Allergic reactions cutaneous manifestations

Cholestatic jaundice is observed infrequently, usually during the first few weeks of treatment. This is thought to be a hypersensitivity reaction and is usually mild and self-limited. Cutaneous allergic reactions are occasionally reported. Both types of problems normally disappear upon changing to an antipsychotic from a different chemical class. Photosensitivity usually manifests as an acute hypersensitivity reaction to sun with sunburn or rash, but the condition is generally mild and does not require dosage adjustment. 

In Ippen s (1978) case of contact eczema, the epicutaneous test, with isoniazid as substance or as pulverized tablets (from several manufacturers), showed in all instances definite eczema reactions which exceeded the test areas and required local treatment with corticosteroids. Wang and Schmeo (1974) report the case of a patient with occupational allergy to isoniazid. Beside the allergic reaction of the immediate type (asthma bronchiale) there was a latent sensitization of the delayed reaction type (eczema reaction). This latent sensitization was manifested in a circumscribed area by the epicutaneous test. Reexposure to the allergen led to an asthmatic spasm of the bronchi and to recrudescence of the eczematous cutaneous efflorescences when it was inhaled. 

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