TB Skin Test (Mantoux Test)

  • The TB skin test, also known as the Mantoux test, tells if your body has been exposed to the TB germ.
  • The nurse will inject a small amount of fluid just under the skin of the left forearm.
  • You will see a little bubble or blister appear right away at the injection site.  This is normal and it will soon disappear.  
  • After 2-3 days, you will be asked to see the nurse to have the area checked and the reaction measured.
  • If there is no reaction after 2-3 days, you most probably have not been exposed to the TB germ.
  • If there is a reaction, some redness and a small bump will appear on the arm.  
  • A measurement of 10 millimetres or more is "positive", and means you may have the TB germ in your body.  At that point, the nurse will request additional information and tests, including chest x-ray and the collection of sputum samples.  When results are abnormal, the nurse will then consult with a medical health officer who may then recommend a further course of action.