I burned my hand pretty bad?

Earlier when i was about to take a shower i moved some stuff off of the sink so i can put my clothes right there and when i grabbed my moms hair straightener thing i didnt know it was still hot and i burned my whole hand. You can se where the irons burned me because its all red and imprinted on my hand. I put my hands in cold water for 20 minutes but my fingers still feel kind of numb and hurts. Do i need medical attention?