Would Botox injections for the hands be ok for a 14 yr old?

Botox is effective in treating excessive sweating of the palms and usually lasts anywhere from 4 - 6 months. I recommend seeing a board certified plastic surgeon for an evaluation. 

Botox is highly effective
and safe treatment for excessive sweating of the
palms (hyperhidrosis). Botox will last 4-6 months and is an excellent treatment to manage
this condition. This should be done in the hands of a Board Certified Plastic Surgeon or Dermatologist
trained in this area.

Your daughter might get some great benefit from Botox for sweating. She will need to be mature enough to allow several small needle pricks in her hands. Topical numbing can be applied first to help minimize the discomfort. I would suggest taking your daughter to a board certified plastic surgeon or dermatologist and discussing all the options.