My son continuously itches his hair and head especially when he sweats. he has no lice and no dandruff . what might be causing it ?

Possible Fungus: Of the 5 common causes for itchy scalp (Seborrhea (dandruf), Psoriasis (inflammation), Fungus (ring worm), Head Lice, and Allergy), Fungal seems most likely. Try using an Anti-fungal shampoo or scalp cream. The pharmacist should be able to point out one that is safe for your son's age. Follow the directions on the shampoo. If this does not help, you should have his scalp examined. Hope this helps!