Methods and compositions for treating acute suicidality by administration of buprenorphine are disclosed herein. An exemplary method is effected by administering to a subject determined as having acute suicidality a first therapeutically effective amount of buprenorphine, or a pharmaceutically acceptable salt thereof, whereby the administration is ceased once the subject is no longer determined as having acute suicidality. The first therapeutically effective amount is less than 0.2 mg per day. A higher therapeutically effective amount may optionally be administered if the subject is determined as not fully responsive to the first therapeutically effective amount. Unit dosage forms of buprenorphine, comprising less than 0.2 mg (e.g., 0.1 mg) buprenorphine are also disclosed.
