Excess of food may cause indigestion at the time; and, if often repeated, habitual indigestion called dyspepsia. A less amount of excess or superfluity may bring on an overfulness of rich blood in the system— plethora. Deficiency of food weakens, and so promotes attacks of many disorders; varying according to constitution and exposure.

Indigestible articles may produce common indigestion, with windy pain in the stomach, nausea, etc.; or cholera morbus, which is much more severe; occasionally dangerous.