Autistic people experience a higher prevalence of self-harming behaviours than do the general population. Self-harm remains a stigmatised topic, and until recently, self-harming behaviours in autism were considered to be limited to self-injurious behaviours experienced by intellectually impaired autistic children and not to be experienced by cognitively able autistic adults. Because of the belief held by many professionals that many mental health-related problems are inherently part of autism and immune to treatment or help, many autistic people are left unable to access the help and support that they desperately need. This study adopts an online qualitative methodology to explore this under-researched phenomenon, thematically analysing online forum posts from autistic adults to determine what forms of self-harm are described, what precipitates the self-harm and how forum users support each other. The findings reveal that self-harming behaviours are nuanced and complex, highlighting the connections between sensory overload, meltdowns, stimming and impulsive repetitive blunt trauma seen as autistic self-injurious behaviours. When seeking help, barriers include navigating misdiagnoses of other mental illnesses and being misunderstood or disbelieved by professionals. Online forum users offer help in the form of emotional empathy, as well as practical solutions, providing an example of valuable peer support. Lay abstract There is a higher prevalence of self-harming behaviours within the autistic community than is experienced by the general population, in addition to co-occurring mental health conditions such as anxiety and depression. To date, research has focused on quantifying and categorising the numbers of autistic people self-harming, what types of harming they are engaging in and what functions the harming performs. Autism research has historically focused on the opinions and experiences of parents, carers and clinicians, with a belief that autistic people are unable to present their own experiences and thoughts accurately. This study adopted a qualitative method to develop themes arising from online forum discussions, using the words of autistic adults talking about how they experience and understand their self-harming behaviours. The analysis discovered that self-harming behaviours are used by autistic people as a way of coping with anxiety and depression and to relieve the build up of stress and sensory or mental overload that can otherwise lead to a meltdown. Repetitive behaviours such as stimming are also used to relieve the buildup of sensory over-stimulation and anxiety, but both stimming and meltdowns can also be self-harming behaviours if they cause tissue damage, and are believed to be childhood presentations which are stigmatised if expressed by an autistic adult. Many autistic adults find it hard to get help with self-harming behaviours because they are not taken seriously by professionals, as it is seen as part of autism and cannot be helped, or the professionals do not have enough knowledge of autism
