After an acute disease with fever--as scarlet fever, measles, typhoid fever, etc.— convalescence is accompanied by more or less debility. But when everything goes well, appetite is then strong, and the losses of the system are made up by the appropriation of food. A person who was healthy before such an attack will commonly need no help from medicines to " build up " again.

Running down in strength, however, with or without acute disease, and often without any fixed disorder of any great organ, is not uncommon, from various causes. Too severe, monotonous, and long-continued labor, out of proportion to one's strength; worry, particularly when it prevents refreshing sleep; living in a close air, without change and exercise; these are some of the conditions in which people are apt to get down " below par " in strength.

Poverty of blood (antenna) is generally present in such cases. So is loss of appetite and digestive power; and nervous depression. These are the three elements of ordinary continued debility.