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Inclusion Criteria:

* Male or female participant must be ≥18 years old at the time of signing the informed consent.
* Participants are diagnosed with CSU for ≥6 months before screening.
* Participants suffer from itching and hives for at least 6 consecutive weeks at any time before screening.
* UAS7 (range 0\~42) ≥16, ISS7 (range 0\~21) ≥8 during 7 days before randomization.
* Participants treated with stable dose of second-generation H1 antihistamines (up to 4x approved dose) for at least 6 consecutive weeks before randomization, switching medications, or changing drug dosage or frequency is not allowed within 3 weeks before randomization.
* Participants have ≥6 days record of UAS7 before randomization.

Exclusion Criteria:

* Participants who suffer from inducible urticaria with definite inducements, including urticaria factitia (dermatographism), cold contact, heat contact, solar, pressure, delayed pressure, aquagenic, cholinergic or contact urticaria, etc.
* Participants who suffer from any other skin diseases with chronic itching, such as atopic dermatitis, bullous pemphigoid, dermatitis herpetiformis, senile pruritus or psoriasis, etc.
* Participants who suffer from other diseases with symptoms of urticaria or angioedema, including but not limited to urticaria vasculitis, urticaria pigmentosa, erythema multiforme, mastocytosis, hereditary urticaria or acquired/drug-induced urticaria.
* Participants who are contraindicated or hypersensitive to antihistamines or any of its component (such as fexofenadine, loratadine, desloratadine, cetirizine, levocetirizine, rupatadine, bilastine).
* History of anaphylactic shock.

• Beijing, China