Mens Silk Underwear Are There Mens Underwear Not Made Of Cotton?

Are there mens underwear not made of cotton? - mens silk underwear

My friend has just found out they are allergic to cotton. I can not wear boxers or briefs. Silk does not like. Is there another type of cotton fabrics not? What would be a good choice? Where can I buy? At the moment he is wearing silk, but I must do something soon! He will not! HELP!