Sickness adjectives are listed in this post. Each word below can often be found in front of the noun sickness in the same sentence. This reference page can help answer the question what are some adjectives commonly used for describing SICKNESS.
actual, altitude, awful, bad, bodily, chronic, common, considerable, constant, contagious, continual, continued, dangerous
deadly, deathly, distressing, dreadful, epidemic, evil, extreme, fatal, fearful, first, frequent, general, great
green, grievous, heavy, human, incurable, last, late, less, lingering, little, long, mental, moral
more, mortal, much, mysterious, natural, new, other, own, painful, physical, present, previous, prolonged
protracted, real, recent, same, serious, serum, severe, sharp, short, sore, spiritual, strange, such
sudden, sweating, tedious, terrible, unusual, very, violent
Hope this word list had the adjective used with sickness you were looking for. Additional describing words / adjectives that describe / adjectives of various nouns can be found in the other pages on this website.