivalent Efficacy

• Head-to-head randomized controlled trials demonstrate that bilastine 20 mg once daily and desloratadine 5 mg once daily produce statistically equivalent reductions in total symptom scores for seasonal allergic rhinitis, with no significant difference between the two agents in controlling nasal symptoms (rhinorrhea, sneezing, itching, obstruction) or non-nasal symptoms (ocular itching, tearing, redness). 1

• Both agents significantly outperform placebo in reducing area-under-the-curve total symptom scores (bilastine 98.4 vs desloratadine 100.5 vs placebo 118.4; P < 0.001 for both active treatments vs placebo), and both improve rhinoconjunctivitis quality of life scores to a similar degree. 1

• Desloratadine 5 mg once daily rapidly reduces symptoms of perennial allergic rhinitis with improvement observed after the first dose and sustained efficacy throughout 4 weeks of treatment, reducing morning-evening instantaneous total symptom scores (P = 0.005) and reflective total symptom scores (P = 0.007). 3

Critical Safety Advantage of Bilastine

• Bilastine demonstrates a significantly better adverse event profile than cetirizine 10 mg, with only 1.8% of patients experiencing somnolence compared to 7.5% with cetirizine (P < 0.001) and only 0.4% experiencing fatigue compared to 4.8% with cetirizine (P = 0.02), while maintaining comparable efficacy. 2

• The incidence of treatment-emergent adverse events with bilastine 20 mg (20.6%) is virtually identical to placebo (18.8%) and desloratadine (19.8%), confirming its excellent tolerability. 1

• Bilastine lacks anticholinergic effects, does not impair psychomotor performance or actual driving ability, and appears entirely free from cardiovascular effects, making it particularly suitable for patients requiring unimpaired cognitive and motor function. 4

Clinical Decision Algorithm

Choose Bilastine 20 mg Once Daily When:

• The patient operates vehicles, heavy machinery, or performs safety-critical tasks where even minimal sedation risk is unacceptable. 2

• The patient is elderly or at high risk for falls, because older adults are more sensitive to psychomotor impairment from antihistamines and bilastine's lower sedation potential is clinically critical in reducing accident risk. 5

• The patient has previously experienced sedation or performance impairment with other second-generation antihistamines (including desloratadine at higher doses or cetirizine). 2

Choose Desloratadine 5 mg Once Daily When:

• Cost is a primary concern, as desloratadine is typically less expensive and widely available as a generic formulation. 5

• The patient has simple perennial allergic rhinitis without significant nasal congestion and does not have occupational or safety concerns requiring absolute avoidance of sedation. 5, 3

• The patient has coexisting asthma, because desloratadine offers superior decongestant activity and anti-inflammatory effects that may provide additional benefit. 5

Important Limitations of Both Agents

• Neither bilastine nor desloratadine provides substantial relief of nasal congestion; both effectively reduce rhinorrhea, sneezing, and itching but have limited objective effect on nasal obstruction. 5, 1

• When nasal congestion is a prominent symptom, add an intranasal corticosteroid to achieve comprehensive symptom control, as intranasal corticosteroids remain more effective than oral antihistamines for controlling the full spectrum of allergic rhinitis symptoms. 6, 5

Renal Impairment Considerations

• Both agents should be used with caution in severe renal impairment (creatinine clearance <10 mL/min), but neither requires dose adjustment in mild-to-moderate renal impairment, unlike cetirizine which requires 50% dose reduction in moderate renal impairment. 5

Common Pitfall to Avoid

• Do not assume all second-generation antihistamines have identical sedation profiles; there are critical differences that impact patient function, and bilastine's demonstrated lower sedation rate in head-to-head trials makes it the safer choice when performance impairment must be absolutely avoided. 5, 2

• Performance impairment can occur even when patients don't subjectively feel drowsy, so proactively selecting the least sedating agent (bilastine) is preferable to waiting for a patient to report drowsiness with desloratadine. 5