Hi! I completely understand your concern because this could be a safety issue. Have you tried occupational therapy to help your son for his sensory issue? It could either be sensory or behavioral and for my son it was both. You could ask you pediatrician for OT and ABA therapy since he has a diagnosis for autism, insurance should cover these therapies. My son use to do the same thing. One thing you can do is when he bangs his head you can ask him if he needs something example are you tired? Hungry? If none of it is the cause, remove him from the situation and give him a more appropriate toy or activity. Also, tell him it’s not safe to bang his head. Set a time for 30 minutes and check on him so often if he repeats the head banging it takes practice and constant reminder and hopefully the behavior faded out. Hope this helps

Yes this is a common issue. It generally means that their sense of feeling is hyposensitive. In Autism, sensory issues are common.. the senses can be heightened or lowered to any degree. Hearing, sight, taste, smell and the sense of feeling can be overwhelming or underwhelming. Sometimes certain senses are at a typical level.
A lot of times head butting can be a form of communication or your child’s way of simply trying to feel something. My son pinches* himself a lot and doesn’t really feel pain like the rest of us!
Hope this helps and feel free to ask any other questions <3

Thank you for this xxx