In such cases withdraw and do not restart ATT till the rash has subsided completely. Once the rash has subsided, the offending drug has to be first identified.

If thaicetazone was used, it should not be used again. Other drugs should be reintroduced one by one  first in small doses.

The order of reintroduction of the drugs depends on the relative likelihood of the drugs to cause a skin reaction. The least likely drug is introduced first. The chart suggests a practical approach to identify the offending drug.

If the initial skin reaction was severe, start with approximately 1/10th of the dose shown for the first day. If no reaction occurs to this dose, the schedule for the 2nd and 3rd day should remain as shown above.

If possible, give two anti-TB drugs which the patient has not had before, while identifying the offending drug. This will prevent the emergence of drug resistance during the period in which the patient is being challenged. When restarting treatment, always consider it as a start of fresh treatment.

Options for alternate regimes

• In case pyrazinamide is the offending drug, switch the regime to either of the 9 month regimes.

• If ethambutol or streptomycin is the offending drug withdraw it and replace it by the other.

Rarely, a patient may develop a skin reaction to isoniazid or rifampicin. These drugs are both irreplaceable in short course chemotherapy. Hence desensitisation has to be done in such a patient. This is best left to the specialist and the patient should be referred to him.

without any deleterious effect to the patient. The eruption subsides on cessation of treatment.

Rule out other skin conditions like furunculosis, scabies and taeniasis before making a diagnosis of drug induced rash. These conditions are common in our country and may afflict the patient receiving ATT.