Illness adjectives are listed in this post. Each word below can often be found in front of the noun illness in the same sentence. This reference page can help answer the question what are some adjectives commonly used for describing ILLNESS.
actual, acute, advanced, affective, alarming, alleged, associated, bad, bipolar, bodily, borne, brief, catastrophic, certain, chronic, clinical, common, comorbid, complex, concurrent, constant, contagious, continued, critical, cure, current, dangerous
deadly, debilitating, defining, degenerative, dementing, depressive, desperate, devastating, diarrheal, difficult, distressing, dreadful, early, emotional, environmental, even, extended, extreme, fatal, febrile, feigned, final, first, flulike, foodborne, former, frequent
future, gastrointestinal, general, genetic, grave, great, grievous, hopeless, human, incapacitating, incurable, induced, infectious, initial, intercurrent, intestinal, last, late, lengthy, lifelong, lifethreatening, like, lingering, little, long, major, maternal
medical, mental, mild, minor, more, mortal, much, mysterious, nervous, neurologic, neurological, new, occupational, old, only, ordinary, organic, original, other, own, painful, particular, past, personal, physical, possible, present
pretended, preventable, previous, primary, progressive, prolonged, protracted, psychiatric, psychological, psychosomatic, psychotic, rare, real, recent, recurrent, related, respiratory, sad, same, second, serious, severe, sharp, short, significant, similar, slight
social, specific, spiritual, strange, subsequent, such, sudden, systemic, tedious, temporary, term, terminal, terrible, threatening, treatable, underlying, undiagnosed, unexpected, unexplained, unfortunate, unknown, violent, viral, whole, widespread
Hope this word list had the adjective used with illness you were looking for. Additional describing words / adjectives that describe / adjectives of various nouns can be found in the other pages on this website.