The first symptom of ironshank is a log message stating, "Your legs ache at the joints". Some days after the first time this message is displayed, the player is shown another message stating, "You have contracted Ironshank! You feel the cartilage stretch as your leg bones grind together at the joints." As soon as this message is displayed, the player's move speed drops by roughly 8.
Several days later, the same message is displayed again in red, as move speed is reduced by 10.
This message will be displayed again at semi random intervals (a little less frequent than once per day), with move speed going down each time.
Drinking certain substances, like honey and slime on a one dram per substance per day schedule seems to stop the progression of ironshank, but not reverse its effects. To cure ironshank, consult the Corpus Choliys; it will tell you which other substance to add to gel at a 1-1 ratio to create the cure. Drink one dram a day until you receive the message "Your ironshank is cured!" To get gel add one Desalination Pellet to a container of slime, to receive an equal volume of gel.