Sources of Inhibited Healing include Malaise Damage, Disease/Illness, Toxins/Poisons (natural or by Abolition Reagents), Infection and mystical effects.
The affect of a general sickness typically rob the character of their energy and ability to gain superior benefits of their skill and powers.
A character with the Ill condition suffers a loss of 5′ of Movement unless they possess a Constitution of 14, have their Maximum HP reduced by 3 (preventing the Hale condition) and have all instances of Advantage negated on any check.