there is a nail polish that contains ingredients to help make your nails grow. it's called, sally Hansen maxim growth plus, it is a base color of white and you can put whatever color you want over it. but you must stop biting your nails also. good luck!
well a better way would be to consume more protein. i doubt there is stuff out there to actually physically put on your nails to make them grow but eating proteins like eggs and fish are good for your hair and nails. itll make it grow faster and healthier :)
People bite their nails because of stress. I used to bight my nails but to stop me from doing that one day I got my nails done at a salon. It kept me from biting my nails because I didn't want to ruin my nail polish. It might not work for you but it definitely worked for me. If you are trying to grow your nails out, I seriously recommend Sally Hansen's Miracle Growth. It works really well.
Take vitamin E it will make you nails grow stronger n you hair too. but of corse you have to file your nails as they grow so they dont chip or split and comb your hair with a comb not a brush as a brush will frizz your hair.