My two year old toddler on wednesday was bitten on her hand at the top of the wrist by what i assumed a mosquito. she scratched it and since yesterday the hand is very swollen and has red blotches.

Anti itch may help.: It is important to prevent scratching by probably using cortisone cream or anti itch cream to reduce chances of scratching that may increase chances of ulcer and infection. You may also try and get mosquito repellant cream to use when outside and wear long sleeves and long pants to reduce area of possible mosquito bites when outside.

See a doctor: I agree with Dr. Kratzberg, but if that treatment for the itching isn't helping, the local topical treatment for a local reaction may not be enough, so an oral antihistamine may be needed. If the redness and swelling are not improving or are worsening, your toddler's hand may be infected and she may need to see a doctor for further treatment.