Background: Of young people with first episode psychosis (FEP), over half report exposure to childhood trauma and consequent co-morbid post-traumatic stress disorder (PTSD) or symptoms. Currently no evidence-based interventions exist for PTSD in FEP. Clinicians report concerns that trauma-focused interventions with young people with FEP could result in distress and symptom exacerbation. Scant research suggests that talking about trauma in therapy can be distressing for some people. Aims: To explore young people's reactions to a trauma-focused treatment for PTSD in FEP. Method: Semi-structured interviews were conducted with eight participants (age 18–27 years) with co-morbid PTSD and FEP, after completing a trauma-focused intervention. Transcripts were analysed using an interpretative phenomenological approach. Participants’ baseline and end-of-treatment PTSD and psychotic symptoms were assessed. Results: Three themes related to participants’ reactions were identified from the analysis: (1) distress in session; (2) feeling relieved in and out of session; and (3) symptom exacerbation out of session. All but one participant reported experiencing increased distress in session. Four participants described PTSD, psychotic symptoms and/or suicidal ideation worsening in immediate reaction to talking about trauma in therapy sessions. 86% of participants showed improvement in their PTSD and psychotic symptoms at end of treatment. All participants described the intervention as beneficial and worthwhile. Conclusions: Results suggest that feelings of distress are to be expected from individuals with PTSD and FEP during trauma-focused treatment. Psychotic and PTSD symptom exacerbation can occur in PTSD treatment in FEP. Clinicians should be aware of, plan for, and clearly inform their clients of treatment risks.