• Written informed consent obtained from potential participants capable of providing informed consent, after the nature of the trial has been fully explained and before performing any trial related assessments

• Males and females, ≥18 years old

• Diagnosis of ColdU or SD despite the use of H1-antihistamines as defined by all of the following:

‣ Diagnosis of ColdU or SD for ≥ 3 months, symptoms must comprise both wheal and itch or painful sensation

⁃ Presence of itch and hives for ≥ 6 consecutive weeks at any time prior to Screening despite current use of H1-antihistamines (as reported by the participant)

⁃ ColdU participants must have a positive cold stimulation tests above 4ºC using TempTest® (wheal and itch or painful sensation) on site during Screening to be eligible

⁃ SD participants must have a positive FricTests® with ≥ 3 pins (wheal and itch) on site during Screening to be eligible

• Use of H1-antihistamines on stable dose up to four-fold of the approved dose for at least 4 weeks prior to the Screening visit and not expected to change during first 12 weeks of the trial.

• Participants with chronic spontaneous urticaria (CSU) are eligible if they present with symptoms consistent with ColdU or SD and ColdU or SD is the dominant type of chronic urticaria.

• Blood counts at Screening with:

‣ Hemoglobin: ≥ 11 g/dl

⁃ Platelets: ≥ 100,000/mm3

⁃ Leucocytes: ≥ 3,000/mm3

⁃ Neutrophils: ≥ 2,000/mm3

• Willing and able to participate and adhere to the trial visits schedule.