My brother has athlete's foot. is that something important?

Depends: So called athlete's foot is fungal infection of the skin and by itself is not dangerous. It causes itching, flaking of skin and infection of the nails causes deformity of nails. It is important in diabetics and those with peripheral vascular disease to have it treated to prevent additional infections and other complications like ulcers and even gangrene.

No: Tolnaftate is still the best remedy, and it's over-the-counter. He can wear sandals in the group shower so as not to pass it to others, and keep the spaces between his toes dry after he bathes.