ailment

noun

1. Something which ails one; a disease; sickness.

   “Near-synonym: complaint (contextually synonymous)”

   “He had always been remarkably immune from such little ailments, and had only once in his life been ill, of a vicious pneumonia long ago at school. He hadn't the faintest idea what to with a cold in the head, he just took quinine and continued to blow his nose.”