Report a new active, reactivated or suspect TB case and order medication


NH may cause mild to severe hepatic dysfunction

Hepatitis is non-predictable but correlated with age:

  • < 20 years: rare
  • 20-34 years: ~ 0.2%
  • 35-49 years: 1.5%
  • > 50 years: 2.4%
  • Perform baseline liver function test prior to initiating INH
  • Monitor patients at each follow-up appointment for symptoms of hepatitis (e.g. fatigue, weakness, malaise, anorexia, nausea or vomiting, dark urine and/or yellowing of the skin); should symptoms occur, perform liver function test immediately
  • Perform monthly liver function test and symptom review for patients ≥ 35 years
  • Discontinue INH immediately if AST level exceeds 5 times the upper normal limit or if symptoms of hepatic damage occur; refer to TB specialist (in 10-20% of patients, AST levels will elevate 2-3 times during the first months of therapy; these levels typically will return to normal despite continuance of the drug)
  • Monitoring blood chemistry for children is not recommended unless the child has hepatic disease or is taking other potentially hepatotoxic drugs
  • Child (< 5 years)
  • Pregnant
  • Immunocompromised
  • Contact of drug-resistant TB
  • Abnormal chest x-ray
  • History of liver disease
  • History of alcohol/substance abuse/misuse
  1. Canadian Pharmacists Association. (2008). Compendium of Pharmaceuticals and Specialties, online version (e-CPS)
  2. Public Health Agency of Canada and Canadian Lung Association/Canadian Thoracic Society. (2007). Canadian Tuberculosis Standards. (6th ed.). Ottawa