“Rituals or rivalry?” The phenomenology and treatment of sibling specific obsessions in paediatric obsessive-compulsive disorder

•Young people with OCD can present with specific fears relating to a sibling.•Sibling obsessions can lead to high levels of family conflict and dysfunction.•Sibling obsessions to not reflect an underlying rivalry or resentment.•Careful assessment is critical in identifying sibling obsessions.•Sibling specific obsessions can respond to standard treatment for OCD.

Obsessive-compulsive disorder (OCD) is highly heterogeneous, and can be difficult to assess and diagnose particularly when unusual symptoms are present. This case study (n=9) describes an under-reported presentation of OCD in youth, whereby the patient experiences an obsessional fear of a sibling. Clinical characteristics of this presentation are discussed and comparisons with sibling rivalry disorder are examined. Seven of the participants engaged in a standard treatment protocol for OCD (comprising cognitive-behaviour therapy with or without an SSRI medication); five achieved remission. This presentation of sibling obsessions should be recognised as OCD, and be treated with evidence-based interventions for OCD.