Henry IV Part 2 is consumed with images of illness, decay, and disease. King Henry IV is dying, Falstaff is plagued by illness that accompanies old age (and an excessive lifestyle) and even the lowly commoner, Bullcalf, claims to have a "whoreson cold." At other times, the entire country imagined as a human body wracked with disease, which is an appropriate metaphor for a commonwealth that's plagued by civil rebellion and turmoil. This theme can be traced back to Richard II, when Henry's father, John of Gaunt, accused King Richard II of corrupting England and subjecting the country to "infection" (Richard II, 2.1.3).
In Henry IV Part 2 England is portrayed as a diseased body that must be "purged" of rebellion and disorder in order to be healthy.
In the play, monetary debt is associated with disease – for Falstaff especially, both problems occur when one is overindulgent (from eating, drinking, and spending too much). So, while the play celebrates the raucous and wild behavior it portrays in the infamous tavern scenes, it ultimately suggests that the health of the individual body (and the nation) depends on curbing excessive behavior.