The study consists of a Screening Phase during which eligibility is confirmed, a Treatment Phase in which participants will be randomized and receive double blinded study drug to treat 2 qualifying HAE attacks (i.e., 2 Treatment Periods within the Treatment Phase), and an End-of-Study Follow-up Phase after the second attack treated with study drug. In addition, for adolescent participants (age ≥12 to \<18 years), PK samples are collected after administration of deucrictibant at Day 1 in a non-attack state.
