Hi again, @Luna24 , good to see your thread.
I have OCD (germophobia) and am on medication and see a psychologist and psychiatrist regularly. I see both because the psychiatrist is the one who prescribes the meds and the psychologist does the talk therapy. Occasionally you get a psychiatrist who does talk therapy as well, so that way you would only need to see them.
The main therapy for OCD germophobia is ERP Therapy: Exposure Response Prevention Therapy, which is a form of CBT (Cognitive Behavioural Therapy). I have to tell you now, for the OCD sufferer, ERP therapy is terrifying. It involves exposing yourself to germs but not doing any of the washing /cleaning /wiping rituals in response to the exposure. The great fear is of contaminating the rest of your environment, which feels completely overwhelming - how would I possibly ever cope with my whole environment being dirty /germy?
The ERP therapy is of course undertaken in small steps at first. The idea is that the germophobe sees that they are still OK without doing the wiping / washing rituals. To be honest - it hasn't worked very well for me so far. The rituals or compulsions make me feel safe and in control. I think that in some way my germophobia is a desire to control my environment against threats (I have complex childhood trauma). So maybe if you can talk to your son about how he can exert more control in healthier ways, that might help...but please remember, I am only a peer with lived experience, and his psychologist might suggest other things.
I am not a carer or a parent, so I can't help in those ways - I'm hoping others here can. But I can suggest that if you somehow forcibly removed your son's ways of coping - i.e. you didn't permit his washing /cleaning compulsions - it would probably make him worse - well, it would make me worse, anyway! It has to come from within the person. slowly, over time. My cleaning rituals are actually an awful burden, and I wish I didn't have to do them - but the compulsion is stronger.
But I can tell you that I used to put up to 2L of pure disinfectant into my laundry wash each time, and I also used to wash my hands in pure disinfectant sometimes - and I don't do either of those things any more. That came from within me - it wasn't a result of the ERP therapy.
Wishing you all the best as you cope with this.