Dermographism can be produced by modest pressure in the skin of normal persons following the application of tetrahydrofurfuryl nicotinate ointment. This local vascular response to pressure lasts up to 96 hours. It does not follow ultraviolet radiation or other chemically induced erythema. Aspirin will prevent the occurrence of dermographism by blocking tetrahydrofurfuryl nicotinate erythema, but aspirin given after induction of the erythema will not prevent dermographism. This dermographism is not prevented by procaine, atropine, cortisone, diphenhydramine, or 48:80. Histamine is not found in dermal perfusates of the dermographic site. Kinin activity is found in such dermal perfusates but not when the site is occluded by a blood pressure cuff, suggesting that this activity comes from the blood. Perfusion of seven patients who had severe clinical dermographism gave similar results.
This study suggests that dermographism, and possibly other forms of physical urticaria, is based on a direct effect of the physical agent on blood vessels and this may be potentiated by chemical agents such as nicotinic acid esters and histamine.