Application of a combined regimen of INH and Thioacetazone (TH) under conditions of District Tuberculosis Programme having become a distinct possibility, the study observed its applicability and toxicity. In all, 127 patients discovered during a mass Case-finding investigation were treated in their homes with 300 mgm of INH and 150 mgm of thioacetazone in a single tablet once a day. Close supervision of patients, laboratory or clinical examination to elicit toxic/side effects were not practicable. During their initial motivation, patients were asked to report back in the event of occurrence of unpleasant symptoms. At subsequent drug collection, indirect questioning for side effects was done. An active search for toxicity was also made by the home visiting staff when they visited patients' homes for defaulter retrieval.

In all, 23 patients complained of possible side effects of thioacetazone, of which 5 were major and 18 of minor nature. Among the 5 patients, two had exfoliative dermatitis and three had generalised petechial haemorrhages. All were males above the age of 40 years. All recovered with withdrawal of drugs and anti histamines. The minor side effects were giddiness and vomiting. None died of thioacetazone toxicity. It is concluded that TH regimen can be used for mass application on account of therapeutic efficacy and low price but consequences of side effects must be borne in mind while using this drug combination under district programme conditions.