Advice Needed Habit of biting Finger Nails.

There's a special substance you can get which you put on your fingernails and I believe it tastes horrible so it stops you from biting them.

I've never used it however my sister used to have a big problem with biting hers and therefore my parents got it for her when we were younger.

I can't find the link for it though i assume you can find it at Boots stores etc (UK).