Best known historically for producing the antibiotic penicillin, P. chrysogenum often appears as blue-green, velvety colonies. Despite its medical significance, indoors it is a common spoilage mould on damp walls, cellulose materials, and various foods. Inhaling its spores can cause respiratory irritation, especially in people with mould allergies. Controlling indoor humidity and swiftly addressing water damage can reduce the likelihood of infestation.
