• Adults ≥ 18 years of age at the time of signing the informed consent

• CSU duration for ≥ 6 months prior to screening (defined as the onset of CSU determined by the Investigator based on all available supporting documentation)

• Diagnosis of CSU inadequately controlled by sgH1-AH at the time of randomization, defined as:

• The presence of itch and hives for ≥ 6 consecutive weeks prior to screening despite the use of sgH1-AH during the 7 days prior to randomization (Day 1):

• UAS7 score (range, 0-42) ≥ 16, and

• ISS7 score (range, 0-21) ≥ 6, and

• HSS7 score (range, 0-21) ≥ 6

• Documentation of hives within 3 months before randomization (either at screening and/or at randomization); or documented in the participants medical history

• Willing and able to complete an Urticaria Patient Daily Diary (UPDD) for the duration of the study and adhere to the study protocol

• Participants must not have had more than one missing UPDD entry (either morning or evening) in the 7 days prior to randomization (Day 1)