We present a case of a young adult with both Cornelia de Lange syndrome and Ehlers-Danlos syndrome. The patient showed non-verbal autism, intellectual disability and severe/intractable self-harming behaviours that led to a life-threatening complication (ie, septicaemia). A significant reduction in the self-harming behaviours was attained in a multidisciplinary neurobehavioural inpatient unit after addressing all causes of somatic pains, managing pain using level II and III analgesics, stabilising the patient's mood, limiting the iatrogenic effects of multiple prescriptions and offering a specific psychoeducational approach.