Heat, cold and inflammation.

Although therapeutic heat and cold measures are widely used in rheumatic diseases, their application in joint inflammations is still broadly empirical. Animal experiments concerning the effects of systemic hyperthermia and of local heat and cold applications upon experimentally induced inflammations (dextran edema, formol edema, kaolin edema, carrageenan edema, adjuvant arthritis) show that some inflammations are significantly depressed, i.e. they are effected by a useful therapeutic influence, but that cold and heat can also act as enhancing inflammatory stimulus. Under certain conditions, whole-body hyperthermia has immuno-suppressive effects. Although the exact points of intervention of heat and cold investigations, acute exsudative inflammations seem to be better influenced by cold; on the contrary, chronic torpid and proliferous inflammations are better influenced by heat. Prostaglandin mediated inflammations can be aggravated by cold, because it stimulates the prostaglandin synthesis; acute exsudative inflammatory processes are most often aggravated by heat. These results show that both therapeutic agents should be applied within a well-defined range and with care.