There is no single recipe to make 'Sickness' in Little Alchemy, but there are some combinations that you can use to create items that are related to sickness, such as Medicine, Illness, and Disease.
To make Medicine in Little Alchemy, combine Life + Bottled Water or Water + Clay.
To make Illness in Little Alchemy, combine either Medicine + Mud or Medicine + Air.
To make Disease in Little Alchemy, combine either Swamps + Wind or Swamps + Air.
