Inclusion Criteria:  - Adolescents aged 12 to 18 years; Exposed to a single traumatic event or to events circumscribed in time, including sexual abuse in the absence of reminders in the environment; Fluent in French; Positive diagnosis of PTSD with the SCID-5; Disorders evolving for at least three months; Heart rate ≥ 55 bpm; Systolic blood pressure ≥ 100 mmHg; Written parental or legal guardian consent; Written agreement by the adolescent; Adolescents affiliated, via their parents, to the French social security body.  Exclusion Criteria:  - Medical condition contraindicating administration of propranolol (COPD, asthma, cardio-vascular insufficiency, heart failure as second- and third-degree atrioventricular blocks, Prinzmetal angor, pheochromocytoma, Raynaud disease, history of an anaphylactic reaction, sinus node disease, hypoglycemia, AV blocks) Known chronic renal or hepatic insufficiency Schizophrenia; Mental retardation; Autism spectrum disorder; Acute severe suicidal ideation Traumatic brain injury (loss of consciousness > 10 minutes); Currently treated for substance or alcohol dependence; Currently treated for Attention Deficit Hyperactivity Disorder; Currently treated with a drug that can interfere with propranolol and that can represent a danger according to medical advice if it's suspended more than 24 hours. Currently treated with a bradycardic drug; Concurrent psychotropic medication with the exception of cyamemazine (suspended 48 hours before session) Concurrent trauma-focused psychotherapy in progress or stopped less than 1 month ago; Pregnancy or breast feeding. Current use of "recreative" toxic drugs Concurrent participation to another interventional study