My son had a flu shot on saturday at clicks. today the spot is red and hard. his arm is very sore. is this normal, if not, what should i do?

Some local rxn ok: It is not uncommon to have some redness at the site of injection for many vaccines, but, in general, this is not very common with the flu vaccine unless there is a mild allergy to one of the ingredients. If the area of redness is about 1 inch in diameter or less, try cold compresses for a day and oral Motorin. If larger than 1 inch now or getting larger, seek medical care for possible infection.