Isoniazid is a major antituberculosis drug.
5% of patients.
General: fever, flu-like syndrome.
Cutaneous: morbilliform, maculopapular or urticarial rash, contact dermatitis (occupational in nurses and manufactories).
Respiratory: lung infiltrates, interstitial pneumonia.
Intradermal skin-tests: 0.06 to 6 mg/ ml.
Patch-tests: isoniazid 2% in dis. water (contact dermatitis).
IgE-mediated hypersensitivity in a few cases.
Delayed hypersensitivity (contact dermatitis).
Desensitization is possible and effective. Start with 0.1 mg and go to 150 mg in 17 hours.