15 year old with Autism only wants to wash on specific days

Hi all,

My brother has autism and he’s more on the low functioning side with limited speech. Getting him to wash has been so difficult because he decides the days he wants to wash. If you say to him “can you go wash now?”, he will repeatedly say “wash Monday, wash monday” increasingly getting louder and more frequent till he starts screaming. It’s so loud and very stressful for me because I’m the one who he torments with this request.

He wants to wash just twice a week but he smells so bad after a few days. We managed to get him to wash every other day but he broke out of that routine. I’ve tried setting up a grid where he gets a sticker for washing on the certain days it says but he lost interest and he wants to do it his way. And there is no forcing him to wash because he will scream and scream and scream till he’s allowed to wash on the day he says he wants to wash. The other day, a few weeks ago, he was screaming for hours because he didn’t want to wash that day.

He knows when he doesn’t wash regularly he will smell, he can smell himself because I catch him sniffing his armpits. But he doesn’t want to go wash when he can smell himself.

I don’t know what to do about this. Can someone offer any advice?