Get key by value in dictionary

I made a function which will look up ages in a Dictionary and show the matching name:

dictionary = {'george' : 16, 'amber' : 19}
search_age = raw_input("Provide age")
for age in dictionary.values():
    if age == search_age:
        name = dictionary[age]
        print name

I know how to compare and find the age I just don’t know how to show the name of the person. Additionally, I am getting a KeyError because of line 5. I know it’s not correct but I can’t figure out how to make it search backwards.