Adverse effects and lack of efficacy in a significant number of patients limit pharmaceutical interventions in youth psychiatry. This is exemplified by the fact that no medication is currently approved for the treatment of non-OCD anxiety disorders or major depressive disorder in young people younger than 18 years of age in Australia. Here, emerging biological therapies for youth with mental health problems are discussed. There is an urgent need for more research into biological interventions with acceptable risk–benefit balances. Omega-3 fatty acids, cannabidiol and N-acetylcysteine are currently being evaluated. If initial findings are confirmed, they may offer alternatives with more benign side-effect profiles than existing treatments.