Erythema contrast agents

Adverse reactions to iodine contrast agents are rare, especially with the newer non-ionic dimers of low osmolality. Adverse reactions range from mild effects, such as nausea and vomiting, to moderate effects, such as erythema and chest pain. Severe adverse reactions, for example bronchospasm and anaphylactic shock, always need emergency treatment. 

Acute toxic contact dermatitis may be induced by a single application of a toxic material. One local inflammatory skin reaction is characterized by erythema and oedema. This type of reaction occurs following contact with materials such as acids, alkalis, solvents, and cleansers and is rarely associated with topical application of medicinal or cosmetic products. In contrast, irritant contact dermatitis (a superficial non-immuno-logically based reaction) may occur after repeated exposure to many substances, including topical pharmaceutical agents. The reaction is usually localized to the site of exposure and usually diminishes after the stimulus has been removed. Some materials can stimulate an immune response following an initial topical application. Any future exposure may result in an inflammatory immune reaction, an allergic contact dermatitis, or sensitization. 

The systems that cause the most trouble are those in which the drug is dissolved in water, in contrast to ethanolic matrices, which are uncommonly erythema-togenic. The evidence strongly favors hydration as the etiologic agent in most adverse reactions to transder-... 

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