Ethambutol allergic reactions

Optic neuritis (a decrease in visual acuity and changes in color perception), which appears to be related to the dose given and die duration of treatment, has occurred in some patients receiving ethambutol. Usually, tiiis adverse reaction disappears when the drug is discontinued. Other adverse reactions are dermatitis, pruritus, anaphylactoid reactions (unusual or exaggerated allergic reactions), joint pain, anorexia, nausea, and vomiting. 

The major toxicity associated with ethambutol use is retrobulbar neuritis impairing visual acuity and red-green color discrimination this side effect is dose related and reverses slowly once the drug is discontinued. Mild GI intolerance, allergic reaction, fever, dizziness, and mental confusion are also possible. Hyperuricemia is associated with ethambutol use due to a decreased renal excretion of urates gouty arthritis may result. 

Cutaneous allergic reactions to thiacetazone are very common in HIV-positive patients, in the order of 20%. Ethambutol should therefore be used instead of thiacetazone in these patients (10). 

Real allergic reactions after treatment with ethambutol are rare. 

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