What to Do About Child Who Is Biting Self?

I was going to say the exact same thing as B - my kids each were given (at some point) their own box of bandaids to have fun with. One decorated my ottoman with her fairy ones.

I'm guessing from your previous post that your 2 year old was getting so much attention for biting and hitting, even if as you say, it was negative attention, that your 4 year old may want some for himself.

We had a little gal that would come over and have a gazillion owies. I said "You get one bandaid per visit" otherwise it was just ridiculous. Her mom made a huge fuss over every bump and scrape, and I didn't. I said here's the sink, and here's the bandaid. She soon lost interest. She just liked attention (what kid doesn't) so I'd just watch their show they'd put on, etc. instead of the attention over being hurt.

Based on this and your last post, it seems to me that you have a 2 year old getting tons of attention (negative, but still attention) for hitting and biting. The 4 year old is the usual target of the toddler, and now he's wanting a pay-off for getting hurt. Maybe you've stopped some of the toddler's actions, but now the 4 y.o. needs and wants some attention and credit for enduring it.

If you put a bandaid on a toy, then a bandaid is for psychological support and not real wounds. So give your 4 y.o. a bandaid for psychological support if he DOESN'T self-harm. No rewards for self-harm. You can set a daily limit of 3 bandaids if you want to discourage waste. If he wants Bandaid #4, he can move an old one (stick it on with tape if you have to).

They're only little for a short period of time. Give them what they need for reassurance.

I don't know.
You're willing to put a bandaid on a broken toy - which doesn't really 'need' one.
So why not just give him a bandaid when he wants one?
It seems a bandaid for nothing is not a huge price to pay so the kid has some attention without having to injure himself to get it.
We had all sorts of fun bandaids - and temporary tattoos too.
At 4 - we didn't worry so much about whether our son needed one or not.
It was no big deal just to put one on him - and he'd get over it soon and forget about it especially when they came off in the bath tub.
Now I don't think you need to go through boxes of them - but one every once in awhile should be ok.

Get him a toy doctor/first aid kit - our son had one - and he'd take my temp with it, gave me a shot, a bandaid and then say I was 'all better' - and it was all pretend - and great fun.
Get him one of these for his birthday or Christmas - he'll love it!
(There are many to choose from - find one that's age appropriate).

https://www.amazon.com/Learning-Resources-Pretend-Play-Do...

I like the other people's answers. I also want to say...my son really had a need to chew on something when he was young. I don't know why. It was a a sensory processing disorder thing for him. He would chew holes in the top of his shirt daily. I ended up getting him a pencil topper he could chew on and a couple other things he could chew on. It did help. Google "kids with sensory issues who need to chew on something". You can order all kinds of chewables. My son had sensory issues big time that he grew out of slowly (for the most part). He still chews his fingernails at age 13.

I remember when my daughter would bite herself. Oh my god, I was freaking because in my last, I self injured. I was so afraid that she must be struggling internally. I would get so frustrated and even cried a few times. I told her she just couldn't do that bc of the risk of infection with open places on her skin. She quit, thankfully! Now she bites her nails and picks her cuticles!
I know it's not exactly the same but just know you're not alone. Also my daughter did this the last time when she was around age 7, so a bit older.