This study aims to test a new medicine called **barzolvolimab** in adults with two skin conditions: cold induced urticaria (ColdU) and symptomatic dermographism (SD). ColdU is when your skin gets itchy when exposed to cold, and SD is when your skin itches when scratched. The study compares barzolvolimab with a placebo, which looks like medicine but has no active ingredients.

The study includes different phases:

• A Screening Period up to 4 weeks to check if you can join.
• A 24-week treatment period where you get barzolvolimab or placebo.
• A 28-week barzolvolimab treatment period where everyone gets the medicine.
• A 16-week follow-up period to see how you're doing after treatment.

Key Points:

• Participants must be 18 or older with ColdU or SD not controlled by antihistamines.
• You must agree to use effective birth control during and after the study.
• Previous use of barzolvolimab disqualifies you from joining.